More refactoring

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/LayoutParsingPipeline.java

@@ -10,6 +10,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.pdfbox.Loader;
@@ -26,6 +27,7 @@ import com.knecon.fforesight.service.layoutparser.internal.api.queue.LayoutParsi
 import com.knecon.fforesight.service.layoutparser.processor.model.AbstractPageBlock;
 import com.knecon.fforesight.service.layoutparser.processor.model.ClassificationDocument;
 import com.knecon.fforesight.service.layoutparser.processor.model.ClassificationPage;
+import com.knecon.fforesight.service.layoutparser.processor.model.ClassificationSection;
 import com.knecon.fforesight.service.layoutparser.processor.model.graph.nodes.Document;
 import com.knecon.fforesight.service.layoutparser.processor.model.image.ClassifiedImage;
 import com.knecon.fforesight.service.layoutparser.processor.model.table.CleanRulings;
@@ -47,6 +49,7 @@ import com.knecon.fforesight.service.layoutparser.processor.services.blockificat
 import com.knecon.fforesight.service.layoutparser.processor.services.classification.DocuMineClassificationService;
 import com.knecon.fforesight.service.layoutparser.processor.services.classification.RedactManagerClassificationService;
 import com.knecon.fforesight.service.layoutparser.processor.services.classification.TaasClassificationService;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.DocstrumSegmentationService;
 import com.knecon.fforesight.service.layoutparser.processor.services.factory.DocumentGraphFactory;
 import com.knecon.fforesight.service.layoutparser.processor.services.mapper.DocumentDataMapper;
 import com.knecon.fforesight.service.layoutparser.processor.services.mapper.TaasDocumentDataMapper;
@@ -86,6 +89,7 @@ public class LayoutParsingPipeline {
     RedactManagerBlockificationService redactManagerBlockificationService;
     LayoutGridService layoutGridService;
     ObservationRegistry observationRegistry;
+    DocstrumSegmentationService docstrumSegmentationService;
 
 
     public LayoutParsingFinishedEvent parseLayoutAndSaveFilesToStorage(LayoutParsingRequest layoutParsingRequest) throws IOException {
@@ -243,11 +247,37 @@ public class LayoutParsingPipeline {
             PDRectangle cropbox = pdPage.getCropBox();
             CleanRulings cleanRulings = rulingCleaningService.getCleanRulings(pdfTableCells.get(pageNumber), stripper.getRulings());
 
-            ClassificationPage classificationPage = switch (layoutParsingType) {
-                case REDACT_MANAGER -> redactManagerBlockificationService.blockify(stripper.getTextPositionSequences(), cleanRulings.getHorizontal(), cleanRulings.getVertical());
-                case TAAS -> taasBlockificationService.blockify(stripper.getTextPositionSequences(), cleanRulings.getHorizontal(), cleanRulings.getVertical());
-                case DOCUMINE -> docuMineBlockificationService.blockify(stripper.getTextPositionSequences(), cleanRulings.getHorizontal(), cleanRulings.getVertical());
-            };
+            // Docstrum
+            AtomicInteger num = new AtomicInteger(pageNumber);
+            var zones = docstrumSegmentationService.segmentPage(stripper.getTextPositionSequences());
+
+            List<AbstractPageBlock> pageBlocks = new ArrayList<>();
+            AtomicInteger numOnPage = new AtomicInteger(1);
+//            List<TextPositionSequence> textPositionSequences = new ArrayList<>();
+            zones.forEach(zone -> {
+
+                List<TextPositionSequence> textPositionSequences = new ArrayList<>();
+                zone.getLines().forEach(line -> {
+                    line.getWords().forEach(word -> {
+                        textPositionSequences.add(new TextPositionSequence(word.getTextPositions(), num.get()));
+                    });
+                });
+
+                var cps = redactManagerBlockificationService.blockify(textPositionSequences, cleanRulings.getHorizontal(), cleanRulings.getVertical());
+
+                cps.getTextBlocks().forEach(cp -> {
+                    pageBlocks.add(redactManagerBlockificationService.buildTextBlock(((TextPageBlock) cp).getSequences(), numOnPage.getAndIncrement()));
+                });
+            });
+
+//            ClassificationPage classificationPage = switch (layoutParsingType) {
+//                case REDACT_MANAGER -> redactManagerBlockificationService.blockify(textPositionSequences, cleanRulings.getHorizontal(), cleanRulings.getVertical());
+//                case TAAS -> taasBlockificationService.blockify(textPositionSequences, cleanRulings.getHorizontal(), cleanRulings.getVertical());
+//                case DOCUMINE -> docuMineBlockificationService.blockify(textPositionSequences, cleanRulings.getHorizontal(), cleanRulings.getVertical());
+//            };
+
+            ClassificationPage classificationPage = new ClassificationPage(pageBlocks);
+
             classificationPage.setCleanRulings(cleanRulings);
             classificationPage.setRotation(rotation);
             classificationPage.setLandscape(isLandscape);
@@ -283,9 +313,19 @@ public class LayoutParsingPipeline {
             case REDACT_MANAGER -> redactManagerClassificationService.classifyDocument(classificationDocument);
         }
 
+        List<ClassificationSection> sections = new ArrayList<>();
+        for (var page : classificationPages) {
+            page.getTextBlocks().forEach(block -> {
+                block.setPage(page.getPageNumber());
+                var section = sectionsBuilderService.buildTextBlock(List.of(block), "a");
+                sections.add(section);
+            });
+        }
+        classificationDocument.setSections(sections);
+
         log.info("Building Sections for {}", identifier);
-        sectionsBuilderService.buildSections(classificationDocument);
-        sectionsBuilderService.addImagesToSections(classificationDocument);
+//        sectionsBuilderService.buildSections(classificationDocument);
+//        sectionsBuilderService.addImagesToSections(classificationDocument);
         return classificationDocument;
     }
 

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/model/ClassificationPage.java

@@ -12,15 +12,16 @@ import com.knecon.fforesight.service.layoutparser.processor.model.table.CleanRul
 import com.knecon.fforesight.service.layoutparser.processor.model.text.StringFrequencyCounter;
 
 import lombok.Data;
+import lombok.Getter;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
-import org.apache.pdfbox.pdmodel.documentinterchange.markedcontent.PDMarkedContent;
 
 @Data
 @RequiredArgsConstructor
 public class ClassificationPage {
 
     @NonNull
+    @Getter
     private List<AbstractPageBlock> textBlocks;
 
     private List<ClassifiedImage> images = new ArrayList<>();

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/model/text/RedTextPosition.java

@@ -45,6 +45,9 @@ public class RedTextPosition {
     @JsonIgnore
     private String fontName;
 
+    @JsonIgnore
+    private RedTextPosition parent;
+
 
     @SneakyThrows
     public static RedTextPosition fromTextPosition(TextPosition textPosition) {

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/model/text/TextPageBlock.java

@@ -17,6 +17,7 @@ import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
+import lombok.Getter;
 import lombok.NoArgsConstructor;
 
 @EqualsAndHashCode(callSuper = true)
@@ -27,6 +28,7 @@ import lombok.NoArgsConstructor;
 public class TextPageBlock extends AbstractPageBlock {
 
     @Builder.Default
+    @Getter
     private List<TextPositionSequence> sequences = new ArrayList<>();
 
     @JsonIgnore
@@ -73,7 +75,7 @@ public class TextPageBlock extends AbstractPageBlock {
 
         return sequences.get(0).getPageWidth();
     }
-    
+
 
     public static TextPageBlock merge(List<TextPageBlock> textBlocksToMerge) {
 
@@ -82,6 +84,7 @@ public class TextPageBlock extends AbstractPageBlock {
         return fromTextPositionSequences(sequences);
     }
 
+
     public static TextPageBlock fromTextPositionSequences(List<TextPositionSequence> wordBlockList) {
 
         TextPageBlock textBlock = null;
@@ -133,7 +136,6 @@ public class TextPageBlock extends AbstractPageBlock {
     }
 
 
-
     /**
      * Returns the minX value in pdf coordinate system.
      * Note: This needs to use Pdf Coordinate System where {0,0} rotated with the page rotation.

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/model/text/TextPositionSequence.java

@@ -55,6 +55,18 @@ public class TextPositionSequence implements CharSequence {
     }
 
 
+    public TextPositionSequence(List<RedTextPosition> textPositions, int page) {
+
+        this.textPositions = textPositions;
+        this.page = page;
+        this.dir = TextDirection.fromDegrees(textPositions.get(0).getDir());
+        this.rotation = textPositions.get(0).getRotation();
+        this.pageHeight = textPositions.get(0).getPageHeight();
+        this.pageWidth = textPositions.get(0).getPageWidth();
+        this.isParagraphStart = false;
+    }
+
+
     @Override
     public int length() {
 

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/SectionsBuilderService.java

@@ -240,7 +240,7 @@ public class SectionsBuilderService {
     }
 
 
-    private ClassificationSection buildTextBlock(List<AbstractPageBlock> wordBlockList, String lastHeadline) {
+    public ClassificationSection buildTextBlock(List<AbstractPageBlock> wordBlockList, String lastHeadline) {
 
         ClassificationSection section = new ClassificationSection();
 

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/blockification/RedactManagerBlockificationService.java

@@ -57,7 +57,7 @@ public class RedactManagerBlockificationService {
             boolean isSplitByRuling = isSplitByRuling(minX, minY, maxX, maxY, word, horizontalRulingLines, verticalRulingLines);
             boolean splitByDir = prev != null && !prev.getDir().equals(word.getDir());
 
-            if (prev != null && (lineSeparation || startFromTop || splitByX || splitByDir || isSplitByRuling)) {
+            if (prev != null && (splitByDir || isSplitByRuling)) {
 
                 Orientation prevOrientation = null;
                 if (!chunkBlockList.isEmpty()) {
@@ -167,7 +167,7 @@ public class RedactManagerBlockificationService {
     }
 
 
-    private TextPageBlock buildTextBlock(List<TextPositionSequence> wordBlockList, int indexOnPage) {
+    public TextPageBlock buildTextBlock(List<TextPositionSequence> wordBlockList, int indexOnPage) {
 
         TextPageBlock textBlock = null;
 

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/DocstrumSegmentationService.java

@@ -0,0 +1,153 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.model.text.TextPositionSequence;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Character;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.DisjointSets;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Line;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Zone;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service.LineBuilderService;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service.NearestNeighbourService;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service.ReadingOrderService;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service.SpacingService;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service.ZoneBuilderService;
+
+import lombok.RequiredArgsConstructor;
+
+@Service
+@RequiredArgsConstructor
+public class DocstrumSegmentationService {
+
+    private static final double MAX_VERTICAL_MERGE_DIST = 0.5;
+
+    private final NearestNeighbourService nearestNeighbourService;
+    private final SpacingService spacingService;
+    private final LineBuilderService lineBuilderService;
+    private final ZoneBuilderService zoneBuilderService;
+    private final ReadingOrderService readingOrderService;
+
+
+    public List<Zone> segmentPage(List<TextPositionSequence> textPositions) {
+
+        var positions = textPositions.stream().map(TextPositionSequence::getTextPositions).flatMap(List::stream).toList();
+
+        var characters = positions.stream().map(Character::new).collect(Collectors.toList());
+
+        nearestNeighbourService.findNearestNeighbors(characters);
+
+        var characterSpacing = spacingService.computeCharacterSpacing(characters);
+        var lineSpacing = spacingService.computeLineSpacing(characters);
+
+        var lines = lineBuilderService.buildLines(characters, characterSpacing, lineSpacing);
+
+        var zones = zoneBuilderService.buildZones(lines, characterSpacing, lineSpacing);
+
+        zones = mergeLinesInZones(zones, characterSpacing, Double.NEGATIVE_INFINITY, 0.0, 0.0, lineSpacing * MAX_VERTICAL_MERGE_DIST);
+
+        return readingOrderService.resolve(zones, false);
+    }
+
+//    private List<Zone> mergeZones(List<Zone> zones, double tolerance) {
+//
+//        List<BxBounds> bounds = new ArrayList<BxBounds>(zones.size());
+//        for (List<ComponentLine> zone : zones) {
+//            BxBoundsBuilder builder = new BxBoundsBuilder();
+//            for (ComponentLine line : zone) {
+//                for (Component component : line.getComponents()) {
+//                    builder.expand(component.getChunk().getBounds());
+//                }
+//            }
+//            bounds.add(builder.getBounds());
+//        }
+//
+//        List<List<ComponentLine>> outputZones = new ArrayList<List<ComponentLine>>();
+//        mainFor:
+//        for (int i = 0; i < zones.size(); i++) {
+//            for (int j = 0; j < zones.size(); j++) {
+//                if (i == j || bounds.get(j) == null || bounds.get(i) == null) {
+//                    continue;
+//                }
+//                if (BxModelUtils.contains(bounds.get(j), bounds.get(i), tolerance)) {
+//                    zones.get(j).addAll(zones.get(i));
+//                    bounds.set(i, null);
+//                    continue mainFor;
+//                }
+//            }
+//            outputZones.add(zones.get(i));
+//        }
+//        return outputZones;
+//    }
+
+
+    private List<Zone> mergeLinesInZones(List<Zone> zones,
+                                         double wordSpacing,
+                                         double minHorizontalDistance,
+                                         double maxHorizontalDistance,
+                                         double minVerticalDistance,
+                                         double maxVerticalDistance) {
+
+        List<Zone> outputZones = new ArrayList<>(zones.size());
+        for (Zone zone : zones) {
+            outputZones.add(mergeLinesInZone(zone, wordSpacing, minHorizontalDistance, maxHorizontalDistance, minVerticalDistance, maxVerticalDistance));
+        }
+        return outputZones;
+    }
+
+
+    private Zone mergeLinesInZone(Zone zone,
+                                  double wordSpacing,
+                                  double minHorizontalDistance,
+                                  double maxHorizontalDistance,
+                                  double minVerticalDistance,
+                                  double maxVerticalDistance) {
+
+        DisjointSets<Line> sets = new DisjointSets<>(zone.getLines());
+        for (int i = 0; i < zone.getLines().size(); i++) {
+            Line li = zone.getLines().get(i);
+            for (int j = i + 1; j < zone.getLines().size(); j++) {
+                Line lj = zone.getLines().get(j);
+                double hDist = li.horizontalDistance(lj);
+                double vDist = li.verticalDistance(lj);
+                if (minHorizontalDistance <= hDist && hDist <= maxHorizontalDistance && minVerticalDistance <= vDist && vDist <= maxVerticalDistance) {
+                    sets.union(li, lj);
+                } else if (minVerticalDistance <= vDist && vDist <= maxVerticalDistance && Math.abs(hDist - Math.min(li.getLength(), lj.getLength())) < 0.1) {
+                    boolean componentOverlap = false;
+                    int overlappingCount = 0;
+                    for (Character ci : li.getCharacters()) {
+                        for (Character cj : lj.getCharacters()) {
+                            double dist = ci.overlappingDistance(cj);
+                            if (dist > 2) {
+                                componentOverlap = true;
+                            }
+                            if (dist > 0) {
+                                overlappingCount++;
+                            }
+                        }
+                    }
+                    if (!componentOverlap && overlappingCount <= 2) {
+                        sets.union(li, lj);
+                    }
+                }
+            }
+        }
+        List<Line> outputZone = new ArrayList<>();
+        for (Set<Line> group : sets) {
+            List<Character> components = new ArrayList<>();
+            for (Line line : group) {
+                components.addAll(line.getCharacters());
+            }
+            components.sort(Comparator.comparingDouble(Character::getX));
+
+            outputZone.add(new Line(components, wordSpacing));
+        }
+        return new Zone(outputZone);
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/AngleFilter.java

@@ -0,0 +1,32 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+public class AngleFilter {
+
+    protected double lowerAngle;
+    protected double upperAngle;
+
+
+    public AngleFilter(double lowerAngle, double upperAngle) {
+
+        if (lowerAngle < -Math.PI / 2) {
+            lowerAngle += Math.PI;
+        }
+        if (upperAngle >= Math.PI / 2) {
+            upperAngle -= Math.PI;
+        }
+
+        this.lowerAngle = lowerAngle;
+        this.upperAngle = upperAngle;
+    }
+
+
+    public boolean matches(Neighbor neighbor) {
+
+        if (lowerAngle <= upperAngle) {
+            return lowerAngle <= neighbor.getAngle() && neighbor.getAngle() < upperAngle;
+        } else {
+            return lowerAngle <= neighbor.getAngle() || neighbor.getAngle() < upperAngle;
+        }
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/BoundingBox.java

@@ -0,0 +1,48 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import java.awt.geom.Rectangle2D;
+
+import lombok.Data;
+
+@Data
+public abstract class BoundingBox {
+
+    private Rectangle2D bBox;
+
+
+    public double getX() {
+
+        return bBox.getX();
+    }
+
+
+    public double getY() {
+
+        return bBox.getY();
+    }
+
+
+    public double getWidth() {
+
+        return bBox.getWidth();
+    }
+
+
+    public double getHeight() {
+
+        return bBox.getHeight();
+    }
+
+
+    public double getArea() {
+
+        return (bBox.getHeight() * bBox.getWidth());
+    }
+
+
+    public boolean contains(Rectangle2D contained, double tolerance) {
+
+        return bBox.getX() <= contained.getX() + tolerance && bBox.getY() <= contained.getY() + tolerance && bBox.getX() + bBox.getWidth() >= contained.getX() + contained.getWidth() - tolerance && bBox.getY() + bBox.getHeight() >= contained.getY() + contained.getHeight() - tolerance;
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/Character.java

@@ -0,0 +1,84 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import com.knecon.fforesight.service.layoutparser.processor.model.text.RedTextPosition;
+
+import lombok.Data;
+
+@Data
+public class Character {
+
+    private final double x;
+    private final double y;
+    private final RedTextPosition textPosition;
+
+    private List<Neighbor> neighbors = new ArrayList<>();
+
+
+    public Character(RedTextPosition chunk) {
+
+        this.x = chunk.getXDirAdj() + chunk.getWidthDirAdj() / 2;
+        this.y = chunk.getYDirAdj() + chunk.getHeightDir() / 2;
+        this.textPosition = chunk;
+    }
+
+
+    public double getHeight() {
+
+        return textPosition.getHeightDir();
+    }
+
+
+    public double distance(Character character) {
+
+        double dx = getX() - character.getX();
+        double dy = getY() - character.getY();
+        return Math.sqrt(dx * dx + dy * dy);
+    }
+
+
+    public double horizontalDistance(Character character) {
+
+        return Math.abs(getX() - character.getX());
+    }
+
+
+    public double verticalDistance(Character character) {
+
+        return Math.abs(getY() - character.getY());
+    }
+
+
+    public double overlappingDistance(Character other) {
+
+        double[] xs = new double[4];
+        double s = Math.sin(-0), c = Math.cos(-0);
+        xs[0] = c * x - s * y;
+        xs[1] = c * (x + textPosition.getWidthDirAdj()) - s * (y + textPosition.getHeightDir());
+        xs[2] = c * other.x - s * other.y;
+        xs[3] = c * (other.x + other.textPosition.getWidthDirAdj()) - s * (other.y + other.textPosition.getHeightDir());
+        boolean overlapping = xs[1] >= xs[2] && xs[3] >= xs[0];
+        Arrays.sort(xs);
+        return Math.abs(xs[2] - xs[1]) * (overlapping ? 1 : -1);
+    }
+
+
+    public void setNeighbors(List<Neighbor> neighbors) {
+
+        this.neighbors = neighbors;
+    }
+
+
+    public double angle(Character character) {
+
+        if (getX() > character.getX()) {
+            return Math.atan2(getY() - character.getY(), getX() - character.getX());
+        } else {
+            return Math.atan2(character.getY() - getY(), character.getX() - getX());
+        }
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/DisjointSets.java

@@ -0,0 +1,194 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import java.util.AbstractSet;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
+public class DisjointSets<E> implements Iterable<Set<E>> {
+
+    private final Map<E, Entry<E>> map = new HashMap<>();
+
+
+    public DisjointSets(Collection<? extends E> collection) {
+
+        for (E element : collection) {
+            map.put(element, new Entry<E>(element));
+        }
+    }
+
+
+    public boolean areTogether(E e1, E e2) {
+
+        return map.get(e1).findRepresentative() == map.get(e2).findRepresentative();
+    }
+
+
+    public void union(E e1, E e2) {
+
+        Entry<E> r1 = map.get(e1).findRepresentative();
+        Entry<E> r2 = map.get(e2).findRepresentative();
+        if (r1 != r2) {
+            if (r1.size <= r2.size) {
+                r2.mergeWith(r1);
+            } else {
+                r1.mergeWith(r2);
+            }
+        }
+    }
+
+
+    @Override
+    public Iterator<Set<E>> iterator() {
+
+        return new Iterator<>() {
+
+            private final Iterator<Entry<E>> iterator = map.values().iterator();
+            private Entry<E> nextRepresentative;
+
+            {
+                findNextRepresentative();
+            }
+
+            @Override
+            public boolean hasNext() {
+
+                return nextRepresentative != null;
+            }
+
+
+            @Override
+            public Set<E> next() {
+
+                if (nextRepresentative == null) {
+                    throw new NoSuchElementException();
+                }
+                Set<E> result = nextRepresentative.asSet();
+                findNextRepresentative();
+                return result;
+            }
+
+
+            private void findNextRepresentative() {
+
+                while (iterator.hasNext()) {
+                    Entry<E> candidate = iterator.next();
+                    if (candidate.isRepresentative()) {
+                        nextRepresentative = candidate;
+                        return;
+                    }
+                }
+                nextRepresentative = null;
+            }
+
+
+            @Override
+            public void remove() {
+
+                throw new UnsupportedOperationException();
+            }
+
+        };
+    }
+
+
+    private static class Entry<E> {
+
+        private int size = 1;
+        private final E value;
+        private Entry<E> parent = this;
+        private Entry<E> next = null;
+        private Entry<E> last = this;
+
+
+        Entry(E value) {
+
+            this.value = value;
+        }
+
+
+        void mergeWith(Entry<E> otherRepresentative) {
+
+            size += otherRepresentative.size;
+            last.next = otherRepresentative;
+            last = otherRepresentative.last;
+            otherRepresentative.parent = this;
+        }
+
+
+        Entry<E> findRepresentative() {
+
+            Entry<E> representative = parent;
+            while (representative.parent != representative) {
+                representative = representative.parent;
+            }
+            for (Entry<E> entry = this; entry != representative; ) {
+                Entry<E> nextEntry = entry.parent;
+                entry.parent = representative;
+                entry = nextEntry;
+            }
+            return representative;
+        }
+
+
+        boolean isRepresentative() {
+
+            return parent == this;
+        }
+
+
+        Set<E> asSet() {
+
+            return new AbstractSet<E>() {
+
+                @Override
+                public Iterator<E> iterator() {
+
+                    return new Iterator<E>() {
+
+                        private Entry<E> nextEntry = findRepresentative();
+
+
+                        @Override
+                        public boolean hasNext() {
+
+                            return nextEntry != null;
+                        }
+
+
+                        @Override
+                        public E next() {
+
+                            if (nextEntry == null) {
+                                throw new NoSuchElementException();
+                            }
+                            E result = nextEntry.value;
+                            nextEntry = nextEntry.next;
+                            return result;
+                        }
+
+
+                        @Override
+                        public void remove() {
+
+                            throw new UnsupportedOperationException();
+                        }
+
+                    };
+                }
+
+
+                @Override
+                public int size() {
+
+                    return findRepresentative().size;
+                }
+            };
+        }
+
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/Histogram.java

@@ -0,0 +1,91 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+public class Histogram {
+
+    private static final double EPSILON = 1.0e-6;
+    private final double min;
+    private final double resolution;
+    private double[] frequencies;
+
+
+    public Histogram(double minValue, double maxValue, double resolution) {
+
+        this.min = minValue - EPSILON;
+        double delta = maxValue - minValue + 2 * EPSILON;
+        int size = Math.max(1, (int) Math.round((maxValue - minValue) / resolution));
+        this.resolution = delta / size;
+        this.frequencies = new double[size];
+    }
+
+
+    public void kernelSmooth(double[] kernel) {
+
+        double[] newFrequencies = new double[frequencies.length];
+        int shift = (kernel.length - 1) / 2;
+        for (int i = 0; i < kernel.length; i++) {
+            int jStart = Math.max(0, i - shift);
+            int jEnd = Math.min(frequencies.length, frequencies.length + i - shift);
+            for (int j = jStart; j < jEnd; j++) {
+                newFrequencies[j - i + shift] += kernel[i] * frequencies[j];
+            }
+        }
+        frequencies = newFrequencies;
+    }
+
+
+    public double[] createGaussianKernel(double length, double stdDeviation) {
+
+        int r = (int) Math.round(length / resolution) / 2;
+        stdDeviation /= resolution;
+
+        int size = 2 * r + 1;
+        double[] kernel = new double[size];
+        double sum = 0;
+        double b = 2 * stdDeviation * stdDeviation;
+        double a = 1 / Math.sqrt(Math.PI * b);
+        for (int i = 0; i < size; i++) {
+            kernel[i] = a * Math.exp(-(i - r) * (i - r) / b);
+            sum += kernel[i];
+        }
+        for (int i = 0; i < size; i++) {
+            kernel[i] /= sum;
+        }
+        return kernel;
+    }
+
+
+    public void gaussianSmooth(double windowLength, double stdDeviation) {
+
+        kernelSmooth(createGaussianKernel(windowLength, stdDeviation));
+    }
+
+
+    public void add(double value) {
+
+        frequencies[(int) ((value - min) / resolution)] += 1.0;
+    }
+
+
+    public int getSize() {
+
+        return frequencies.length;
+    }
+
+
+    public double getPeakValue() {
+
+        int peakIndex = 0;
+        for (int i = 1; i < frequencies.length; i++) {
+            if (frequencies[i] > frequencies[peakIndex]) {
+                peakIndex = i;
+            }
+        }
+        int peakEndIndex = peakIndex + 1;
+        final double EPS = 0.0001;
+        while (peakEndIndex < frequencies.length && Math.abs(frequencies[peakEndIndex] - frequencies[peakIndex]) < EPS) {
+            peakEndIndex++;
+        }
+        return ((double) peakIndex + peakEndIndex) / 2 * resolution + min;
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/Line.java

@@ -0,0 +1,165 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import java.awt.geom.Rectangle2D;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import com.knecon.fforesight.service.layoutparser.processor.model.text.TextPositionSequence;
+
+import lombok.Data;
+
+@Data
+public class Line extends BoundingBox {
+
+    private static final double WORD_DISTANCE_MULTIPLIER = 0.2;
+
+    private final double x0;
+    private final double y0;
+
+    private final double x1;
+    private final double y1;
+
+    private final double height;
+
+    private final List<Character> characters;
+    private final List<TextPositionSequence> words = new ArrayList<>();
+
+
+    public Line(List<Character> characters, double wordSpacing) {
+
+        this.characters = characters;
+
+        if (characters.size() >= 2) {
+            // linear regression
+            double sx = 0.0, sxx = 0.0, sxy = 0.0, sy = 0.0;
+            for (Character character : characters) {
+                sx += character.getX();
+                sxx += character.getX() * character.getX();
+                sxy += character.getX() * character.getY();
+                sy += character.getY();
+            }
+            double b = (characters.size() * sxy - sx * sy) / (characters.size() * sxx - sx * sx);
+            double a = (sy - b * sx) / characters.size();
+
+            this.x0 = characters.get(0).getX();
+            this.y0 = a + b * this.x0;
+            this.x1 = characters.get(characters.size() - 1).getX();
+            this.y1 = a + b * this.x1;
+        } else {
+            Character character = characters.get(0);
+            double dx = character.getTextPosition().getWidthDirAdj() / 3;
+            double dy = dx * Math.tan(0);
+            this.x0 = character.getX() - dx;
+            this.x1 = character.getX() + dx;
+            this.y0 = character.getY() - dy;
+            this.y1 = character.getY() + dy;
+        }
+        height = computeHeight();
+        computeWords(wordSpacing * WORD_DISTANCE_MULTIPLIER);
+        buildBBox();
+    }
+
+
+    public double getAngle() {
+
+        return Math.atan2(y1 - y0, x1 - x0);
+    }
+
+
+    public double getLength() {
+
+        return Math.sqrt((x0 - x1) * (x0 - x1) + (y0 - y1) * (y0 - y1));
+    }
+
+
+    private double computeHeight() {
+
+        double sum = 0.0;
+        for (Character component : characters) {
+            sum += component.getHeight();
+        }
+        return sum / characters.size();
+    }
+
+
+    public double angularDifference(Line j) {
+
+        double diff = Math.abs(getAngle() - j.getAngle());
+        if (diff <= Math.PI / 2) {
+            return diff;
+        } else {
+            return Math.PI - diff;
+        }
+    }
+
+
+    public double horizontalDistance(Line other) {
+
+        double[] xs = new double[4];
+        xs[0] = x0;
+        xs[1] = x1;
+        xs[2] = other.x0;
+        xs[3] = other.x1;
+        boolean overlapping = xs[1] >= xs[2] && xs[3] >= xs[0];
+        Arrays.sort(xs);
+        return Math.abs(xs[2] - xs[1]) * (overlapping ? 1 : -1);
+    }
+
+
+    public double verticalDistance(Line other) {
+
+        double ym = (y0 + y1) / 2;
+        double yn = (other.y0 + other.y1) / 2;
+        return Math.abs(ym - yn) / Math.sqrt(1);
+    }
+
+
+    private void computeWords(double wordSpacing) {
+
+        TextPositionSequence word = new TextPositionSequence();
+        Character previous = null;
+        for (Character current : characters) {
+            if (previous != null) {
+                double dist = current.getTextPosition().getXDirAdj() - previous.getTextPosition().getXDirAdj() - previous.getTextPosition().getWidthDirAdj();
+                if (dist > wordSpacing) {
+                    words.add(word);
+                    word = new TextPositionSequence();
+                }
+            }
+            word.getTextPositions().add(current.getTextPosition());
+            previous = current;
+        }
+        words.add(word);
+    }
+
+
+    private void buildBBox() {
+
+        double minX = Double.POSITIVE_INFINITY;
+        double minY = Double.POSITIVE_INFINITY;
+        double maxX = Double.NEGATIVE_INFINITY;
+        double maxY = Double.NEGATIVE_INFINITY;
+
+        for (Character character : characters) {
+
+            minX = Math.min(minX, character.getTextPosition().getXDirAdj());
+            minY = Math.min(minY, character.getTextPosition().getYDirAdj());
+            maxX = Math.max(maxX, character.getTextPosition().getXDirAdj() + character.getTextPosition().getWidthDirAdj());
+            maxY = Math.max(maxY, character.getTextPosition().getYDirAdj() + character.getTextPosition().getHeightDir());
+
+        }
+
+        this.setBBox(new Rectangle2D.Double(minX, minY, maxX - minX, maxY - minY));
+    }
+
+
+    public String toString() {
+
+        StringBuilder sb = new StringBuilder();
+        words.forEach(word -> sb.append(word.toString()).append(" "));
+        return sb.toString().trim();
+    }
+
+}
+

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/Neighbor.java

@@ -0,0 +1,36 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import lombok.Getter;
+
+public class Neighbor {
+
+    @Getter
+    private final double distance;
+    @Getter
+    private final double angle;
+    private final Character originCharacter;
+    @Getter
+    private final Character character;
+
+
+    public Neighbor(Character neighbor, Character origin) {
+
+        this.distance = neighbor.distance(origin);
+        this.angle = neighbor.angle(origin);
+        this.character = neighbor;
+        this.originCharacter = origin;
+    }
+
+
+    public double getHorizontalDistance() {
+
+        return character.horizontalDistance(originCharacter);
+    }
+
+
+    public double getVerticalDistance() {
+
+        return character.verticalDistance(originCharacter);
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/model/Zone.java

@@ -0,0 +1,50 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model;
+
+import java.awt.geom.Rectangle2D;
+import java.util.Comparator;
+import java.util.List;
+
+import lombok.Data;
+
+@Data
+public class Zone extends BoundingBox {
+
+    private List<Line> lines;
+
+
+    public Zone(List<Line> lines) {
+
+        lines.sort(Comparator.comparingDouble(Line::getY));
+        this.lines = lines;
+        buildBBox();
+    }
+
+
+    public void buildBBox() {
+
+        double minX = Double.POSITIVE_INFINITY;
+        double minY = Double.POSITIVE_INFINITY;
+        double maxX = Double.NEGATIVE_INFINITY;
+        double maxY = Double.NEGATIVE_INFINITY;
+
+        for (Line line : lines) {
+
+            minX = Math.min(minX, line.getX());
+            minY = Math.min(minY, line.getY());
+            maxX = Math.max(maxX, line.getX() + line.getWidth());
+            maxY = Math.max(maxY, line.getY() + line.getHeight());
+
+        }
+
+        this.setBBox(new Rectangle2D.Double(minX, minY, maxX - minX, maxY - minY));
+    }
+
+
+    public String toString() {
+
+        StringBuilder sb = new StringBuilder();
+        lines.forEach(line -> sb.append(line.toString()).append("\n"));
+        return sb.toString().trim();
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/service/LineBuilderService.java

@@ -0,0 +1,50 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.AngleFilter;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Character;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.DisjointSets;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Line;
+
+@Service
+public class LineBuilderService {
+
+    private static final double CHARACTER_SPACING_DISTANCE_MULTIPLIER = 3.5;
+    private static final double MAX_VERTICAL_CHARACTER_DISTANCE = 0.67;
+    private static final double ANGLE_TOLERANCE = Math.PI / 6;
+
+
+    public List<Line> buildLines(List<Character> characters, double characterSpacing, double lineSpacing) {
+
+        double maxHorizontalDistance = characterSpacing * CHARACTER_SPACING_DISTANCE_MULTIPLIER;
+        double maxVerticalDistance = lineSpacing * MAX_VERTICAL_CHARACTER_DISTANCE;
+
+        DisjointSets<Character> sets = new DisjointSets<>(characters);
+        AngleFilter filter = new AngleFilter(-ANGLE_TOLERANCE, ANGLE_TOLERANCE);
+
+        characters.forEach(character -> {
+            character.getNeighbors().forEach(neighbor -> {
+                double x = neighbor.getHorizontalDistance() / maxHorizontalDistance;
+                double y = neighbor.getVerticalDistance() / maxVerticalDistance;
+                if (filter.matches(neighbor) && Math.pow(x, 2) + Math.pow(y, 2) <= 1) {
+                    sets.union(character, neighbor.getCharacter());
+                }
+            });
+        });
+
+        List<Line> lines = new ArrayList<>();
+        sets.forEach(group -> {
+            List<Character> lineComponents = new ArrayList<>(group);
+            lineComponents.sort(Comparator.comparingDouble(Character::getX));
+            lines.add(new Line(lineComponents, characterSpacing));
+        });
+
+        return lines;
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/service/NearestNeighbourService.java

@@ -0,0 +1,78 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Character;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Neighbor;
+
+@Service
+public class NearestNeighbourService {
+
+    private static final int NUMBER_OF_NEIGHBOURS = 8;
+    private static final double STEP = 16.0;
+
+
+    public void findNearestNeighbors(List<Character> characters) {
+
+        if (characters.isEmpty()) {
+            return;
+        }
+
+        characters.sort(Comparator.comparingDouble(Character::getX));
+
+        int maxNeighborCount = NUMBER_OF_NEIGHBOURS;
+        if (characters.size() <= NUMBER_OF_NEIGHBOURS) {
+            maxNeighborCount = characters.size() - 1;
+        }
+
+        for (int i = 0; i < characters.size(); i++) {
+
+            List<Neighbor> candidates = new ArrayList<>();
+
+            int start = i;
+            int end = i + 1;
+
+            double distance = Double.POSITIVE_INFINITY;
+
+            for (double searchDistance = 0; searchDistance < distance; ) {
+
+                searchDistance += STEP;
+                boolean newCandidatesFound = false;
+
+                while (start > 0 && characters.get(i).getX() - characters.get(start - 1).getX() < searchDistance) {
+                    start--;
+                    candidates.add(new Neighbor(characters.get(start), characters.get(i)));
+                    clearLeastDistant(candidates, maxNeighborCount);
+                    newCandidatesFound = true;
+                }
+
+                while (end < characters.size() && characters.get(end).getX() - characters.get(i).getX() < searchDistance) {
+                    candidates.add(new Neighbor(characters.get(end), characters.get(i)));
+                    clearLeastDistant(candidates, maxNeighborCount);
+                    end++;
+                    newCandidatesFound = true;
+                }
+
+                if (newCandidatesFound && candidates.size() >= maxNeighborCount) {
+                    distance = candidates.get(maxNeighborCount - 1).getDistance();
+                }
+            }
+            clearLeastDistant(candidates, maxNeighborCount);
+            characters.get(i).setNeighbors(new ArrayList<>(candidates));
+        }
+    }
+
+
+    private void clearLeastDistant(List<Neighbor> candidates, int maxNeighborCount) {
+
+        if (candidates.size() > maxNeighborCount) {
+            candidates.sort(Comparator.comparingDouble(Neighbor::getDistance));
+            candidates.remove(candidates.remove(candidates.size() - 1));
+        }
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/service/ReadingOrderService.java

@@ -0,0 +1,99 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.BoundingBox;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Zone;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.utils.DoubleUtils;
+
+@Service
+public class ReadingOrderService {
+
+    private static final double THRESHOLD = 1;
+
+
+    public List<Zone> resolve(List<Zone> zones, boolean yxOrder) {
+
+        if (zones.isEmpty() || zones.size() == 1) {
+            return zones;
+        }
+
+        if (yxOrder) {
+            zones.sort(Comparator.comparing(BoundingBox::getY, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD))
+                    .thenComparing(BoundingBox::getX, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD)));
+            return zones;
+        }
+
+        return resolveMultiColumnReadingOder(zones);
+    }
+
+
+    private List<Zone> resolveMultiColumnReadingOder(List<Zone> zones) {
+
+        // Simple reading order resolver for multi column page layout as described here : https://pub.towardsai.net/advanced-rag-02-unveiling-pdf-parsing-b84ae866344e
+        // TODO implement a more fancy reading order resolver see https://github.com/BobLd/DocumentLayoutAnalysis/blob/master/README.md#reading-order
+
+        double minX = Double.POSITIVE_INFINITY;
+        double maxX = Double.NEGATIVE_INFINITY;
+
+        for (Zone zone : zones) {
+            if (zone.getX() < minX) {
+                minX = zone.getX();
+            }
+            if (zone.getX() + zone.getWidth() > maxX) {
+                maxX = zone.getX() + zone.getWidth();
+            }
+        }
+
+        double midLineXCoordinate = (minX + maxX) / 2;
+
+        List<Zone> leftOf = new ArrayList<>();
+        List<Zone> rightOf = new ArrayList<>();
+        List<Zone> middle = new ArrayList<>();
+        for (Zone zone : zones) {
+            if (zone.getX() < midLineXCoordinate && zone.getX() + zone.getWidth() < midLineXCoordinate) {
+                leftOf.add(zone);
+            } else if (zone.getX() > midLineXCoordinate && zone.getX() + zone.getWidth() > midLineXCoordinate) {
+                rightOf.add(zone);
+            } else {
+                middle.add(zone);
+            }
+        }
+
+        leftOf.sort(Comparator.comparing(BoundingBox::getY, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD))
+                .thenComparing(BoundingBox::getX, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD)));
+
+        rightOf.sort(Comparator.comparing(BoundingBox::getY, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD))
+                .thenComparing(BoundingBox::getX, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD)));
+
+        middle.sort(Comparator.comparing(BoundingBox::getY, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD))
+                .thenComparing(BoundingBox::getX, (o1, o2) -> DoubleUtils.compareDouble(o1, o2, THRESHOLD)));
+
+        List<Zone> sortedZones = new ArrayList<>();
+        sortedZones.addAll(leftOf);
+        sortedZones.addAll(rightOf);
+
+        ListIterator<Zone> itty = middle.listIterator();
+
+        while (itty.hasNext()) {
+            Zone current = itty.next();
+            for (int i = 0; i < sortedZones.size(); i++) {
+                if (current.getY() < sortedZones.get(i).getY()) {
+                    sortedZones.add(i, current);
+                    itty.remove();
+                    break;
+                }
+            }
+        }
+
+        sortedZones.addAll(middle);
+
+        return sortedZones;
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/service/SpacingService.java

@@ -0,0 +1,56 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service;
+
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.AngleFilter;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Character;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Histogram;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Neighbor;
+
+@Service
+public class SpacingService {
+
+    private static final double SPACING_HISTOGRAM_RESOLUTION = 0.5;
+    private static final double SPACING_HISTOGRAM_SMOOTHING_LENGTH = 2.5;
+    private static final double SPACING_HIST_SMOOTHING_STANDARD_DEVIATION = 0.5;
+    private static final double ANGLE_TOLERANCE = Math.PI / 6;
+
+
+    public double computeCharacterSpacing(List<Character> components) {
+
+        return computeSpacing(components, 0);
+    }
+
+
+    public double computeLineSpacing(List<Character> components) {
+
+        return computeSpacing(components, Math.PI / 2);
+    }
+
+
+    private double computeSpacing(List<Character> components, double angle) {
+
+        double maxDistance = Double.NEGATIVE_INFINITY;
+
+        for (Character component : components) {
+            for (Neighbor neighbor : component.getNeighbors()) {
+                maxDistance = Math.max(maxDistance, neighbor.getDistance());
+            }
+        }
+        Histogram histogram = new Histogram(0, maxDistance, SPACING_HISTOGRAM_RESOLUTION);
+        AngleFilter filter = new AngleFilter(angle - ANGLE_TOLERANCE, angle + ANGLE_TOLERANCE);
+        for (Character component : components) {
+            for (Neighbor neighbor : component.getNeighbors()) {
+                if (filter.matches(neighbor)) {
+                    histogram.add(neighbor.getDistance());
+                }
+            }
+        }
+
+        histogram.gaussianSmooth(SPACING_HISTOGRAM_SMOOTHING_LENGTH, SPACING_HIST_SMOOTHING_STANDARD_DEVIATION);
+        return histogram.getPeakValue();
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/service/ZoneBuilderService.java

@@ -0,0 +1,90 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.service;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.DisjointSets;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Line;
+import com.knecon.fforesight.service.layoutparser.processor.services.docstrum.model.Zone;
+
+@Service
+public class ZoneBuilderService {
+
+    private static final double MIN_HORIZONTAL_DISTANCE_MULTIPLIER = -0.5;
+    private static final double MAX_VERTICAL_DISTANCE_MULTIPLIER = 1.2;
+
+    private static final double MIN_HORIZONTAL_MERGE_DISTANCE_MULTIPLIER = -3.0;
+
+    private static final double MAX_VERTICAL_MERGE_DISTANCE_MULTIPLIER = 0.5;
+
+    private static final double MIN_LINE_SIZE_SCALE = 0.9;
+
+    private static final double MAX_LINE_SIZE_SCALE = 2.5;
+
+    private static final double ANGLE_TOLERANCE = Math.PI / 6;
+
+    public static final int MAX_ZONES = 300;
+
+
+    public List<Zone> buildZones(List<Line> lines, double characterSpacing, double lineSpacing) {
+
+        double minHorizontalDistance = characterSpacing * MIN_HORIZONTAL_DISTANCE_MULTIPLIER;
+        double maxVerticalDistance = lineSpacing * MAX_VERTICAL_DISTANCE_MULTIPLIER;
+        double minHorizontalMergeDistance = characterSpacing * MIN_HORIZONTAL_MERGE_DISTANCE_MULTIPLIER;
+        double maxVerticalMergeDistance = lineSpacing * MAX_VERTICAL_MERGE_DISTANCE_MULTIPLIER;
+
+        DisjointSets<Line> sets = new DisjointSets<>(lines);
+
+        double meanHeight = calculateMeanHeight(lines);
+
+        lines.forEach(outerLine -> //
+                lines.forEach(innerLine -> {
+
+                    double scale = Math.min(outerLine.getHeight(), innerLine.getHeight()) / meanHeight;
+                    scale = Math.max(MIN_LINE_SIZE_SCALE, Math.min(scale, MAX_LINE_SIZE_SCALE));
+
+                    if (!sets.areTogether(outerLine, innerLine) && outerLine.angularDifference(innerLine) <= ANGLE_TOLERANCE) {
+
+                        double horizontalDistance = outerLine.horizontalDistance(innerLine) / scale;
+                        double verticalDistance = outerLine.verticalDistance(innerLine) / scale;
+
+                        if (minHorizontalDistance <= horizontalDistance && verticalDistance <= maxVerticalDistance //
+                                || minHorizontalMergeDistance <= horizontalDistance && verticalDistance <= maxVerticalMergeDistance) {
+                            sets.union(outerLine, innerLine);
+                        }
+                    }
+                }));
+
+        List<Zone> zones = new ArrayList<>();
+        sets.forEach(group -> {
+            zones.add(new Zone(new ArrayList<>(group)));
+        });
+
+        if (zones.size() > MAX_ZONES) {
+            List<Line> oneZoneLines = new ArrayList<>();
+            for (Zone zone : zones) {
+                oneZoneLines.addAll(zone.getLines());
+            }
+            return List.of(new Zone(oneZoneLines));
+        }
+
+        return zones;
+    }
+
+
+    private double calculateMeanHeight(List<Line> lines) {
+
+        double meanHeight = 0.0;
+        double weights = 0.0;
+        for (Line line : lines) {
+            double weight = line.getLength();
+            meanHeight += line.getHeight() * weight;
+            weights += weight;
+        }
+        meanHeight /= weights;
+        return meanHeight;
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/docstrum/utils/DoubleUtils.java

@@ -0,0 +1,18 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.docstrum.utils;
+
+public class DoubleUtils {
+
+    public static int compareDouble(double d1, double d2, double precision) {
+
+        if (Double.isNaN(d1) || Double.isNaN(d2)) {
+            return Double.compare(d1, d2);
+        }
+        if (precision == 0) {
+            precision = 1;
+        }
+        long i1 = Math.round(d1 / precision);
+        long i2 = Math.round(d2 / precision);
+        return Long.valueOf(i1).compareTo(i2);
+    }
+
+}

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/services/visualization/PdfDraw.java

@@ -0,0 +1,270 @@
+package com.knecon.fforesight.service.layoutparser.processor.services.visualization;
+
+import java.awt.Color;
+import java.awt.geom.Point2D;
+import java.awt.geom.Rectangle2D;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.pdfbox.Loader;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.PDPageContentStream;
+import org.apache.pdfbox.pdmodel.font.PDType1Font;
+import org.apache.pdfbox.pdmodel.font.Standard14Fonts;
+import org.apache.pdfbox.util.Matrix;
+import org.springframework.core.io.ClassPathResource;
+
+import com.knecon.fforesight.service.layoutparser.internal.api.data.redaction.NodeType;
+import com.knecon.fforesight.service.layoutparser.processor.model.graph.DocumentTree;
+import com.knecon.fforesight.service.layoutparser.processor.model.graph.nodes.Document;
+import com.knecon.fforesight.service.layoutparser.processor.model.graph.nodes.Page;
+import com.knecon.fforesight.service.layoutparser.processor.model.graph.textblock.AtomicTextBlock;
+import com.knecon.fforesight.service.layoutparser.processor.model.graph.textblock.TextBlock;
+import com.knecon.fforesight.service.layoutparser.processor.model.table.Ruling;
+import com.knecon.fforesight.service.layoutparser.processor.utils.PdfVisualisationUtility;
+import com.knecon.fforesight.service.layoutparser.processor.utils.RectangleTransformations;
+
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.SneakyThrows;
+import lombok.experimental.FieldDefaults;
+import lombok.experimental.UtilityClass;
+
+@UtilityClass
+public class PdfDraw {
+
+    public static void drawRectanglesPerPage(String filename, List<List<Rectangle2D>> rectanglesPerPage, String tmpFileName) throws IOException {
+
+        ClassPathResource pdfResource = new ClassPathResource(filename);
+        try (PDDocument pdDocument = Loader.loadPDF(pdfResource.getFile()); var out = new FileOutputStream(tmpFileName)) {
+            for (int pageNumber = 1; pageNumber < pdDocument.getNumberOfPages() + 1; pageNumber++) {
+                PdfVisualisationUtility.drawRectangle2DList(pdDocument,
+                        pageNumber,
+                        rectanglesPerPage.get(pageNumber - 1),
+                        PdfVisualisationUtility.Options.builder().stroke(true).build());
+            }
+            pdDocument.save(out);
+        }
+
+    }
+
+
+    public static void drawRectanglesPerPageNumberedByLine(String filename, List<List<List<Rectangle2D>>> rectanglesPerPage, String tmpFileName) throws IOException {
+
+        ClassPathResource pdfResource = new ClassPathResource(filename);
+        try (PDDocument pdDocument = Loader.loadPDF(pdfResource.getFile()); var out = new FileOutputStream(tmpFileName)) {
+            for (int pageNumber = 1; pageNumber < pdDocument.getNumberOfPages() + 1; pageNumber++) {
+                var rectanglesOnPage = rectanglesPerPage.get(pageNumber - 1);
+                for (int lineNumber = 0; lineNumber < rectanglesOnPage.size(); lineNumber++) {
+                    var rectanglesInLine = rectanglesOnPage.get(lineNumber);
+                    PdfVisualisationUtility.drawRectangle2DList(pdDocument, pageNumber, rectanglesInLine, PdfVisualisationUtility.Options.builder().stroke(true).build());
+                    double y = Math.min(rectanglesInLine.get(0).getMinY(), rectanglesInLine.get(0).getMaxY());
+                    PdfVisualisationUtility.drawText(String.format("%d", lineNumber),
+                            pdDocument,
+                            new Point2D.Double(rectanglesInLine.get(0).getX() - (5 + (5 * countNumberOfDigits(lineNumber))), y + 2),
+                            pageNumber,
+                            PdfVisualisationUtility.Options.builder().stroke(true).build());
+                }
+            }
+            pdDocument.save(out);
+        }
+
+    }
+
+
+    private static int countNumberOfDigits(int num) {
+
+        int final_num = num;
+        if (final_num == 0) {
+            return 1;
+        }
+        int count = 0;
+        for (; final_num != 0; final_num /= 10) {
+            count++;
+        }
+        return count;
+    }
+
+
+    public static void drawDocumentGraph(PDDocument document, Document documentGraph) {
+
+        documentGraph.getDocumentTree().allEntriesInOrder().forEach(entry -> drawNode(document, entry));
+    }
+
+
+    public static void drawNode(PDDocument document, DocumentTree.Entry entry) {
+
+        Options options = buildStandardOptionsForNodes(entry);
+
+        drawBBoxAndLabelAndNumberOnPage(document, entry, options);
+
+    }
+
+
+    public static void drawTextBlock(PDDocument document, TextBlock textBlock, Options options) {
+
+        textBlock.getAtomicTextBlocks().forEach(atb -> drawAtomicTextBlock(document, atb, options));
+    }
+
+
+    public static void drawAtomicTextBlock(PDDocument document, AtomicTextBlock atomicTextBlock, Options options) {
+
+        drawRectangle2DList(document, atomicTextBlock.getPage().getNumber(), atomicTextBlock.getPositions().stream().toList(), options);
+
+    }
+
+
+    @SneakyThrows
+    private static void drawText(String string, PDDocument document, Point2D location, Integer pageNumber, Options options, boolean rotate) {
+
+        var pdPage = document.getPage(pageNumber - 1);
+        var contentStream = new PDPageContentStream(document, pdPage, PDPageContentStream.AppendMode.APPEND, true);
+
+        contentStream.setNonStrokingColor(options.getStrokeColor());
+        contentStream.setLineWidth(options.getStrokeWidth());
+
+        contentStream.beginText();
+        if (rotate) {
+            contentStream.setTextMatrix(Matrix.getRotateInstance(Math.toRadians(15), (float) location.getX(), (float) location.getY()));
+        } else {
+            contentStream.newLineAtOffset((float) location.getX(), (float) location.getY());
+        }
+        contentStream.setFont(new PDType1Font(Standard14Fonts.FontName.HELVETICA), 10);
+        contentStream.showText(string);
+        contentStream.endText();
+        contentStream.close();
+    }
+
+
+    @SneakyThrows
+    public static void drawRectangle2DList(PDDocument document, int pageNumber, List<Rectangle2D> rectCollection, Options options) {
+
+        var pdPage = document.getPage(pageNumber - 1);
+        drawRectangle2DList(document, rectCollection, options, pdPage);
+    }
+
+
+    private static void drawRectangle2DList(PDDocument document, List<Rectangle2D> rectCollection, Options options, PDPage pdPage) throws IOException {
+
+        var contentStream = new PDPageContentStream(document, pdPage, PDPageContentStream.AppendMode.APPEND, true);
+
+        contentStream.setStrokingColor(options.getStrokeColor());
+        contentStream.setNonStrokingColor(options.getFillColor());
+        contentStream.setLineWidth(options.getStrokeWidth());
+
+        for (var r : rectCollection) {
+            contentStream.addRect((float) r.getMinX(), (float) r.getMinY(), (float) r.getWidth(), (float) r.getHeight());
+
+            if (options.isStroke() && options.isFill()) {
+                contentStream.fillAndStroke();
+            } else if (options.isStroke()) {
+                contentStream.stroke();
+            } else if (options.isFill()) {
+                contentStream.fill();
+            }
+        }
+        contentStream.close();
+    }
+
+
+    @SneakyThrows
+    public static void drawRectanglesAndLinesPerPage(String filename, List<List<Rectangle2D>> list, List<List<Rectangle2D>> rectanglesPerPage, String tmpFileName) {
+
+        ClassPathResource pdfResource = new ClassPathResource(filename);
+        try (PDDocument pdDocument = Loader.loadPDF(pdfResource.getFile()); var out = new FileOutputStream(tmpFileName)) {
+            for (int pageNumber = 1; pageNumber < pdDocument.getNumberOfPages() + 1; pageNumber++) {
+//                PdfVisualisationUtility.drawLine2DList(pdDocument,
+//                        pageNumber,
+//                        list.get(pageNumber - 1),
+//                        PdfVisualisationUtility.Options.builder().stroke(true).build());
+                PdfVisualisationUtility.drawRectangle2DList(pdDocument,
+                        pageNumber,
+                        rectanglesPerPage.get(pageNumber - 1),
+                        PdfVisualisationUtility.Options.builder().stroke(true).build());
+                PdfVisualisationUtility.drawRectangle2DList(pdDocument, pageNumber, list.get(pageNumber - 1), PdfVisualisationUtility.Options.builder().stroke(true).build());
+            }
+            pdDocument.save(out);
+        }
+    }
+
+
+    @SneakyThrows
+    public static void drawLinesPerPage(String filename, List<List<Ruling>> linesPerPage, String tmpFileName) {
+
+        ClassPathResource pdfResource = new ClassPathResource(filename);
+        try (PDDocument pdDocument = Loader.loadPDF(pdfResource.getFile()); var out = new FileOutputStream(tmpFileName)) {
+            for (int pageNumber = 1; pageNumber < pdDocument.getNumberOfPages() + 1; pageNumber++) {
+                PdfVisualisationUtility.drawLine2DList(pdDocument,
+                        pageNumber,
+                        linesPerPage.get(pageNumber - 1),
+                        PdfVisualisationUtility.Options.builder().strokeColor(Color.RED).stroke(true).build());
+            }
+            pdDocument.save(out);
+        }
+    }
+
+
+    @Builder
+    @AllArgsConstructor
+    @Getter
+    @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE)
+    public static class Options {
+
+        boolean stroke;
+        @Builder.Default
+        Color strokeColor = Color.BLACK;
+        @Builder.Default
+        float strokeWidth = 1f;
+
+        boolean fill;
+        @Builder.Default
+        Color fillColor = Color.BLACK;
+
+    }
+
+
+    private static Options buildStandardOptionsForNodes(DocumentTree.Entry entry) {
+
+        return Options.builder().stroke(true).strokeColor(switch (entry.getType()) {
+            case DOCUMENT -> Color.LIGHT_GRAY;
+            case HEADER, FOOTER -> Color.GREEN;
+            case PARAGRAPH -> Color.BLUE;
+            case HEADLINE -> Color.RED;
+            case SECTION -> Color.BLACK;
+            case TABLE -> Color.ORANGE;
+            case TABLE_CELL -> Color.GRAY;
+            case IMAGE -> Color.MAGENTA;
+        }).build();
+    }
+
+
+    private static void drawBBoxAndLabelAndNumberOnPage(PDDocument document, DocumentTree.Entry entry, Options options) {
+
+        Map<Page, Rectangle2D> rectanglesPerPage = entry.getNode().getBBox();
+        for (Page page : rectanglesPerPage.keySet()) {
+            Rectangle2D rectangle2D = rectanglesPerPage.get(page);
+            if (entry.getType() == NodeType.SECTION) {
+                rectangle2D = RectangleTransformations.pad(rectangle2D, 10, 10);
+            }
+            drawRectangle2DList(document, page.getNumber(), List.of(rectangle2D), options);
+            drawText(buildString(entry),
+                    document,
+                    new Point2D.Double(rectangle2D.getMinX(), rectangle2D.getMaxY() + 2),
+                    page.getNumber(),
+                    options,
+                    entry.getType() == NodeType.TABLE_CELL);
+        }
+    }
+
+
+    private static String buildString(DocumentTree.Entry entry) {
+
+        return entry.getNode().getNumberOnPage() + ": " + entry.getTreeId() + ": " + entry.getType();
+    }
+
+}

layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/LayoutparserEnd2EndTest.java

@@ -25,7 +25,9 @@ public class LayoutparserEnd2EndTest extends AbstractTest {
     @SneakyThrows
     public void testLayoutParserEndToEnd() {
 
-        prepareStorage("files/bdr/Wie weiter bei Kristeneinrichtungen.pdf");
+        String s = "（";
+        String s1 = "）";
+        prepareStorage("files/Minimal Examples/WrongOrderPage1.pdf");
         LayoutParsingRequest layoutParsingRequest = buildDefaultLayoutParsingRequest(LayoutParsingType.REDACT_MANAGER);
         LayoutParsingFinishedEvent finishedEvent = layoutParsingPipeline.parseLayoutAndSaveFilesToStorage(layoutParsingRequest);
         Arrays.stream(finishedEvent.message().split("\n")).forEach(log::info);

layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/graph/ViewerDocumentTest.java

@@ -25,7 +25,7 @@ public class ViewerDocumentTest extends BuildDocumentTest {
     @SneakyThrows
     public void testViewerDocument() {
 
-        String fileName = "files/S-Metolachlor_RAR_01_Volume_1_2018-09-06.pdf";
+        String fileName = "files/Plenarprotokoll 1 (keine Druchsache!) (1).pdf";
         String tmpFileName = "/tmp/" + Path.of(fileName).getFileName() + "_VIEWER.pdf";
 
         var documentFile = new ClassPathResource(fileName).getFile();
@@ -35,9 +35,10 @@ public class ViewerDocumentTest extends BuildDocumentTest {
         Document document = buildGraph(fileName, LayoutParsingType.REDACT_MANAGER);
         long start = System.currentTimeMillis();
         layoutGridService.addLayoutGrid(documentFile, document, new File(tmpFileName), true);
-        System.out.printf("Total time: %.2fs%n",  ((float) (System.currentTimeMillis() - start)) / 1000);
+        System.out.printf("Total time: %.2fs%n", ((float) (System.currentTimeMillis() - start)) / 1000);
     }
 
+
     @Test
     @Disabled
     @SneakyThrows
@@ -51,7 +52,11 @@ public class ViewerDocumentTest extends BuildDocumentTest {
         var tableResponse = mapper.readValue(new ClassPathResource(tableFileName).getInputStream(), TableServiceResponse.class);
         var documentFile = new ClassPathResource(fileName).getFile();
 
-        var classificationDocument = layoutParsingPipeline.parseLayout(LayoutParsingType.DOCUMINE, documentFile, new ImageServiceResponse(), tableResponse, Path.of(fileName).getFileName().toFile().toString());
+        var classificationDocument = layoutParsingPipeline.parseLayout(LayoutParsingType.DOCUMINE,
+                documentFile,
+                new ImageServiceResponse(),
+                tableResponse,
+                Path.of(fileName).getFileName().toFile().toString());
         ViewerDocumentService viewerDocumentService = new ViewerDocumentService(null);
         LayoutGridService layoutGridService = new LayoutGridService(viewerDocumentService);
         Document document = DocumentGraphFactory.buildDocumentGraph(classificationDocument);