Staff lines are now less impacted by isolated chunks

app/src/main/java/org/audiveris/omr/glyph/dynamic/CurvedFilament.java

@@ -60,7 +60,7 @@ public class CurvedFilament
     /** Typical length between points. */
     protected final int segmentLength;
 
-    /** Absolute defining points (including start & stop points). */
+    /** Absolute defining points (including start and stop points). */
     protected List<Point2D> points;
 
     /** Curved line across all defining points. */
@@ -88,37 +88,49 @@ public CurvedFilament (int interline,
     //-------------//
     /**
      * Compute cached data: curve, startPoint, stopPoint, slope.
+     * <p>
      * Curve goes from startPoint to stopPoint through intermediate points rather regularly spaced.
+     * <p>
+     * At each intermediate location, a probe is used to compute the centroid of contained pixels,
+     * and then define the intermediate point.
+     * Since the line expected thickness varies with the filament at hand, we must be rather
+     * conservative regarding the minimum probe weight.
+     * We thus use a simple fraction of the probe width.
      */
     @Override
     public void computeLine ()
     {
         try {
-            /** Width of window to retrieve pixels */
-            int probeWidth = InterlineScale.toPixels(interline, Filament.getProbeWidth());
+            // Width and minWeight of window to retrieve pixels
+            final int probeWidth = InterlineScale.toPixels(interline, Filament.getProbeWidth());
+            final int minWeight = Math.max(
+                    1,
+                    InterlineScale.toPixels(interline, Filament.getProbeMinWeight()));
 
             // We need a rough orientation right now
-            Orientation orientation = getRoughOrientation();
-            Point2D orientedStart = (startPoint == null) ? null : orientation.oriented(startPoint);
-            Point2D orientedStop = (stopPoint == null) ? null : orientation.oriented(stopPoint);
-            Rectangle oBounds = orientation.oriented(getBounds());
-            double oStart = (orientedStart != null) ? orientedStart.getX() : oBounds.x;
-            double oStop = (orientedStop != null) ? orientedStop.getX()
+            final Orientation orientation = getRoughOrientation();
+            final Point2D orientedStart = (startPoint == null) ? null
+                    : orientation.oriented(startPoint);
+            final Point2D orientedStop = (stopPoint == null) ? null
+                    : orientation.oriented(stopPoint);
+            final Rectangle oBounds = orientation.oriented(getBounds());
+            final double oStart = (orientedStart != null) ? orientedStart.getX() : oBounds.x;
+            final double oStop = (orientedStop != null) ? orientedStop.getX()
                     : (oBounds.x + (oBounds.width - 1));
-            double length = oStop - oStart + 1;
+            final double length = oStop - oStart + 1;
 
-            Rectangle oProbe = new Rectangle(oBounds);
+            final Rectangle oProbe = new Rectangle(oBounds);
             oProbe.x = (int) Math.ceil(oStart);
             oProbe.width = probeWidth;
 
             // Determine the number of segments and their precise length
-            int segCount = (int) Math.rint(length / segmentLength);
-            double segLength = length / segCount;
-            List<Point2D> newPoints = new ArrayList<>(segCount + 1);
+            final int segCount = (int) Math.rint(length / segmentLength);
+            final double segLength = length / segCount;
+            final List<Point2D> newPoints = new ArrayList<>(segCount + 1);
 
-            // First point
+            // First point (minimum weight: 1)
             if (startPoint == null) {
-                Point2D p = orientation.oriented(getCentroid(orientation.absolute(oProbe)));
+                final Point2D p = orientation.oriented(getCentroid(orientation.absolute(oProbe)));
                 startPoint = orientation.absolute(new Point2D.Double(oStart, p.getY()));
             }
 
@@ -128,19 +140,20 @@ public void computeLine ()
             for (int i = 1; i < segCount; i++) {
                 oProbe.x = (int) Math.rint(oStart + (i * segLength));
 
-                Point2D pt = getCentroid(orientation.absolute(oProbe));
+                // Here we can impose a true minimum weight
+                final Point2D pt = getCentroid(orientation.absolute(oProbe), minWeight);
 
-                // If, unfortunately, we are in a filament hole, just skip it
+                // If, unfortunately, we are in a filament "hole", we can just skip it
                 if (pt != null) {
                     newPoints.add(pt);
                 }
             }
 
-            // Last point
+            // Last point (minimum weight: 1)
             if (stopPoint == null) {
                 oProbe.x = (int) Math.floor(oStop - oProbe.width + 1);
 
-                Point2D p = orientation.oriented(getCentroid(orientation.absolute(oProbe)));
+                final Point2D p = orientation.oriented(getCentroid(orientation.absolute(oProbe)));
                 stopPoint = orientation.absolute(new Point2D.Double(oStop, p.getY()));
             }
 

app/src/main/java/org/audiveris/omr/glyph/dynamic/Filament.java

@@ -275,6 +275,19 @@ public static Scale.Fraction getProbeWidth ()
         return constants.probeWidth;
     }
 
+    //-------------------//
+    // getProbeMinWeight //
+    //-------------------//
+    /**
+     * Report the minimum weight in the window used to determine filament position
+     *
+     * @return the scale-independent probe minimum weight
+     */
+    public static Scale.Fraction getProbeMinWeight ()
+    {
+        return constants.probeMinWeight;
+    }
+
     //~ Inner Classes ------------------------------------------------------------------------------
 
     //-----------//
@@ -286,5 +299,9 @@ private static class Constants
         private final Scale.Fraction probeWidth = new Scale.Fraction(
                 0.5,
                 "Width of probing window to retrieve filament ordinate");
+
+        private final Scale.Fraction probeMinWeight = new Scale.Fraction(
+                0.2,
+                "Minimum weight in probing window to validate filament ordinate");
     }
 }

app/src/main/java/org/audiveris/omr/glyph/dynamic/FilamentFactory.java

@@ -1088,7 +1088,7 @@ private static class Constants
                 "Minimum length for a section to be considered as core");
 
         private final Scale.Fraction maxOverlapDeltaPos = new Scale.Fraction(
-                0.4, // Was 0.5 which led to half notes bowing the underlying staff line
+                0.25, // Was 0.5 which led to half notes bowing the underlying staff line
                 "Maximum delta position between two overlapping filaments");
 
         private final Scale.Fraction maxCoordGap = new Scale.Fraction(

app/src/main/java/org/audiveris/omr/glyph/dynamic/SectionCompound.java

@@ -245,13 +245,32 @@ public Point getCentroid ()
      */
     public Point2D getCentroid (Rectangle roi)
     {
-        Barycenter barycenter = new Barycenter();
+        return getCentroid(roi, 1);
+    }
+
+    //-------------//
+    // getCentroid //
+    //-------------//
+    /**
+     * Report the validated glyph absolute centroid (mass center) of all pixels found in the
+     * provided absolute ROI if any.
+     *
+     * @param roi       the region of interest, if null all symbol pixels are considered
+     * @param minWeight minimum weight in region of interest to validate the centroid
+     * @return the absolute mass center point
+     */
+    public Point2D getCentroid (Rectangle roi,
+                                int minWeight)
+    {
+        final Barycenter barycenter = new Barycenter();
 
         for (Section section : getMembers()) {
             section.cumulate(barycenter, roi);
         }
 
-        if (barycenter.getWeight() != 0) {
+        final double w = barycenter.getWeight();
+
+        if (w >= minWeight) {
             return new Point2D.Double(barycenter.getX(), barycenter.getY());
         } else {
             return null;

app/src/main/java/org/audiveris/omr/sheet/grid/BarsRetriever.java

@@ -517,8 +517,7 @@ private Filament buildSerifFilament (Staff staff,
             Collections.sort(
                     compounds,
                     (SectionCompound g1,
-                     SectionCompound g2) ->
-                    {
+                     SectionCompound g2) -> {
                         double d1 = PointUtil.length(GeoUtil.vectorOf(g1.getCentroid(), vertex));
                         double d2 = PointUtil.length(GeoUtil.vectorOf(g2.getCentroid(), vertex));
 

app/src/main/java/org/audiveris/omr/sheet/grid/StaffFilament.java

@@ -76,9 +76,10 @@ public class StaffFilament
     //~ Constructors -------------------------------------------------------------------------------
 
     /**
-     * Creates a new LineFilament object.
-     * Nota: this constructor is needed for FilamentFactory which calls this
-     * kind of constructor via a newInstance() method.
+     * Creates a new <code>StaffFilament</code> object.
+     * <p>
+     * NOTA: this constructor is needed for {@link FilamentFactory} which calls this kind of
+     * constructor via a newInstance() method.
      *
      * @param interline scaling data
      */