depth map BG - added switching to nearest

src/main/java/com/elphel/imagej/tileprocessor/BiQuadParameters.java

@@ -255,6 +255,7 @@ public class BiQuadParameters {
 	public double  mll_min_disp_change_lma =   0.003; // stop re-measure when difference is below, LMA, 120 pairs
 	public int     mll_max_refines_lma =       4;
 	public int     mll_max_refines_bg =        5;
+	public int     mll_max_bg_nearest =        1; // number of selecting BG until switching to "nearest" to prevent switching to BG of BG
 	
 	
 	public boolean mll_generate_scene_outlines = false; // Uses 2 GB - change format, add dimensions (separate color for ref)
@@ -700,6 +701,8 @@ public class BiQuadParameters {
 				"Abandon disparity refinement for tiles where disparity does not converge after this number of passes");
 		gd.addNumericField("Number of BG disparity refine passes (final, 120 pairs with LMA)",                     this.mll_max_refines_bg,  0,3,"",
 				"Measure BG disparity for the tiles that have dual correlation maximums");
+		gd.addNumericField("Number of BG passes until switching to the \"nearest\" selection",                     this.mll_max_bg_nearest,  0,3,"",
+				"only for the first BG passes select BG, later switch to \"nearest\" selection to prevent cascade FG->BG,... FG->BG switching");
 		gd.addCheckbox    ("Generate scene outlines",                                                              this.mll_generate_scene_outlines,
 				"Generate and save scene outlines for scene series (need to change format, it is 2GB with uncompressed Tiff)");
 		
@@ -1003,6 +1006,7 @@ public class BiQuadParameters {
 		this.mll_min_disp_change_lma=       gd.getNextNumber();
 		this.mll_max_refines_lma=     (int) gd.getNextNumber();
 		this.mll_max_refines_bg=      (int) gd.getNextNumber();
+		this.mll_max_bg_nearest=      (int) gd.getNextNumber();
 		this.mll_generate_scene_outlines=   gd.getNextBoolean();
 		
 		this.mll_add_combo=                 gd.getNextBoolean();
@@ -1253,6 +1257,7 @@ public class BiQuadParameters {
 		properties.setProperty(prefix+"mll_min_disp_change_lma",    this.mll_min_disp_change_lma+"");
 		properties.setProperty(prefix+"mll_max_refines_lma",        this.mll_max_refines_lma+"");
 		properties.setProperty(prefix+"mll_max_refines_bg",         this.mll_max_refines_bg+"");
+		properties.setProperty(prefix+"mll_max_bg_nearest",         this.mll_max_bg_nearest+"");
 		properties.setProperty(prefix+"mll_generate_scene_outlines",this.mll_generate_scene_outlines+"");
 		
 		properties.setProperty(prefix+"mll_add_combo",             this.mll_add_combo+"");
@@ -1500,6 +1505,7 @@ public class BiQuadParameters {
 		if (properties.getProperty(prefix+"mll_min_disp_change_lma")!=null) this.mll_min_disp_change_lma=Double.parseDouble(properties.getProperty(prefix+"mll_min_disp_change_lma"));
 		if (properties.getProperty(prefix+"mll_max_refines_lma")!=null)     this.mll_max_refines_lma=Integer.parseInt(properties.getProperty(prefix+"mll_max_refines_lma"));
 		if (properties.getProperty(prefix+"mll_max_refines_bg")!=null)      this.mll_max_refines_bg=Integer.parseInt(properties.getProperty(prefix+"mll_max_refines_bg"));
+		if (properties.getProperty(prefix+"mll_max_bg_nearest")!=null)      this.mll_max_bg_nearest=Integer.parseInt(properties.getProperty(prefix+"mll_max_bg_nearest"));
 		if (properties.getProperty(prefix+"mll_generate_scene_outlines")!=null) this.mll_generate_scene_outlines=Boolean.parseBoolean(properties.getProperty(prefix+"mll_generate_scene_outlines"));
 		
 		if (properties.getProperty(prefix+"mll_add_combo")!=null)           this.mll_add_combo=Boolean.parseBoolean(properties.getProperty(prefix+"mll_add_combo"));
@@ -1747,6 +1753,7 @@ public class BiQuadParameters {
 		bqp.mll_min_disp_change_lma =   this.mll_min_disp_change_lma;
 		bqp.mll_max_refines_lma =       this.mll_max_refines_lma;
 		bqp.mll_max_refines_bg =        this.mll_max_refines_bg;
+		bqp.mll_max_bg_nearest =        this.mll_max_bg_nearest;
 		bqp.mll_generate_scene_outlines = this.mll_generate_scene_outlines;
 		
 		bqp.mll_add_combo =             this.mll_add_combo;

src/main/java/com/elphel/imagej/tileprocessor/OpticalFlow.java

@@ -4437,6 +4437,11 @@ public class OpticalFlow {
 			} else if (nrefine == (clt_parameters.rig.mll_max_refines_pre + clt_parameters.rig.mll_max_refines_lma + 1)) {
 				clt_parameters.img_dtt.bimax_dual_only =    false; // not just dual only
 			}
+			
+			if (nrefine == (clt_parameters.rig.mll_max_refines_pre + clt_parameters.rig.mll_max_refines_lma + clt_parameters.rig.mll_max_bg_nearest)) {
+				clt_parameters.img_dtt.bimax_combine_mode = Correlation2d.CAMEL_NEAREST;
+			}
+			
 			int mcorr_sel = Correlation2d.corrSelEncode(clt_parameters.img_dtt,num_sensors);
 			double [][] disparity_map = 
 					correlateInterscene(