Changeset 34199 for trunk/psModules/src/objects/pmFootprintFind.c

Timestamp:

Jul 24, 2012, 3:35:32 PM (14 years ago)

Author:

bills

Message:

When building footprints save the highest id in an alias chain in the current span.
Searching for aliases is more efficient that way. This speeds up the analysis if
really complex footprints during pmFootprintCullPeaks when the input image has a lot
of NAN pixels.

File:

• trunk/psModules/src/objects/pmFootprintFind.c (modified) (4 diffs)

trunk/psModules/src/objects/pmFootprintFind.c

@@ -24 +24 @@
 
 // XXX EAM : why use WSPAN in here rather than pmSpan?
+// XXX WES : can't use pmSpan because does not have an id
 typedef struct {                        /* run-length code for part of object*/
    int id;                              /* ID for object */
@@ -114 +115 @@
 
        in_span = 0;                      /* not in a span */
+       int id_last_connection = 0;
        for (j = 0; j < numCols; j++) {
            double pixVal = floatImg->data.F32[i][j]; // Value of pixel
+           // If pixVal is less than threshold and we are working on a, span end it.
            if (pixVal < threshold) {
+               // below threshold. If in a span close it out
                if (in_span) {
                    if(nspan >= size_spans) {
@@ -130 +134 @@
 
                    in_span = 0;
+                   id_last_connection = 0;
                }
            } else {                       /* a pixel to fix */
+               // Above theshold. There are 5 choices for the id of this pixel based on whether they are
+               // part of a span (non-zero)
+               // This diagram shows the priority which we check
+               //       
+               //                       col
+               //                   j-1   j   j+1
+               // row i              1    5 
+               // row i + 1          2    3    4
+               //
+               // In case 4 we have a pixel that is not connected to the left are connecting with 
+               // an existing span so need to identify whether it is connected
+               // to the same footprint as the current span (if we are in one)
                if(idc[j - 1] != 0) {
                    id = idc[j - 1];
@@ -157 +174 @@
                 * Do we need to merge ID numbers? If so, make suitable entries in aliases[]
                 */
-               if(idp[j + 1] != 0 && idp[j + 1] != id) {
-                   aliases[resolve_alias(aliases, idp[j + 1])] =
-                       resolve_alias(aliases, id);
-
-                   idc[j] = id = idp[j + 1];
+               if (idp[j + 1] != 0 && idp[j + 1] != id && idp[j + 1] != id_last_connection) {
+                   int resolved_lower_right = resolve_alias(aliases, idp[j + 1]);
+                   int resolved_current = resolve_alias(aliases, id);
+                   aliases[resolved_lower_right] = resolved_current;
+
+                   // now we choose the id to continue to use to set pixels in the current span.
+                   // We choose the higher value because future alias resolutions will be faster
+                   // since the alias chain goes from lower ids to higher. This is about 4 times
+                   // faster for complex footprints.
+                   if (resolved_current <= idp[j + 1]) {
+                       idc[j] = id = idp[j + 1];
+                       id_last_connection = 0;
+                   } else {
+                       idc[j] = id = resolved_current;
+                       id_last_connection = idp[j + 1];
+                   }
                }
            }