Combining moving targets with running average

src/main/java/com/elphel/imagej/gpu/GpuQuad.java

@@ -4725,8 +4725,8 @@ public class GpuQuad{ // quad camera description
 	 * works with the negative scales, so the result will be a negative image in the TD.
 	 * @param vector_field sparse array of motion vectors (may be longer, only Vx and Vy used). Null elements
 	 * are allowed, they will be skipped, resultin in null TpTask elements.
-	 * @param offset_scale multiply all vectors by this value when calculatingpixel offsets
-	 * @param magnitude_scale Scale data for accumulation (here positive, will be negated
+	 * @param offset_scale multiply all vectors by this value when calculating pixel offsets
+	 * @param magnitude_scale Scale data for accumulation (here positive, will be negated). If 0 - will use scale=1.0 (no accumulation)
 	 * @param image_width image width in tiles (80 for 640-wide images).
 	 * @return condensed array of TpTask
 	 */
@@ -4735,7 +4735,7 @@ public class GpuQuad{ // quad camera description
 			final double      offset_scale,
 			final double      magnitude_scale,
 			final int         tilesX) {
-		final float fmagnitude_scale = (float) -magnitude_scale;
+		final float fmagnitude_scale = (magnitude_scale==0)? 1.0f : ((float) -magnitude_scale);
 		final int tiles = vector_field.length;
 		final TpTask [] tp_tasks_full = new TpTask [tiles]; 
 		final Thread[] threads = ImageDtt.newThreadArray();

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

@@ -1495,7 +1495,7 @@ public class ImageDtt extends ImageDttCPU {
 	
 	public void setRectilinearReferenceTD(
 			final int                 erase_clt,
-			final float []            fpixels_ref,
+			final float []            fpixels_ref,      // if null, assumes GPU memory is already loaded
 			final int []              wh,               // null (use sensor dimensions) or pair {width, height} in pixels
 			final ImageDttParameters  imgdtt_params,    // Now just extra correlation parameters, later will include, most others
 			final boolean             use_reference_buffer,
@@ -1516,14 +1516,15 @@ public class ImageDtt extends ImageDttCPU {
 				lpf_rgb,
 				globalDebugLevel > 2);
 //		gpuQuad.printConstMem("lpf_data",    true); 
-
 		gpuQuad.setTasks(                  // copy tp_tasks to the GPU memory
 				tp_tasks,                  // TpTask [] tile_tasks,
 				false,                     // use_aux); // boolean use_aux)
 				imgdtt_params.gpu_verify); // boolean verify
-		gpuQuad.setBayerImage(
-				fpixels_ref, // float [] bayer_image,
-				0); // 	int ncam)
+		if (fpixels_ref != null) {
+			gpuQuad.setBayerImage(
+					fpixels_ref, // float [] bayer_image,
+					0); // 	int ncam)
+		}
 		// allocate before execConvertDirect, so it will not be modified
 		boolean allocated = gpuQuad.reAllocateClt(
 				wh, // int []  wh,