Fixed an issue with weight assignment causing the resulting GMM weights to be…

Fixed an issue with weight assignment causing the resulting GMM weights to be unsorted in the CUDA and OCL versions of BackgroundSubtractorMOG2

modules/gpu/src/cuda/bgfg_mog.cu

@@ -489,7 +489,7 @@ namespace cv { namespace gpu { namespace device
             {
                 //need only weight if fit is found
                 float weight = alpha1 * gmm_weight(mode * frame.rows + y, x) + prune;
-
+                int swap_count = 0;
                 //fit not found yet
                 if (!fitsPDF)
                 {
@@ -540,6 +540,7 @@ namespace cv { namespace gpu { namespace device
                             if (weight < gmm_weight((i - 1) * frame.rows + y, x))
                                 break;
 
+                            swap_count++;
                             //swap one up
                             swap(gmm_weight, x, y, i - 1, frame.rows);
                             swap(gmm_variance, x, y, i - 1, frame.rows);
@@ -557,7 +558,7 @@ namespace cv { namespace gpu { namespace device
                     nmodes--;
                 }
 
-                gmm_weight(mode * frame.rows + y, x) = weight; //update weight by the calculated value
+                gmm_weight((mode - swap_count) * frame.rows + y, x) = weight; //update weight by the calculated value
                 totalWeight += weight;
             }
 

modules/ocl/src/opencl/bgfg_mog.cl

@@ -376,7 +376,7 @@ __kernel void mog2_kernel(__global T_FRAME * frame, __global int* fgmask, __glob
         for (int mode = 0; mode < nmodes; ++mode)
         {
             float _weight = alpha1 * weight[(mode * frame_row + y) * weight_step + x] + prune;
-
+            int swap_count = 0;
             if (!fitsPDF)
             {
                 float var = variance[(mode * frame_row + y) * var_step + x];
@@ -404,6 +404,7 @@ __kernel void mog2_kernel(__global T_FRAME * frame, __global int* fgmask, __glob
                     {
                         if (_weight < weight[((i - 1) * frame_row + y) * weight_step + x])
                             break;
+                        swap_count++;
                         swap(weight, x, y, i - 1, frame_row, weight_step);
                         swap(variance, x, y, i - 1, frame_row, var_step);
                         #if defined (CN1)
@@ -421,7 +422,7 @@ __kernel void mog2_kernel(__global T_FRAME * frame, __global int* fgmask, __glob
                 nmodes--;
             }
 
-            weight[(mode * frame_row + y) * weight_step + x] = _weight; //update weight by the calculated value
+            weight[((mode - swap_count) * frame_row + y) * weight_step + x] = _weight; //update weight by the calculated value
             totalWeight += _weight;
         }