Added support of homography motion model into vidostab sample

samples/cpp/videostab.cpp

@@ -65,7 +65,7 @@ void printHelp()
     cout << "OpenCV video stabilizer.\n"
             "Usage: videostab <file_path> [arguments]\n\n"
             "Arguments:\n"
-            "  -m, --model=(transl|transl_and_scale|linear_sim|affine)\n"
+            "  -m, --model=(transl|transl_and_scale|linear_sim|affine|homography)\n"
             "      Set motion model. The default is affine.\n"
             "  --outlier-ratio=<float_number>\n"
             "      Outliers ratio in motion estimation. The default is 0.5.\n"
@@ -232,8 +232,6 @@ int main(int argc, const char **argv)
         if (arg("fps") == "auto") outputFps = source->fps();  else outputFps = argd("fps");
         stabilizer->setFrameSource(source);
 
-        if (arg("load-motions") == "no")
-        {            
         PyrLkRobustMotionEstimator *est = 0;
         if (arg("model") == "transl")
             est = new PyrLkRobustMotionEstimator(TRANSLATION);
@@ -243,6 +241,8 @@ int main(int argc, const char **argv)
             est = new PyrLkRobustMotionEstimator(LINEAR_SIMILARITY);
         else if (arg("model") == "affine")
             est = new PyrLkRobustMotionEstimator(AFFINE);
+        else if (arg("model") == "homography")
+            est = new PyrLkRobustMotionEstimator(HOMOGRAPHY);
         else
         {
             delete est;
@@ -253,9 +253,13 @@ int main(int argc, const char **argv)
         est->setRansacParams(ransac);
         est->setMinInlierRatio(argf("min-inlier-ratio"));
         stabilizer->setMotionEstimator(est);
-        }
-        else
+
+        if (arg("load-motions") != "no")
+        {
+            MotionModel model = stabilizer->motionEstimator()->motionModel();
             stabilizer->setMotionEstimator(new FromFileMotionReader(arg("load-motions")));
+            stabilizer->motionEstimator()->setMotionModel(model);
+        }
 
         if (arg("save-motions") != "no")
             stabilizer->setMotionEstimator(