From 99f29b75a12781cd620811ee8dda2fefd5b41d46 Mon Sep 17 00:00:00 2001
From: Alexey Spizhevoy <no@email>
Date: Fri, 30 Mar 2012 09:44:32 +0000
Subject: [PATCH] Added linear similarity estimation into videostab module

---
 .../include/opencv2/videostab/global_motion.hpp    |  8 +++--
 modules/videostab/src/global_motion.cpp            | 37 ++++++++++++++++++++++
 modules/videostab/src/stabilizer.cpp               |  2 +-
 samples/cpp/videostab.cpp                          |  4 ++-
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/modules/videostab/include/opencv2/videostab/global_motion.hpp b/modules/videostab/include/opencv2/videostab/global_motion.hpp
index d62456d..85a37fe 100644
--- a/modules/videostab/include/opencv2/videostab/global_motion.hpp
+++ b/modules/videostab/include/opencv2/videostab/global_motion.hpp
@@ -57,7 +57,8 @@ enum MotionModel
 {
     TRANSLATION = 0,
     TRANSLATION_AND_SCALE = 1,
-    AFFINE = 2
+    LINEAR_SIMILARITY = 2,
+    AFFINE = 3
 };
 
 CV_EXPORTS Mat estimateGlobalMotionLeastSquares(
@@ -74,9 +75,10 @@ struct CV_EXPORTS RansacParams
     RansacParams(int size, float thresh, float eps, float prob)
         : size(size), thresh(thresh), eps(eps), prob(prob) {}
 
-    static RansacParams affine2dMotionStd() { return RansacParams(6, 0.5f, 0.5f, 0.99f); }
-    static RansacParams translationAndScale2dMotionStd() { return RansacParams(3, 0.5f, 0.5f, 0.99f); }
     static RansacParams translationMotionStd() { return RansacParams(2, 0.5f, 0.5f, 0.99f); }
+    static RansacParams translationAndScale2dMotionStd() { return RansacParams(3, 0.5f, 0.5f, 0.99f); }
+    static RansacParams linearSimilarityMotionStd() { return RansacParams(4, 0.5f, 0.5f, 0.99f); }
+    static RansacParams affine2dMotionStd() { return RansacParams(6, 0.5f, 0.5f, 0.99f); }
 };
 
 CV_EXPORTS Mat estimateGlobalMotionRobust(
diff --git a/modules/videostab/src/global_motion.cpp b/modules/videostab/src/global_motion.cpp
index 94292b3..c522a76 100644
--- a/modules/videostab/src/global_motion.cpp
+++ b/modules/videostab/src/global_motion.cpp
@@ -107,6 +107,41 @@ static Mat estimateGlobMotionLeastSquaresTranslationAndScale(
 }
 
 
+static Mat estimateGlobMotionLeastSquaresLinearSimilarity(
+        int npoints, const Point2f *points0, const Point2f *points1, float *rmse)
+{
+    Mat_<float> A(2*npoints, 4), b(2*npoints, 1);
+    float *a0, *a1;
+    Point2f p0, p1;
+
+    for (int i = 0; i < npoints; ++i)
+    {
+        a0 = A[2*i];
+        a1 = A[2*i+1];
+        p0 = points0[i];
+        p1 = points1[i];
+        a0[0] = p0.x; a0[1] = p0.y; a0[2] = 1;  a0[3] = 0;
+        a1[0] = p0.y; a1[1] = -p0.x; a1[2] = 0; a1[3] = 1;
+        b(2*i,0) = p1.x;
+        b(2*i+1,0) = p1.y;
+    }
+
+    Mat_<float> sol;
+    solve(A, b, sol, DECOMP_SVD);
+
+    if (rmse)
+        *rmse = static_cast<float>(norm(A*sol, b, NORM_L2) / sqrt(static_cast<double>(npoints)));
+
+    Mat_<float> M = Mat::eye(3, 3, CV_32F);
+    M(0,0) = M(1,1) = sol(0,0);
+    M(0,1) = sol(1,0);
+    M(1,0) = -sol(1,0);
+    M(0,2) = sol(2,0);
+    M(1,2) = sol(3,0);
+    return M;
+}
+
+
 static Mat estimateGlobMotionLeastSquaresAffine(
         int npoints, const Point2f *points0, const Point2f *points1, float *rmse)
 {
@@ -149,6 +184,7 @@ Mat estimateGlobalMotionLeastSquares(
     typedef Mat (*Impl)(int, const Point2f*, const Point2f*, float*);
     static Impl impls[] = { estimateGlobMotionLeastSquaresTranslation,
                             estimateGlobMotionLeastSquaresTranslationAndScale,
+                            estimateGlobMotionLeastSquaresLinearSimilarity,
                             estimateGlobMotionLeastSquaresAffine };
 
     int npoints = static_cast<int>(points0.size());
@@ -165,6 +201,7 @@ Mat estimateGlobalMotionRobust(
     typedef Mat (*Impl)(int, const Point2f*, const Point2f*, float*);
     static Impl impls[] = { estimateGlobMotionLeastSquaresTranslation,
                             estimateGlobMotionLeastSquaresTranslationAndScale,
+                            estimateGlobMotionLeastSquaresLinearSimilarity,
                             estimateGlobMotionLeastSquaresAffine };
 
     const int npoints = static_cast<int>(points0.size());
diff --git a/modules/videostab/src/stabilizer.cpp b/modules/videostab/src/stabilizer.cpp
index 9dab8c0..93868c2 100644
--- a/modules/videostab/src/stabilizer.cpp
+++ b/modules/videostab/src/stabilizer.cpp
@@ -266,7 +266,7 @@ void OnePassStabilizer::stabilizeFrame()
 TwoPassStabilizer::TwoPassStabilizer()
 {
     setMotionStabilizer(new GaussianMotionFilter());
-    setEstimateTrimRatio(true);
+    setEstimateTrimRatio(false);
     resetImpl();
 }
 
diff --git a/samples/cpp/videostab.cpp b/samples/cpp/videostab.cpp
index 0c84701..cbcc22a 100644
--- a/samples/cpp/videostab.cpp
+++ b/samples/cpp/videostab.cpp
@@ -121,7 +121,7 @@ void printHelp()
     cout << "OpenCV video stabilizer.\n"
             "Usage: videostab <file_path> [arguments]\n\n"
             "Arguments:\n"
-            "  -m, --model=(transl|transl_and_scale|affine)\n"
+            "  -m, --model=(transl|transl_and_scale|linear_sim|affine)\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"
@@ -259,6 +259,8 @@ int main(int argc, const char **argv)
             motionEstimator->setMotionModel(TRANSLATION);
         else if (cmd.get<string>("model") == "transl_and_scale")
             motionEstimator->setMotionModel(TRANSLATION_AND_SCALE);
+        else if (cmd.get<string>("model") == "linear_sim")
+            motionEstimator->setMotionModel(LINEAR_SIMILARITY);
         else if (cmd.get<string>("model") == "affine")
             motionEstimator->setMotionModel(AFFINE);
         else if (!cmd.get<string>("model").empty())
-- 
2.7.4