Merge pull request #12827 from hrnr:stitching_4

[evolution] Stitching for OpenCV 4.0

* stitching: wrap Stitcher::create for bindings

* provide method for consistent stitcher usage across languages

* samples: add python stitching sample

* port cpp stitching sample to python

* stitching: consolidate Stitcher create methods

* remove Stitcher::createDefault, it returns Stitcher, not Ptr<Stitcher> -> inconsistent API
* deprecate cv::createStitcher and cv::createStitcherScans in favor of Stitcher::create

* stitching: avoid anonymous enum in Stitcher

* ORIG_RESOL should be double
* add documentatiton

* stitching: improve documentation in Stitcher

* stitching: expose estimator in Stitcher

* remove ABI hack

* stitching: drop try_use_gpu flag

* OCL will be used automatically through T-API in OCL-enable paths
* CUDA won't be used unless user sets CUDA-enabled classes manually

* stitching: drop FeaturesFinder

* use Feature2D instead of FeaturesFinder
* interoperability with features2d module
* detach from dependency on xfeatures2d

* features2d: fix compute and detect to work with UMat vectors

* correctly pass UMats as UMats to allow OCL paths
* support vector of UMats as output arg

* stitching: use nearest interpolation for resizing masks

* fix warnings

modules/features2d/src/feature2d.cpp

@@ -71,29 +71,38 @@ void Feature2D::detect( InputArray image,
 }
 
 
-void Feature2D::detect( InputArrayOfArrays _images,
+void Feature2D::detect( InputArrayOfArrays images,
                         std::vector<std::vector<KeyPoint> >& keypoints,
-                        InputArrayOfArrays _masks )
+                        InputArrayOfArrays masks )
 {
     CV_INSTRUMENT_REGION();
 
-    vector<Mat> images, masks;
+    int nimages = (int)images.total();
 
-    _images.getMatVector(images);
-    size_t i, nimages = images.size();
-
-    if( !_masks.empty() )
+    if (!masks.empty())
     {
-        _masks.getMatVector(masks);
-        CV_Assert(masks.size() == nimages);
+        CV_Assert(masks.total() == (size_t)nimages);
     }
 
     keypoints.resize(nimages);
 
-    for( i = 0; i < nimages; i++ )
+    if (images.isMatVector())
+    {
+       for (int i = 0; i < nimages; i++)
+       {
+           detect(images.getMat(i), keypoints[i], masks.empty() ? noArray() : masks.getMat(i));
+       }
+    }
+    else
     {
-        detect(images[i], keypoints[i], masks.empty() ? Mat() : masks[i] );
+        // assume UMats
+        for (int i = 0; i < nimages; i++)
+        {
+            detect(images.getUMat(i), keypoints[i], masks.empty() ? noArray() : masks.getUMat(i));
+        }
     }
+
+
 }
 
 /*
@@ -116,29 +125,40 @@ void Feature2D::compute( InputArray image,
     detectAndCompute(image, noArray(), keypoints, descriptors, true);
 }
 
-void Feature2D::compute( InputArrayOfArrays _images,
+void Feature2D::compute( InputArrayOfArrays images,
                          std::vector<std::vector<KeyPoint> >& keypoints,
-                         OutputArrayOfArrays _descriptors )
+                         OutputArrayOfArrays descriptors )
 {
     CV_INSTRUMENT_REGION();
 
-    if( !_descriptors.needed() )
+    if( !descriptors.needed() )
         return;
 
-    vector<Mat> images;
-
-    _images.getMatVector(images);
-    size_t i, nimages = images.size();
+    int nimages = (int)images.total();
 
-    CV_Assert( keypoints.size() == nimages );
-    CV_Assert( _descriptors.kind() == _InputArray::STD_VECTOR_MAT );
-
-    vector<Mat>& descriptors = *(vector<Mat>*)_descriptors.getObj();
-    descriptors.resize(nimages);
-
-    for( i = 0; i < nimages; i++ )
+    CV_Assert( keypoints.size() == (size_t)nimages );
+    // resize descriptors to appropriate size and compute
+    if (descriptors.isMatVector())
+    {
+        vector<Mat>& vec = *(vector<Mat>*)descriptors.getObj();
+        vec.resize(nimages);
+        for (int i = 0; i < nimages; i++)
+        {
+            compute(images.getMat(i), keypoints[i], vec[i]);
+        }
+    }
+    else if (descriptors.isUMatVector())
+    {
+        vector<UMat>& vec = *(vector<UMat>*)descriptors.getObj();
+        vec.resize(nimages);
+        for (int i = 0; i < nimages; i++)
+        {
+            compute(images.getUMat(i), keypoints[i], vec[i]);
+        }
+    }
+    else
     {
-        compute(images[i], keypoints[i], descriptors[i]);
+        CV_Error(Error::StsBadArg, "descriptors must be vector<Mat> or vector<UMat>");
     }
 }
 

modules/python/test/test_stitching.py

@@ -10,7 +10,7 @@ class stitching_test(NewOpenCVTests):
         img1 = self.get_sample('stitching/a1.png')
         img2 = self.get_sample('stitching/a2.png')
 
-        stitcher = cv.createStitcher(False)
+        stitcher = cv.Stitcher.create(cv.Stitcher_PANORAMA)
         (_result, pano) = stitcher.stitch((img1, img2))
 
         #cv.imshow("pano", pano)

modules/stitching/include/opencv2/stitching.hpp

@@ -113,6 +113,10 @@ namespace cv {
 A basic example on image stitching
 */
 
+/** @example samples/python/stitching.py
+A basic example on image stitching in Python.
+*/
+
 /** @example samples/cpp/stitching_detailed.cpp
 A detailed example on image stitching
 */
@@ -124,15 +128,22 @@ be able to achieve higher stitching stability and quality of the final images at
 familiar with the theory is recommended.
 
 @note
-   -   A basic example on image stitching can be found at
+-   A basic example on image stitching can be found at
     opencv_source_code/samples/cpp/stitching.cpp
-    -   A detailed example on image stitching can be found at
+-   A basic example on image stitching in Python can be found at
+    opencv_source_code/samples/python/stitching.py
+-   A detailed example on image stitching can be found at
     opencv_source_code/samples/cpp/stitching_detailed.cpp
  */
 class CV_EXPORTS_W Stitcher
 {
 public:
-    enum { ORIG_RESOL = -1 };
+    /**
+     * When setting a resolution for stitching, this values is a placeholder
+     * for preserving the original resolution.
+     */
+    static constexpr const double ORIG_RESOL = -1.0;
+
     enum Status
     {
         OK = 0,
@@ -140,6 +151,7 @@ public:
         ERR_HOMOGRAPHY_EST_FAIL = 2,
         ERR_CAMERA_PARAMS_ADJUST_FAIL = 3
     };
+
     enum Mode
     {
         /** Mode for creating photo panoramas. Expects images under perspective
@@ -157,22 +169,14 @@ public:
 
     };
 
-   // Stitcher() {}
-    /** @brief Creates a stitcher with the default parameters.
-
-    @param try_use_gpu Flag indicating whether GPU should be used whenever it's possible.
-    @return Stitcher class instance.
-     */
-    static Stitcher createDefault(bool try_use_gpu = false);
     /** @brief Creates a Stitcher configured in one of the stitching modes.
 
     @param mode Scenario for stitcher operation. This is usually determined by source of images
     to stitch and their transformation. Default parameters will be chosen for operation in given
     scenario.
-    @param try_use_gpu Flag indicating whether GPU should be used whenever it's possible.
     @return Stitcher class instance.
      */
-    static Ptr<Stitcher> create(Mode mode = PANORAMA, bool try_use_gpu = false);
+    CV_WRAP static Ptr<Stitcher> create(Mode mode = Stitcher::PANORAMA);
 
     CV_WRAP double registrationResol() const { return registr_resol_; }
     CV_WRAP void setRegistrationResol(double resol_mpx) { registr_resol_ = resol_mpx; }
@@ -192,9 +196,9 @@ public:
     detail::WaveCorrectKind waveCorrectKind() const { return wave_correct_kind_; }
     void setWaveCorrectKind(detail::WaveCorrectKind kind) { wave_correct_kind_ = kind; }
 
-    Ptr<detail::FeaturesFinder> featuresFinder() { return features_finder_; }
-    const Ptr<detail::FeaturesFinder> featuresFinder() const { return features_finder_; }
-    void setFeaturesFinder(Ptr<detail::FeaturesFinder> features_finder)
+    Ptr<Feature2D> featuresFinder() { return features_finder_; }
+    const Ptr<Feature2D> featuresFinder() const { return features_finder_; }
+    void setFeaturesFinder(Ptr<Feature2D> features_finder)
         { features_finder_ = features_finder; }
 
     Ptr<detail::FeaturesMatcher> featuresMatcher() { return features_matcher_; }
@@ -214,12 +218,10 @@ public:
     void setBundleAdjuster(Ptr<detail::BundleAdjusterBase> bundle_adjuster)
         { bundle_adjuster_ = bundle_adjuster; }
 
-    /* TODO OpenCV ABI 4.x
     Ptr<detail::Estimator> estimator() { return estimator_; }
     const Ptr<detail::Estimator> estimator() const { return estimator_; }
     void setEstimator(Ptr<detail::Estimator> estimator)
         { estimator_ = estimator; }
-    */
 
     Ptr<WarperCreator> warper() { return warper_; }
     const Ptr<WarperCreator> warper() const { return warper_; }
@@ -238,18 +240,16 @@ public:
     const Ptr<detail::Blender> blender() const { return blender_; }
     void setBlender(Ptr<detail::Blender> b) { blender_ = b; }
 
-    /** @overload */
-    CV_WRAP Status estimateTransform(InputArrayOfArrays images);
     /** @brief These functions try to match the given images and to estimate rotations of each camera.
 
     @note Use the functions only if you're aware of the stitching pipeline, otherwise use
     Stitcher::stitch.
 
     @param images Input images.
-    @param rois Region of interest rectangles.
+    @param masks Masks for each input image specifying where to look for keypoints (optional).
     @return Status code.
      */
-    Status estimateTransform(InputArrayOfArrays images, const std::vector<std::vector<Rect> > &rois);
+    CV_WRAP Status estimateTransform(InputArrayOfArrays images, InputArrayOfArrays masks = noArray());
 
     /** @overload */
     CV_WRAP Status composePanorama(OutputArray pano);
@@ -271,19 +271,17 @@ public:
     /** @brief These functions try to stitch the given images.
 
     @param images Input images.
-    @param rois Region of interest rectangles.
+    @param masks Masks for each input image specifying where to look for keypoints (optional).
     @param pano Final pano.
     @return Status code.
      */
-    Status stitch(InputArrayOfArrays images, const std::vector<std::vector<Rect> > &rois, OutputArray pano);
+    CV_WRAP Status stitch(InputArrayOfArrays images, InputArrayOfArrays masks, OutputArray pano);
 
     std::vector<int> component() const { return indices_; }
     std::vector<detail::CameraParams> cameras() const { return cameras_; }
     CV_WRAP double workScale() const { return work_scale_; }
 
 private:
-    //Stitcher() {}
-
     Status matchImages();
     Status estimateCameraParams();
 
@@ -291,13 +289,11 @@ private:
     double seam_est_resol_;
     double compose_resol_;
     double conf_thresh_;
-    Ptr<detail::FeaturesFinder> features_finder_;
+    Ptr<Feature2D> features_finder_;
     Ptr<detail::FeaturesMatcher> features_matcher_;
     cv::UMat matching_mask_;
     Ptr<detail::BundleAdjusterBase> bundle_adjuster_;
-    /* TODO OpenCV ABI 4.x
     Ptr<detail::Estimator> estimator_;
-    */
     bool do_wave_correct_;
     detail::WaveCorrectKind wave_correct_kind_;
     Ptr<WarperCreator> warper_;
@@ -306,7 +302,7 @@ private:
     Ptr<detail::Blender> blender_;
 
     std::vector<cv::UMat> imgs_;
-    std::vector<std::vector<cv::Rect> > rois_;
+    std::vector<cv::UMat> masks_;
     std::vector<cv::Size> full_img_sizes_;
     std::vector<detail::ImageFeatures> features_;
     std::vector<detail::MatchesInfo> pairwise_matches_;
@@ -319,8 +315,15 @@ private:
     double warped_image_scale_;
 };
 
-CV_EXPORTS_W Ptr<Stitcher> createStitcher(bool try_use_gpu = false);
-CV_EXPORTS_W Ptr<Stitcher> createStitcherScans(bool try_use_gpu = false);
+/**
+ * @deprecated use Stitcher::create
+ */
+CV_DEPRECATED Ptr<Stitcher> createStitcher(bool try_use_gpu = false);
+
+/**
+ * @deprecated use Stitcher::create
+ */
+CV_DEPRECATED Ptr<Stitcher> createStitcherScans(bool try_use_gpu = false);
 
 //! @} stitching
 

modules/stitching/include/opencv2/stitching/detail/matchers.hpp

@@ -48,10 +48,6 @@
 
 #include "opencv2/opencv_modules.hpp"
 
-#ifdef HAVE_OPENCV_XFEATURES2D
-#  include "opencv2/xfeatures2d/cuda.hpp"
-#endif
-
 namespace cv {
 namespace detail {
 
@@ -67,149 +63,17 @@ struct CV_EXPORTS ImageFeatures
     UMat descriptors;
 };
 
-/** @brief Feature finders base class */
-class CV_EXPORTS FeaturesFinder
-{
-public:
-    virtual ~FeaturesFinder() {}
-    /** @overload */
-    void operator ()(InputArray image, ImageFeatures &features);
-    /** @brief Finds features in the given image.
-
-    @param image Source image
-    @param features Found features
-    @param rois Regions of interest
-
-    @sa detail::ImageFeatures, Rect_
-    */
-    void operator ()(InputArray image, ImageFeatures &features, const std::vector<cv::Rect> &rois);
-    /** @brief Finds features in the given images in parallel.
-
-    @param images Source images
-    @param features Found features for each image
-    @param rois Regions of interest for each image
-
-    @sa detail::ImageFeatures, Rect_
-    */
-    void operator ()(InputArrayOfArrays images, std::vector<ImageFeatures> &features,
-                     const std::vector<std::vector<cv::Rect> > &rois);
-    /** @overload */
-    void operator ()(InputArrayOfArrays images, std::vector<ImageFeatures> &features);
-    /** @brief Frees unused memory allocated before if there is any. */
-    virtual void collectGarbage() {}
-
-    /* TODO OpenCV ABI 4.x
-    reimplement this as public method similar to FeaturesMatcher and remove private function hack
-    @return True, if it's possible to use the same finder instance in parallel, false otherwise
-    bool isThreadSafe() const { return is_thread_safe_; }
-    */
-
-protected:
-    /** @brief This method must implement features finding logic in order to make the wrappers
-    detail::FeaturesFinder::operator()_ work.
-
-    @param image Source image
-    @param features Found features
-
-    @sa detail::ImageFeatures */
-    virtual void find(InputArray image, ImageFeatures &features) = 0;
-    /** @brief uses dynamic_cast to determine thread-safety
-    @return True, if it's possible to use the same finder instance in parallel, false otherwise
-    */
-    bool isThreadSafe() const;
-};
-
-/** @brief SURF features finder.
-
-@sa detail::FeaturesFinder, SURF
-*/
-class CV_EXPORTS SurfFeaturesFinder : public FeaturesFinder
-{
-public:
-    SurfFeaturesFinder(double hess_thresh = 300., int num_octaves = 3, int num_layers = 4,
-                       int num_octaves_descr = /*4*/3, int num_layers_descr = /*2*/4);
-
-private:
-    void find(InputArray image, ImageFeatures &features) CV_OVERRIDE;
-
-    Ptr<FeatureDetector> detector_;
-    Ptr<DescriptorExtractor> extractor_;
-    Ptr<Feature2D> surf;
-};
-
-
-/** @brief SIFT features finder.
-
-@sa detail::FeaturesFinder, SIFT
-*/
-class CV_EXPORTS SiftFeaturesFinder : public FeaturesFinder
-{
-public:
-    SiftFeaturesFinder();
-
-private:
-    void find(InputArray image, ImageFeatures &features) CV_OVERRIDE;
-    Ptr<Feature2D> sift;
-};
-
-/** @brief ORB features finder. :
-
-@sa detail::FeaturesFinder, ORB
-*/
-class CV_EXPORTS OrbFeaturesFinder : public FeaturesFinder
-{
-public:
-    OrbFeaturesFinder(Size _grid_size = Size(3,1), int nfeatures=1500, float scaleFactor=1.3f, int nlevels=5);
-
-private:
-    void find(InputArray image, ImageFeatures &features) CV_OVERRIDE;
-
-    Ptr<ORB> orb;
-    Size grid_size;
-};
-
-/** @brief AKAZE features finder. :
-
-@sa detail::FeaturesFinder, AKAZE
-*/
-class CV_EXPORTS AKAZEFeaturesFinder : public detail::FeaturesFinder
-{
-public:
-    AKAZEFeaturesFinder(AKAZE::DescriptorType descriptor_type = AKAZE::DESCRIPTOR_MLDB,
-                        int descriptor_size = 0,
-                        int descriptor_channels = 3,
-                        float threshold = 0.001f,
-                        int nOctaves = 4,
-                        int nOctaveLayers = 4,
-                        KAZE::DiffusivityType diffusivity = KAZE::DIFF_PM_G2);
-
-private:
-    void find(InputArray image, ImageFeatures &features) CV_OVERRIDE;
-
-    Ptr<AKAZE> akaze;
-};
-
-#ifdef HAVE_OPENCV_XFEATURES2D
-class CV_EXPORTS SurfFeaturesFinderGpu : public FeaturesFinder
-{
-public:
-    SurfFeaturesFinderGpu(double hess_thresh = 300., int num_octaves = 3, int num_layers = 4,
-                          int num_octaves_descr = 4, int num_layers_descr = 2);
-
-    void collectGarbage() CV_OVERRIDE;
-
-private:
-    void find(InputArray image, ImageFeatures &features) CV_OVERRIDE;
-
-    cuda::GpuMat image_;
-    cuda::GpuMat gray_image_;
-    cuda::SURF_CUDA surf_;
-    cuda::GpuMat keypoints_;
-    cuda::GpuMat descriptors_;
-    int num_octaves_, num_layers_;
-    int num_octaves_descr_, num_layers_descr_;
-};
-#endif
+CV_EXPORTS void computeImageFeatures(
+    const Ptr<Feature2D> &featuresFinder,
+    InputArrayOfArrays  images,
+    std::vector<ImageFeatures> &features,
+    InputArrayOfArrays masks = noArray());
+
+CV_EXPORTS void computeImageFeatures(
+    const Ptr<Feature2D> &featuresFinder,
+    InputArray image,
+    ImageFeatures &features,
+    InputArray mask = noArray());
 
 /** @brief Structure containing information about matches between two images.
 

modules/stitching/misc/python/pyopencv_stitching.hpp

 #ifdef HAVE_OPENCV_STITCHING
+
 typedef Stitcher::Status Status;
+typedef Stitcher::Mode Mode;
 
 #endif

modules/stitching/perf/opencl/perf_stitch.cpp

@@ -35,7 +35,7 @@ OCL_PERF_TEST_P(stitch, a123, TEST_DETECTORS)
     _imgs.push_back( imread( getDataPath("stitching/a3.png") ) );
     vector<UMat> imgs = ToUMat(_imgs);
 
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(GetParam());
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(GetParam());
     Ptr<detail::FeaturesMatcher> featuresMatcher = GetParam() == "orb"
             ? makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE)
             : makePtr<detail::BestOf2NearestMatcher>(false, SURF_MATCH_CONFIDENCE);
@@ -44,14 +44,14 @@ OCL_PERF_TEST_P(stitch, a123, TEST_DETECTORS)
 
     while(next())
     {
-        Stitcher stitcher = Stitcher::createDefault();
-        stitcher.setFeaturesFinder(featuresFinder);
-        stitcher.setFeaturesMatcher(featuresMatcher);
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setRegistrationResol(WORK_MEGAPIX);
+        Ptr<Stitcher> stitcher = Stitcher::create();
+        stitcher->setFeaturesFinder(featuresFinder);
+        stitcher->setFeaturesMatcher(featuresMatcher);
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setRegistrationResol(WORK_MEGAPIX);
 
         startTimer();
-        stitcher.stitch(imgs, pano);
+        stitcher->stitch(imgs, pano);
         stopTimer();
     }
 
@@ -69,7 +69,7 @@ OCL_PERF_TEST_P(stitch, b12, TEST_DETECTORS)
     imgs.push_back( imread( getDataPath("stitching/b1.png") ) );
     imgs.push_back( imread( getDataPath("stitching/b2.png") ) );
 
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(GetParam());
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(GetParam());
     Ptr<detail::FeaturesMatcher> featuresMatcher = GetParam() == "orb"
             ? makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE)
             : makePtr<detail::BestOf2NearestMatcher>(false, SURF_MATCH_CONFIDENCE);
@@ -78,14 +78,14 @@ OCL_PERF_TEST_P(stitch, b12, TEST_DETECTORS)
 
     while(next())
     {
-        Stitcher stitcher = Stitcher::createDefault();
-        stitcher.setFeaturesFinder(featuresFinder);
-        stitcher.setFeaturesMatcher(featuresMatcher);
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setRegistrationResol(WORK_MEGAPIX);
+        Ptr<Stitcher> stitcher = Stitcher::create();
+        stitcher->setFeaturesFinder(featuresFinder);
+        stitcher->setFeaturesMatcher(featuresMatcher);
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setRegistrationResol(WORK_MEGAPIX);
 
         startTimer();
-        stitcher.stitch(imgs, pano);
+        stitcher->stitch(imgs, pano);
         stopTimer();
     }
 
@@ -116,7 +116,7 @@ OCL_PERF_TEST_P(stitch, boat, TEST_DETECTORS)
     _imgs.push_back( imread( getDataPath("stitching/boat6.jpg") ) );
     vector<UMat> imgs = ToUMat(_imgs);
 
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(GetParam());
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(GetParam());
     Ptr<detail::FeaturesMatcher> featuresMatcher = GetParam() == "orb"
             ? makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE)
             : makePtr<detail::BestOf2NearestMatcher>(false, SURF_MATCH_CONFIDENCE);
@@ -125,14 +125,14 @@ OCL_PERF_TEST_P(stitch, boat, TEST_DETECTORS)
 
     while(next())
     {
-        Stitcher stitcher = Stitcher::createDefault();
-        stitcher.setFeaturesFinder(featuresFinder);
-        stitcher.setFeaturesMatcher(featuresMatcher);
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setRegistrationResol(WORK_MEGAPIX);
+        Ptr<Stitcher> stitcher = Stitcher::create();
+        stitcher->setFeaturesFinder(featuresFinder);
+        stitcher->setFeaturesMatcher(featuresMatcher);
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setRegistrationResol(WORK_MEGAPIX);
 
         startTimer();
-        stitcher.stitch(imgs, pano);
+        stitcher->stitch(imgs, pano);
         stopTimer();
     }
 

modules/stitching/perf/perf_estimators.cpp

@@ -28,13 +28,9 @@ PERF_TEST_P(bundleAdjuster, affine, testing::Combine(TEST_DETECTORS, AFFINE_FUNC
     string detector = get<0>(GetParam());
     string affine_fun = get<1>(GetParam());
 
-    Ptr<detail::FeaturesFinder> finder;
+    Ptr<Feature2D> finder = getFeatureFinder(detector);
     Ptr<detail::FeaturesMatcher> matcher;
     Ptr<detail::BundleAdjusterBase> bundle_adjuster;
-    if (detector == "surf")
-        finder = makePtr<detail::SurfFeaturesFinder>();
-    else if (detector == "orb")
-        finder = makePtr<detail::OrbFeaturesFinder>();
     if (affine_fun == "affinePartial")
     {
         matcher = makePtr<detail::AffineBestOf2NearestMatcher>(false);
@@ -54,7 +50,7 @@ PERF_TEST_P(bundleAdjuster, affine, testing::Combine(TEST_DETECTORS, AFFINE_FUNC
     std::vector<detail::CameraParams> cameras;
     std::vector<detail::CameraParams> cameras2;
 
-    (*finder)(images, features);
+    computeImageFeatures(finder, images, features);
     (*matcher)(features, pairwise_matches);
     if (!(*estimator)(features, pairwise_matches, cameras))
         FAIL() << "estimation failed. this should never happen.";

modules/stitching/perf/perf_matchers.cpp

@@ -29,11 +29,11 @@ PERF_TEST_P(FeaturesFinderVec, ParallelFeaturesFinder, NUMBER_IMAGES)
     vector<Mat> imgs(GetParam(), img);
     vector<detail::ImageFeatures> features(imgs.size());
 
-    Ptr<detail::FeaturesFinder> featuresFinder = makePtr<detail::OrbFeaturesFinder>();
+    Ptr<Feature2D> finder = ORB::create();
 
     TEST_CYCLE()
     {
-        (*featuresFinder)(imgs, features);
+        detail::computeImageFeatures(finder, imgs, features);
     }
 
     SANITY_CHECK_NOTHING();
@@ -45,12 +45,12 @@ PERF_TEST_P(FeaturesFinderVec, SerialFeaturesFinder, NUMBER_IMAGES)
     vector<Mat> imgs(GetParam(), img);
     vector<detail::ImageFeatures> features(imgs.size());
 
-    Ptr<detail::FeaturesFinder> featuresFinder = makePtr<detail::OrbFeaturesFinder>();
+    Ptr<Feature2D> finder = ORB::create();
 
     TEST_CYCLE()
     {
         for (size_t i = 0; i < imgs.size(); ++i)
-            (*featuresFinder)(imgs[i], features[i]);
+            detail::computeImageFeatures(finder, imgs[i], features[i]);
     }
 
     SANITY_CHECK_NOTHING();
@@ -65,16 +65,14 @@ PERF_TEST_P( match, bestOf2Nearest, TEST_DETECTORS)
     resize(img1_full, img1, Size(), scale1, scale1, INTER_LINEAR_EXACT);
     resize(img2_full, img2, Size(), scale2, scale2, INTER_LINEAR_EXACT);
 
-    Ptr<detail::FeaturesFinder> finder;
+    Ptr<Feature2D> finder = getFeatureFinder(GetParam());
     Ptr<detail::FeaturesMatcher> matcher;
     if (GetParam() == "surf")
     {
-        finder = makePtr<detail::SurfFeaturesFinder>();
         matcher = makePtr<detail::BestOf2NearestMatcher>(false, SURF_MATCH_CONFIDENCE);
     }
     else if (GetParam() == "orb")
     {
-        finder = makePtr<detail::OrbFeaturesFinder>();
         matcher = makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE);
     }
     else
@@ -83,8 +81,8 @@ PERF_TEST_P( match, bestOf2Nearest, TEST_DETECTORS)
     }
 
     detail::ImageFeatures features1, features2;
-    (*finder)(img1, features1);
-    (*finder)(img2, features2);
+    detail::computeImageFeatures(finder, img1, features1);
+    detail::computeImageFeatures(finder, img2, features2);
 
     detail::MatchesInfo pairwise_matches;
 
@@ -118,18 +116,16 @@ PERF_TEST_P( matchVector, bestOf2NearestVectorFeatures, testing::Combine(
     resize(img1_full, img1, Size(), scale1, scale1, INTER_LINEAR_EXACT);
     resize(img2_full, img2, Size(), scale2, scale2, INTER_LINEAR_EXACT);
 
-    Ptr<detail::FeaturesFinder> finder;
-    Ptr<detail::FeaturesMatcher> matcher;
     string detectorName = get<0>(GetParam());
     int featuresVectorSize = get<1>(GetParam());
+    Ptr<Feature2D> finder = getFeatureFinder(detectorName);
+    Ptr<detail::FeaturesMatcher> matcher;
     if (detectorName == "surf")
     {
-        finder = makePtr<detail::SurfFeaturesFinder>();
         matcher = makePtr<detail::BestOf2NearestMatcher>(false, SURF_MATCH_CONFIDENCE);
     }
     else if (detectorName == "orb")
     {
-        finder = makePtr<detail::OrbFeaturesFinder>();
         matcher = makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE);
     }
     else
@@ -138,8 +134,8 @@ PERF_TEST_P( matchVector, bestOf2NearestVectorFeatures, testing::Combine(
     }
 
     detail::ImageFeatures features1, features2;
-    (*finder)(img1, features1);
-    (*finder)(img2, features2);
+    detail::computeImageFeatures(finder, img1, features1);
+    detail::computeImageFeatures(finder, img2, features2);
     vector<detail::ImageFeatures> features;
     vector<detail::MatchesInfo> pairwise_matches;
     for(int i = 0; i < featuresVectorSize/2; i++)
@@ -183,16 +179,14 @@ PERF_TEST_P( match, affineBestOf2Nearest, TEST_DETECTORS)
     resize(img1_full, img1, Size(), scale1, scale1, INTER_LINEAR_EXACT);
     resize(img2_full, img2, Size(), scale2, scale2, INTER_LINEAR_EXACT);
 
-    Ptr<detail::FeaturesFinder> finder;
+    Ptr<Feature2D> finder = getFeatureFinder(GetParam());
     Ptr<detail::FeaturesMatcher> matcher;
     if (GetParam() == "surf")
     {
-        finder = makePtr<detail::SurfFeaturesFinder>();
         matcher = makePtr<detail::AffineBestOf2NearestMatcher>(false, false, SURF_MATCH_CONFIDENCE);
     }
     else if (GetParam() == "orb")
     {
-        finder = makePtr<detail::OrbFeaturesFinder>();
         matcher = makePtr<detail::AffineBestOf2NearestMatcher>(false, false, ORB_MATCH_CONFIDENCE);
     }
     else
@@ -201,8 +195,8 @@ PERF_TEST_P( match, affineBestOf2Nearest, TEST_DETECTORS)
     }
 
     detail::ImageFeatures features1, features2;
-    (*finder)(img1, features1);
-    (*finder)(img2, features2);
+    detail::computeImageFeatures(finder, img1, features1);
+    detail::computeImageFeatures(finder, img2, features2);
 
     detail::MatchesInfo pairwise_matches;
 
@@ -242,18 +236,16 @@ PERF_TEST_P( matchVector, affineBestOf2NearestVectorFeatures, testing::Combine(
     resize(img1_full, img1, Size(), scale1, scale1, INTER_LINEAR_EXACT);
     resize(img2_full, img2, Size(), scale2, scale2, INTER_LINEAR_EXACT);
 
-    Ptr<detail::FeaturesFinder> finder;
-    Ptr<detail::FeaturesMatcher> matcher;
     string detectorName = get<0>(GetParam());
     int featuresVectorSize = get<1>(GetParam());
+    Ptr<Feature2D> finder = getFeatureFinder(detectorName);
+    Ptr<detail::FeaturesMatcher> matcher;
     if (detectorName == "surf")
     {
-        finder = makePtr<detail::SurfFeaturesFinder>();
         matcher = makePtr<detail::AffineBestOf2NearestMatcher>(false, false, SURF_MATCH_CONFIDENCE);
     }
     else if (detectorName == "orb")
     {
-        finder = makePtr<detail::OrbFeaturesFinder>();
         matcher = makePtr<detail::AffineBestOf2NearestMatcher>(false, false, ORB_MATCH_CONFIDENCE);
     }
     else
@@ -262,8 +254,8 @@ PERF_TEST_P( matchVector, affineBestOf2NearestVectorFeatures, testing::Combine(
     }
 
     detail::ImageFeatures features1, features2;
-    (*finder)(img1, features1);
-    (*finder)(img2, features2);
+    detail::computeImageFeatures(finder, img1, features1);
+    detail::computeImageFeatures(finder, img2, features2);
     vector<detail::ImageFeatures> features;
     vector<detail::MatchesInfo> pairwise_matches;
     for(int i = 0; i < featuresVectorSize/2; i++)
@@ -288,12 +280,12 @@ PERF_TEST_P( matchVector, affineBestOf2NearestVectorFeatures, testing::Combine(
         if (pairwise_matches[i].src_img_idx < 0)
             continue;
 
-        EXPECT_TRUE(pairwise_matches[i].matches.size() > 400);
+        EXPECT_GT(pairwise_matches[i].matches.size(), 200u);
         EXPECT_FALSE(pairwise_matches[i].H.empty());
         ++matches_count;
     }
 
-    EXPECT_TRUE(matches_count > 0);
+    EXPECT_GT(matches_count, 0u);
 
     SANITY_CHECK_NOTHING();
 }

modules/stitching/perf/perf_precomp.hpp

@@ -4,19 +4,25 @@
 #include "opencv2/ts.hpp"
 #include "opencv2/stitching.hpp"
 
+#ifdef HAVE_OPENCV_XFEATURES2D
+#include "opencv2/xfeatures2d/nonfree.hpp"
+#endif
+
 namespace cv
 {
 
-static inline Ptr<detail::FeaturesFinder> getFeatureFinder(const std::string& name)
+static inline Ptr<Feature2D> getFeatureFinder(const std::string& name)
 {
     if (name == "orb")
-        return makePtr<detail::OrbFeaturesFinder>();
+        return ORB::create();
+#ifdef HAVE_OPENCV_XFEATURES2D
     else if (name == "surf")
-        return makePtr<detail::SurfFeaturesFinder>();
+        return xfeatures2d::SURF::create();
+#endif
     else if (name == "akaze")
-        return makePtr<detail::AKAZEFeaturesFinder>();
+        return AKAZE::create();
     else
-        return Ptr<detail::FeaturesFinder>();
+        return Ptr<Feature2D>();
 }
 
 } // namespace cv

modules/stitching/perf/perf_stich.cpp

@@ -31,7 +31,7 @@ PERF_TEST_P(stitch, a123, TEST_DETECTORS)
     imgs.push_back( imread( getDataPath("stitching/a2.png") ) );
     imgs.push_back( imread( getDataPath("stitching/a3.png") ) );
 
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(GetParam());
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(GetParam());
 
     Ptr<detail::FeaturesMatcher> featuresMatcher = GetParam() == "orb"
             ? makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE)
@@ -41,14 +41,14 @@ PERF_TEST_P(stitch, a123, TEST_DETECTORS)
 
     while(next())
     {
-        Stitcher stitcher = Stitcher::createDefault();
-        stitcher.setFeaturesFinder(featuresFinder);
-        stitcher.setFeaturesMatcher(featuresMatcher);
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setRegistrationResol(WORK_MEGAPIX);
+        Ptr<Stitcher> stitcher = Stitcher::create();
+        stitcher->setFeaturesFinder(featuresFinder);
+        stitcher->setFeaturesMatcher(featuresMatcher);
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setRegistrationResol(WORK_MEGAPIX);
 
         startTimer();
-        stitcher.stitch(imgs, pano);
+        stitcher->stitch(imgs, pano);
         stopTimer();
     }
 
@@ -66,7 +66,7 @@ PERF_TEST_P(stitch, b12, TEST_DETECTORS)
     imgs.push_back( imread( getDataPath("stitching/b1.png") ) );
     imgs.push_back( imread( getDataPath("stitching/b2.png") ) );
 
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(GetParam());
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(GetParam());
 
     Ptr<detail::FeaturesMatcher> featuresMatcher = GetParam() == "orb"
             ? makePtr<detail::BestOf2NearestMatcher>(false, ORB_MATCH_CONFIDENCE)
@@ -76,14 +76,14 @@ PERF_TEST_P(stitch, b12, TEST_DETECTORS)
 
     while(next())
     {
-        Stitcher stitcher = Stitcher::createDefault();
-        stitcher.setFeaturesFinder(featuresFinder);
-        stitcher.setFeaturesMatcher(featuresMatcher);
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setRegistrationResol(WORK_MEGAPIX);
+        Ptr<Stitcher> stitcher = Stitcher::create();
+        stitcher->setFeaturesFinder(featuresFinder);
+        stitcher->setFeaturesMatcher(featuresMatcher);
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setRegistrationResol(WORK_MEGAPIX);
 
         startTimer();
-        stitcher.stitch(imgs, pano);
+        stitcher->stitch(imgs, pano);
         stopTimer();
     }
 
@@ -101,7 +101,7 @@ PERF_TEST_P(stitchDatasets, affine, testing::Combine(AFFINE_DATASETS, TEST_DETEC
     Mat pano;
     vector<Mat> imgs;
     int width, height, allowed_diff = 20;
-    Ptr<detail::FeaturesFinder> featuresFinder = getFeatureFinder(detector);
+    Ptr<Feature2D> featuresFinder = getFeatureFinder(detector);
 
     if(dataset == "budapest")
     {
@@ -116,6 +116,10 @@ PERF_TEST_P(stitchDatasets, affine, testing::Combine(AFFINE_DATASETS, TEST_DETEC
         // this dataset is big, the results between surf and orb differ slightly,
         // but both are still good
         allowed_diff = 50;
+        // we need to boost ORB number of features to be able to stitch this dataset
+        // SURF works just fine with default settings
+        if(detector == "orb")
+            featuresFinder = ORB::create(1500);
     }
     else if (dataset == "newspaper")
     {
@@ -128,7 +132,7 @@ PERF_TEST_P(stitchDatasets, affine, testing::Combine(AFFINE_DATASETS, TEST_DETEC
         // we need to boost ORB number of features to be able to stitch this dataset
         // SURF works just fine with default settings
         if(detector == "orb")
-            featuresFinder = makePtr<detail::OrbFeaturesFinder>(Size(3,1), 3000);
+            featuresFinder = ORB::create(3000);
     }
     else if (dataset == "prague")
     {
@@ -149,7 +153,7 @@ PERF_TEST_P(stitchDatasets, affine, testing::Combine(AFFINE_DATASETS, TEST_DETEC
 
     while(next())
     {
-        Ptr<Stitcher> stitcher = Stitcher::create(Stitcher::SCANS, false);
+        Ptr<Stitcher> stitcher = Stitcher::create(Stitcher::SCANS);
         stitcher->setFeaturesFinder(featuresFinder);
 
         if (cv::ocl::useOpenCL())

modules/stitching/src/matchers.cpp

@@ -48,16 +48,6 @@ using namespace cv;
 using namespace cv::detail;
 using namespace cv::cuda;
 
-#ifdef HAVE_OPENCV_XFEATURES2D
-#include "opencv2/xfeatures2d.hpp"
-using xfeatures2d::SURF;
-using xfeatures2d::SIFT;
-#else
-#  if defined(_MSC_VER)
-#    pragma warning(disable:4702)  // unreachable code
-#  endif
-#endif
-
 #ifdef HAVE_OPENCV_CUDAIMGPROC
 #  include "opencv2/cudaimgproc.hpp"
 #endif
@@ -121,35 +111,6 @@ private:
 };
 
 
-struct FindFeaturesBody : ParallelLoopBody
-{
-    FindFeaturesBody(FeaturesFinder &finder, InputArrayOfArrays images,
-                     std::vector<ImageFeatures> &features, const std::vector<std::vector<cv::Rect> > *rois)
-            : finder_(finder), images_(images), features_(features), rois_(rois) {}
-
-    void operator ()(const Range &r) const CV_OVERRIDE
-    {
-        for (int i = r.start; i < r.end; ++i)
-        {
-            Mat image = images_.getMat(i);
-            if (rois_)
-                finder_(image, features_[i], (*rois_)[i]);
-            else
-                finder_(image, features_[i]);
-        }
-    }
-
-private:
-    FeaturesFinder &finder_;
-    InputArrayOfArrays images_;
-    std::vector<ImageFeatures> &features_;
-    const std::vector<std::vector<cv::Rect> > *rois_;
-
-    // to cease visual studio warning
-    void operator =(const FindFeaturesBody&);
-};
-
-
 //////////////////////////////////////////////////////////////////////////////
 
 typedef std::set<std::pair<int,int> > MatchesSet;
@@ -318,339 +279,40 @@ void GpuMatcher::collectGarbage()
 namespace cv {
 namespace detail {
 
-void FeaturesFinder::operator ()(InputArray  image, ImageFeatures &features)
+void computeImageFeatures(
+    const Ptr<Feature2D> &featuresFinder,
+    InputArrayOfArrays  images,
+    std::vector<ImageFeatures> &features,
+    InputArrayOfArrays masks)
 {
-    find(image, features);
-    features.img_size = image.size();
-}
-
+    // compute all features
+    std::vector<std::vector<KeyPoint>> keypoints;
+    std::vector<UMat> descriptors;
+    // TODO replace with 1 call to new over load of detectAndCompute
+    featuresFinder->detect(images, keypoints, masks);
+    featuresFinder->compute(images, keypoints, descriptors);
 
-void FeaturesFinder::operator ()(InputArray image, ImageFeatures &features, const std::vector<Rect> &rois)
-{
-    std::vector<ImageFeatures> roi_features(rois.size());
-    size_t total_kps_count = 0;
-    int total_descriptors_height = 0;
-
-    for (size_t i = 0; i < rois.size(); ++i)
-    {
-        find(image.getUMat()(rois[i]), roi_features[i]);
-        total_kps_count += roi_features[i].keypoints.size();
-        total_descriptors_height += roi_features[i].descriptors.rows;
-    }
-
-    features.img_size = image.size();
-    features.keypoints.resize(total_kps_count);
-    features.descriptors.create(total_descriptors_height,
-                                roi_features[0].descriptors.cols,
-                                roi_features[0].descriptors.type());
-
-    int kp_idx = 0;
-    int descr_offset = 0;
-    for (size_t i = 0; i < rois.size(); ++i)
-    {
-        for (size_t j = 0; j < roi_features[i].keypoints.size(); ++j, ++kp_idx)
-        {
-            features.keypoints[kp_idx] = roi_features[i].keypoints[j];
-            features.keypoints[kp_idx].pt.x += (float)rois[i].x;
-            features.keypoints[kp_idx].pt.y += (float)rois[i].y;
-        }
-        UMat subdescr = features.descriptors.rowRange(
-                descr_offset, descr_offset + roi_features[i].descriptors.rows);
-        roi_features[i].descriptors.copyTo(subdescr);
-        descr_offset += roi_features[i].descriptors.rows;
-    }
-}
-
-
-void FeaturesFinder::operator ()(InputArrayOfArrays images, std::vector<ImageFeatures> &features)
-{
+    // store to ImageFeatures
     size_t count = images.total();
     features.resize(count);
-
-    FindFeaturesBody body(*this, images, features, NULL);
-    if (isThreadSafe())
-        parallel_for_(Range(0, static_cast<int>(count)), body);
-    else
-        body(Range(0, static_cast<int>(count)));
-}
-
-
-void FeaturesFinder::operator ()(InputArrayOfArrays images, std::vector<ImageFeatures> &features,
-                                  const std::vector<std::vector<cv::Rect> > &rois)
-{
-    CV_Assert(rois.size() == images.total());
-    size_t count = images.total();
-    features.resize(count);
-
-    FindFeaturesBody body(*this, images, features, &rois);
-    if (isThreadSafe())
-        parallel_for_(Range(0, static_cast<int>(count)), body);
-    else
-        body(Range(0, static_cast<int>(count)));
-}
-
-
-bool FeaturesFinder::isThreadSafe() const
-{
-#ifdef HAVE_OPENCL
-    if (ocl::isOpenCLActivated())
-    {
-        return false;
-    }
-#endif
-    if (dynamic_cast<const SurfFeaturesFinder*>(this))
-    {
-        return true;
-    }
-    else if (dynamic_cast<const OrbFeaturesFinder*>(this))
-    {
-        return true;
-    }
-    else
-    {
-        return false;
-    }
-}
-
-
-SurfFeaturesFinder::SurfFeaturesFinder(double hess_thresh, int num_octaves, int num_layers,
-                                       int num_octaves_descr, int num_layers_descr)
-{
-#ifdef HAVE_OPENCV_XFEATURES2D
-    if (num_octaves_descr == num_octaves && num_layers_descr == num_layers)
-    {
-        Ptr<SURF> surf_ = SURF::create();
-        if( !surf_ )
-            CV_Error( Error::StsNotImplemented, "OpenCV was built without SURF support" );
-        surf_->setHessianThreshold(hess_thresh);
-        surf_->setNOctaves(num_octaves);
-        surf_->setNOctaveLayers(num_layers);
-        surf = surf_;
-    }
-    else
-    {
-        Ptr<SURF> sdetector_ = SURF::create();
-        Ptr<SURF> sextractor_ = SURF::create();
-
-        if( !sdetector_ || !sextractor_ )
-            CV_Error( Error::StsNotImplemented, "OpenCV was built without SURF support" );
-
-        sdetector_->setHessianThreshold(hess_thresh);
-        sdetector_->setNOctaves(num_octaves);
-        sdetector_->setNOctaveLayers(num_layers);
-
-        sextractor_->setNOctaves(num_octaves_descr);
-        sextractor_->setNOctaveLayers(num_layers_descr);
-
-        detector_ = sdetector_;
-        extractor_ = sextractor_;
-    }
-#else
-    CV_UNUSED(hess_thresh);
-    CV_UNUSED(num_octaves);
-    CV_UNUSED(num_layers);
-    CV_UNUSED(num_octaves_descr);
-    CV_UNUSED(num_layers_descr);
-    CV_Error( Error::StsNotImplemented, "OpenCV was built without SURF support" );
-#endif
-}
-
-void SurfFeaturesFinder::find(InputArray image, ImageFeatures &features)
-{
-    UMat gray_image;
-    CV_Assert((image.type() == CV_8UC3) || (image.type() == CV_8UC1));
-    if(image.type() == CV_8UC3)
-    {
-        cvtColor(image, gray_image, COLOR_BGR2GRAY);
-    }
-    else
-    {
-        gray_image = image.getUMat();
-    }
-    if (!surf)
+    CV_Assert(count == keypoints.size() && count == descriptors.size());
+    for (size_t i = 0; i < count; ++i)
     {
-        detector_->detect(gray_image, features.keypoints);
-        extractor_->compute(gray_image, features.keypoints, features.descriptors);
-    }
-    else
-    {
-        UMat descriptors;
-        surf->detectAndCompute(gray_image, Mat(), features.keypoints, descriptors);
-        features.descriptors = descriptors.reshape(1, (int)features.keypoints.size());
+        features[i].img_size = images.size(int(i));
+        features[i].keypoints = std::move(keypoints[i]);
+        features[i].descriptors = std::move(descriptors[i]);
     }
 }
 
-SiftFeaturesFinder::SiftFeaturesFinder()
+void computeImageFeatures(
+    const Ptr<Feature2D> &featuresFinder,
+    InputArray image,
+    ImageFeatures &features,
+    InputArray mask)
 {
-#ifdef HAVE_OPENCV_XFEATURES2D
-    Ptr<SIFT> sift_ = SIFT::create();
-    if( !sift_ )
-        CV_Error( Error::StsNotImplemented, "OpenCV was built without SIFT support" );
-    sift = sift_;
-#else
-    CV_Error( Error::StsNotImplemented, "OpenCV was built without SIFT support" );
-#endif
-}
-
-void SiftFeaturesFinder::find(InputArray image, ImageFeatures &features)
-{
-    UMat gray_image;
-    CV_Assert((image.type() == CV_8UC3) || (image.type() == CV_8UC1));
-    if(image.type() == CV_8UC3)
-    {
-        cvtColor(image, gray_image, COLOR_BGR2GRAY);
-    }
-    else
-    {
-        gray_image = image.getUMat();
-    }
-    UMat descriptors;
-    sift->detectAndCompute(gray_image, Mat(), features.keypoints, descriptors);
-    features.descriptors = descriptors.reshape(1, (int)features.keypoints.size());
-}
-
-OrbFeaturesFinder::OrbFeaturesFinder(Size _grid_size, int n_features, float scaleFactor, int nlevels)
-{
-    grid_size = _grid_size;
-    orb = ORB::create(n_features * (99 + grid_size.area())/100/grid_size.area(), scaleFactor, nlevels);
-}
-
-void OrbFeaturesFinder::find(InputArray image, ImageFeatures &features)
-{
-    UMat gray_image;
-
-    CV_Assert((image.type() == CV_8UC3) || (image.type() == CV_8UC4) || (image.type() == CV_8UC1));
-
-    if (image.type() == CV_8UC3) {
-        cvtColor(image, gray_image, COLOR_BGR2GRAY);
-    } else if (image.type() == CV_8UC4) {
-        cvtColor(image, gray_image, COLOR_BGRA2GRAY);
-    } else if (image.type() == CV_8UC1) {
-        gray_image = image.getUMat();
-    } else {
-        CV_Error(Error::StsUnsupportedFormat, "");
-    }
-
-    if (grid_size.area() == 1)
-        orb->detectAndCompute(gray_image, Mat(), features.keypoints, features.descriptors);
-    else
-    {
-        features.keypoints.clear();
-        features.descriptors.release();
-
-        std::vector<KeyPoint> points;
-        Mat _descriptors;
-        UMat descriptors;
-
-        for (int r = 0; r < grid_size.height; ++r)
-            for (int c = 0; c < grid_size.width; ++c)
-            {
-                int xl = c * gray_image.cols / grid_size.width;
-                int yl = r * gray_image.rows / grid_size.height;
-                int xr = (c+1) * gray_image.cols / grid_size.width;
-                int yr = (r+1) * gray_image.rows / grid_size.height;
-
-                // LOGLN("OrbFeaturesFinder::find: gray_image.empty=" << (gray_image.empty()?"true":"false") << ", "
-                //     << " gray_image.size()=(" << gray_image.size().width << "x" << gray_image.size().height << "), "
-                //     << " yl=" << yl << ", yr=" << yr << ", "
-                //     << " xl=" << xl << ", xr=" << xr << ", gray_image.data=" << ((size_t)gray_image.data) << ", "
-                //     << "gray_image.dims=" << gray_image.dims << "\n");
-
-                UMat gray_image_part=gray_image(Range(yl, yr), Range(xl, xr));
-                // LOGLN("OrbFeaturesFinder::find: gray_image_part.empty=" << (gray_image_part.empty()?"true":"false") << ", "
-                //     << " gray_image_part.size()=(" << gray_image_part.size().width << "x" << gray_image_part.size().height << "), "
-                //     << " gray_image_part.dims=" << gray_image_part.dims << ", "
-                //     << " gray_image_part.data=" << ((size_t)gray_image_part.data) << "\n");
-
-                orb->detectAndCompute(gray_image_part, UMat(), points, descriptors);
-
-                features.keypoints.reserve(features.keypoints.size() + points.size());
-                for (std::vector<KeyPoint>::iterator kp = points.begin(); kp != points.end(); ++kp)
-                {
-                    kp->pt.x += xl;
-                    kp->pt.y += yl;
-                    features.keypoints.push_back(*kp);
-                }
-                _descriptors.push_back(descriptors.getMat(ACCESS_READ));
-            }
-
-        // TODO optimize copyTo()
-        //features.descriptors = _descriptors.getUMat(ACCESS_READ);
-        _descriptors.copyTo(features.descriptors);
-    }
-}
-
-AKAZEFeaturesFinder::AKAZEFeaturesFinder(AKAZE::DescriptorType descriptor_type,
-                                         int descriptor_size,
-                                         int descriptor_channels,
-                                         float threshold,
-                                         int nOctaves,
-                                         int nOctaveLayers,
-                                         KAZE::DiffusivityType diffusivity)
-{
-    akaze = AKAZE::create(descriptor_type, descriptor_size, descriptor_channels,
-                          threshold, nOctaves, nOctaveLayers, diffusivity);
-}
-
-void AKAZEFeaturesFinder::find(InputArray image, detail::ImageFeatures &features)
-{
-    CV_Assert((image.type() == CV_8UC3) || (image.type() == CV_8UC1));
-    akaze->detectAndCompute(image, noArray(), features.keypoints, features.descriptors);
-}
-
-#ifdef HAVE_OPENCV_XFEATURES2D
-SurfFeaturesFinderGpu::SurfFeaturesFinderGpu(double hess_thresh, int num_octaves, int num_layers,
-                                             int num_octaves_descr, int num_layers_descr)
-{
-    surf_.keypointsRatio = 0.1f;
-    surf_.hessianThreshold = hess_thresh;
-    surf_.extended = false;
-    num_octaves_ = num_octaves;
-    num_layers_ = num_layers;
-    num_octaves_descr_ = num_octaves_descr;
-    num_layers_descr_ = num_layers_descr;
-}
-
-
-void SurfFeaturesFinderGpu::find(InputArray image, ImageFeatures &features)
-{
-    CV_Assert(image.depth() == CV_8U);
-
-    ensureSizeIsEnough(image.size(), image.type(), image_);
-    image_.upload(image);
-
-    ensureSizeIsEnough(image.size(), CV_8UC1, gray_image_);
-
-#ifdef HAVE_OPENCV_CUDAIMGPROC
-    cv::cuda::cvtColor(image_, gray_image_, COLOR_BGR2GRAY);
-#else
-    cvtColor(image_, gray_image_, COLOR_BGR2GRAY);
-#endif
-
-    surf_.nOctaves = num_octaves_;
-    surf_.nOctaveLayers = num_layers_;
-    surf_.upright = false;
-    surf_(gray_image_, GpuMat(), keypoints_);
-
-    surf_.nOctaves = num_octaves_descr_;
-    surf_.nOctaveLayers = num_layers_descr_;
-    surf_.upright = true;
-    surf_(gray_image_, GpuMat(), keypoints_, descriptors_, true);
-    surf_.downloadKeypoints(keypoints_, features.keypoints);
-
-    descriptors_.download(features.descriptors);
-}
-
-void SurfFeaturesFinderGpu::collectGarbage()
-{
-    surf_.releaseMemory();
-    image_.release();
-    gray_image_.release();
-    keypoints_.release();
-    descriptors_.release();
+    features.img_size = image.size();
+    featuresFinder->detectAndCompute(image, mask, features.keypoints, features.descriptors);
 }
-#endif
-
 
 //////////////////////////////////////////////////////////////////////////////
 

modules/stitching/src/precomp.hpp

@@ -87,10 +87,6 @@
 #  include "opencv2/cudalegacy.hpp"
 #endif
 
-#ifdef HAVE_OPENCV_XFEATURES2D
-#  include "opencv2/xfeatures2d/cuda.hpp"
-#endif
-
 #include "opencv2/core/private.hpp"
 
 #include "util_log.hpp"

modules/stitching/src/stitcher.cpp

@@ -44,67 +44,40 @@
 
 namespace cv {
 
-Stitcher Stitcher::createDefault(bool try_use_gpu)
+Ptr<Stitcher> Stitcher::create(Mode mode)
 {
-    Stitcher stitcher;
-    stitcher.setRegistrationResol(0.6);
-    stitcher.setSeamEstimationResol(0.1);
-    stitcher.setCompositingResol(ORIG_RESOL);
-    stitcher.setPanoConfidenceThresh(1);
-    stitcher.setWaveCorrection(true);
-    stitcher.setWaveCorrectKind(detail::WAVE_CORRECT_HORIZ);
-    stitcher.setFeaturesMatcher(makePtr<detail::BestOf2NearestMatcher>(try_use_gpu));
-    stitcher.setBundleAdjuster(makePtr<detail::BundleAdjusterRay>());
-
-#ifdef HAVE_OPENCV_CUDALEGACY
-    if (try_use_gpu && cuda::getCudaEnabledDeviceCount() > 0)
-    {
-#ifdef HAVE_OPENCV_XFEATURES2D
-        stitcher.setFeaturesFinder(makePtr<detail::SurfFeaturesFinderGpu>());
-#else
-        stitcher.setFeaturesFinder(makePtr<detail::OrbFeaturesFinder>());
-#endif
-        stitcher.setWarper(makePtr<SphericalWarperGpu>());
-        stitcher.setSeamFinder(makePtr<detail::GraphCutSeamFinderGpu>());
-    }
-    else
-#endif
-    {
-#ifdef HAVE_OPENCV_XFEATURES2D
-        stitcher.setFeaturesFinder(makePtr<detail::SurfFeaturesFinder>());
-#else
-        stitcher.setFeaturesFinder(makePtr<detail::OrbFeaturesFinder>());
-#endif
-        stitcher.setWarper(makePtr<SphericalWarper>());
-        stitcher.setSeamFinder(makePtr<detail::GraphCutSeamFinder>(detail::GraphCutSeamFinderBase::COST_COLOR));
-    }
+    Ptr<Stitcher> stitcher = makePtr<Stitcher>();
 
-    stitcher.setExposureCompensator(makePtr<detail::BlocksGainCompensator>());
-    stitcher.setBlender(makePtr<detail::MultiBandBlender>(try_use_gpu));
+    stitcher->setRegistrationResol(0.6);
+    stitcher->setSeamEstimationResol(0.1);
+    stitcher->setCompositingResol(ORIG_RESOL);
+    stitcher->setPanoConfidenceThresh(1);
+    stitcher->setSeamFinder(makePtr<detail::GraphCutSeamFinder>(detail::GraphCutSeamFinderBase::COST_COLOR));
+    stitcher->setBlender(makePtr<detail::MultiBandBlender>(false));
+    stitcher->setFeaturesFinder(ORB::create());
 
-    stitcher.work_scale_ = 1;
-    stitcher.seam_scale_ = 1;
-    stitcher.seam_work_aspect_ = 1;
-    stitcher.warped_image_scale_ = 1;
-
-    return stitcher;
-}
-
-
-Ptr<Stitcher> Stitcher::create(Mode mode, bool try_use_gpu)
-{
-    Stitcher stit = createDefault(try_use_gpu);
-    Ptr<Stitcher> stitcher = makePtr<Stitcher>(stit);
+    stitcher->work_scale_ = 1;
+    stitcher->seam_scale_ = 1;
+    stitcher->seam_work_aspect_ = 1;
+    stitcher->warped_image_scale_ = 1;
 
     switch (mode)
     {
     case PANORAMA: // PANORAMA is the default
-        // already setup
+        // mostly already setup
+        stitcher->setEstimator(makePtr<detail::HomographyBasedEstimator>());
+        stitcher->setWaveCorrection(true);
+        stitcher->setWaveCorrectKind(detail::WAVE_CORRECT_HORIZ);
+        stitcher->setFeaturesMatcher(makePtr<detail::BestOf2NearestMatcher>(false));
+        stitcher->setBundleAdjuster(makePtr<detail::BundleAdjusterRay>());
+        stitcher->setWarper(makePtr<SphericalWarper>());
+        stitcher->setExposureCompensator(makePtr<detail::BlocksGainCompensator>());
     break;
 
     case SCANS:
+        stitcher->setEstimator(makePtr<detail::AffineBasedEstimator>());
         stitcher->setWaveCorrection(false);
-        stitcher->setFeaturesMatcher(makePtr<detail::AffineBestOf2NearestMatcher>(false, try_use_gpu));
+        stitcher->setFeaturesMatcher(makePtr<detail::AffineBestOf2NearestMatcher>(false, false));
         stitcher->setBundleAdjuster(makePtr<detail::BundleAdjusterAffinePartial>());
         stitcher->setWarper(makePtr<AffineWarper>());
         stitcher->setExposureCompensator(makePtr<detail::NoExposureCompensator>());
@@ -119,20 +92,12 @@ Ptr<Stitcher> Stitcher::create(Mode mode, bool try_use_gpu)
 }
 
 
-Stitcher::Status Stitcher::estimateTransform(InputArrayOfArrays images)
-{
-    CV_INSTRUMENT_REGION();
-
-    return estimateTransform(images, std::vector<std::vector<Rect> >());
-}
-
-
-Stitcher::Status Stitcher::estimateTransform(InputArrayOfArrays images, const std::vector<std::vector<Rect> > &rois)
+Stitcher::Status Stitcher::estimateTransform(InputArrayOfArrays images, InputArrayOfArrays masks)
 {
     CV_INSTRUMENT_REGION();
 
     images.getUMatVector(imgs_);
-    rois_ = rois;
+    masks.getUMatVector(masks_);
 
     Status status;
 
@@ -407,20 +372,15 @@ Stitcher::Status Stitcher::composePanorama(InputArrayOfArrays images, OutputArra
 
 Stitcher::Status Stitcher::stitch(InputArrayOfArrays images, OutputArray pano)
 {
-    CV_INSTRUMENT_REGION();
-
-    Status status = estimateTransform(images);
-    if (status != OK)
-        return status;
-    return composePanorama(pano);
+    return stitch(images, noArray(), pano);
 }
 
 
-Stitcher::Status Stitcher::stitch(InputArrayOfArrays images, const std::vector<std::vector<Rect> > &rois, OutputArray pano)
+Stitcher::Status Stitcher::stitch(InputArrayOfArrays images, InputArrayOfArrays masks, OutputArray pano)
 {
     CV_INSTRUMENT_REGION();
 
-    Status status = estimateTransform(images, rois);
+    Status status = estimateTransform(images, masks);
     if (status != OK)
         return status;
     return composePanorama(pano);
@@ -440,7 +400,6 @@ Stitcher::Status Stitcher::matchImages()
     seam_scale_ = 1;
     bool is_work_scale_set = false;
     bool is_seam_scale_set = false;
-    UMat full_img, img;
     features_.resize(imgs_.size());
     seam_est_imgs_.resize(imgs_.size());
     full_img_sizes_.resize(imgs_.size());
@@ -451,16 +410,14 @@ Stitcher::Status Stitcher::matchImages()
 #endif
 
     std::vector<UMat> feature_find_imgs(imgs_.size());
-    std::vector<std::vector<Rect> > feature_find_rois(rois_.size());
+    std::vector<UMat> feature_find_masks(masks_.size());
 
     for (size_t i = 0; i < imgs_.size(); ++i)
     {
-        full_img = imgs_[i];
-        full_img_sizes_[i] = full_img.size();
-
+        full_img_sizes_[i] = imgs_[i].size();
         if (registr_resol_ < 0)
         {
-            img = full_img;
+            feature_find_imgs[i] = imgs_[i];
             work_scale_ = 1;
             is_work_scale_set = true;
         }
@@ -468,50 +425,34 @@ Stitcher::Status Stitcher::matchImages()
         {
             if (!is_work_scale_set)
             {
-                work_scale_ = std::min(1.0, std::sqrt(registr_resol_ * 1e6 / full_img.size().area()));
+                work_scale_ = std::min(1.0, std::sqrt(registr_resol_ * 1e6 / full_img_sizes_[i].area()));
                 is_work_scale_set = true;
             }
-            resize(full_img, img, Size(), work_scale_, work_scale_, INTER_LINEAR_EXACT);
+            resize(imgs_[i], feature_find_imgs[i], Size(), work_scale_, work_scale_, INTER_LINEAR_EXACT);
         }
         if (!is_seam_scale_set)
         {
-            seam_scale_ = std::min(1.0, std::sqrt(seam_est_resol_ * 1e6 / full_img.size().area()));
+            seam_scale_ = std::min(1.0, std::sqrt(seam_est_resol_ * 1e6 / full_img_sizes_[i].area()));
             seam_work_aspect_ = seam_scale_ / work_scale_;
             is_seam_scale_set = true;
         }
 
-        if (rois_.empty())
-            feature_find_imgs[i] = img;
-        else
-        {
-            feature_find_rois[i].resize(rois_[i].size());
-            for (size_t j = 0; j < rois_[i].size(); ++j)
+        if (!masks_.empty())
         {
-                Point tl(cvRound(rois_[i][j].x * work_scale_), cvRound(rois_[i][j].y * work_scale_));
-                Point br(cvRound(rois_[i][j].br().x * work_scale_), cvRound(rois_[i][j].br().y * work_scale_));
-                feature_find_rois[i][j] = Rect(tl, br);
-            }
-            feature_find_imgs[i] = img;
+            resize(masks_[i], feature_find_masks[i], Size(), work_scale_, work_scale_, INTER_NEAREST);
         }
         features_[i].img_idx = (int)i;
         LOGLN("Features in image #" << i+1 << ": " << features_[i].keypoints.size());
 
-        resize(full_img, img, Size(), seam_scale_, seam_scale_, INTER_LINEAR_EXACT);
-        seam_est_imgs_[i] = img.clone();
+        resize(imgs_[i], seam_est_imgs_[i], Size(), seam_scale_, seam_scale_, INTER_LINEAR_EXACT);
     }
 
     // find features possibly in parallel
-    if (rois_.empty())
-        (*features_finder_)(feature_find_imgs, features_);
-    else
-        (*features_finder_)(feature_find_imgs, features_, feature_find_rois);
+    detail::computeImageFeatures(features_finder_, feature_find_imgs, features_, feature_find_masks);
 
     // Do it to save memory
-    features_finder_->collectGarbage();
-    full_img.release();
-    img.release();
     feature_find_imgs.clear();
-    feature_find_rois.clear();
+    feature_find_masks.clear();
 
     LOGLN("Finding features, time: " << ((getTickCount() - t) / getTickFrequency()) << " sec");
 
@@ -550,16 +491,8 @@ Stitcher::Status Stitcher::matchImages()
 
 Stitcher::Status Stitcher::estimateCameraParams()
 {
-    /* TODO OpenCV ABI 4.x
-    get rid of this dynamic_cast hack and use estimator_
-    */
-    Ptr<detail::Estimator> estimator;
-    if (dynamic_cast<detail::AffineBestOf2NearestMatcher*>(features_matcher_.get()))
-        estimator = makePtr<detail::AffineBasedEstimator>();
-    else
-        estimator = makePtr<detail::HomographyBasedEstimator>();
-
-    if (!(*estimator)(features_, pairwise_matches_, cameras_))
+    // estimate homography in global frame
+    if (!(*estimator_)(features_, pairwise_matches_, cameras_))
         return ERR_HOMOGRAPHY_EST_FAIL;
 
     for (size_t i = 0; i < cameras_.size(); ++i)
@@ -602,17 +535,17 @@ Stitcher::Status Stitcher::estimateCameraParams()
 }
 
 
-Ptr<Stitcher> createStitcher(bool try_use_gpu)
+CV_DEPRECATED Ptr<Stitcher> createStitcher(bool /*ignored*/)
 {
     CV_INSTRUMENT_REGION();
 
-    return Stitcher::create(Stitcher::PANORAMA, try_use_gpu);
+    return Stitcher::create(Stitcher::PANORAMA);
 }
 
-Ptr<Stitcher> createStitcherScans(bool try_use_gpu)
+CV_DEPRECATED Ptr<Stitcher> createStitcherScans(bool /*ignored*/)
 {
     CV_INSTRUMENT_REGION();
 
-    return Stitcher::create(Stitcher::SCANS, try_use_gpu);
+    return Stitcher::create(Stitcher::SCANS);
 }
 } // namespace cv

modules/stitching/test/test_matchers.cpp

@@ -48,54 +48,61 @@ namespace opencv_test { namespace {
 
 TEST(SurfFeaturesFinder, CanFindInROIs)
 {
-    Ptr<detail::FeaturesFinder> finder = makePtr<detail::SurfFeaturesFinder>();
+    Ptr<Feature2D> finder = xfeatures2d::SURF::create();
     Mat img  = imread(string(cvtest::TS::ptr()->get_data_path()) + "cv/shared/lena.png");
 
     vector<Rect> rois;
     rois.push_back(Rect(0, 0, img.cols / 2, img.rows / 2));
     rois.push_back(Rect(img.cols / 2, img.rows / 2, img.cols - img.cols / 2, img.rows - img.rows / 2));
+
+    // construct mask
+    Mat mask = Mat::zeros(img.size(), CV_8U);
+    for (const Rect &roi : rois)
+    {
+        Mat(mask, roi) = 1;
+    }
+
     detail::ImageFeatures roi_features;
-    (*finder)(img, roi_features, rois);
+    detail::computeImageFeatures(finder, img, roi_features, mask);
 
     int tl_rect_count = 0, br_rect_count = 0, bad_count = 0;
-    for (size_t i = 0; i < roi_features.keypoints.size(); ++i)
+    for (const auto &keypoint : roi_features.keypoints)
     {
-        Point2f pt = roi_features.keypoints[i].pt;
-        if (pt.x >= rois[0].x && pt.y >= rois[0].y && pt.x <= rois[0].br().x && pt.y <= rois[0].br().y)
+        if (rois[0].contains(keypoint.pt))
             tl_rect_count++;
-        else if (pt.x >= rois[1].x && pt.y >= rois[1].y && pt.x <= rois[1].br().x && pt.y <= rois[1].br().y)
+        else if (rois[1].contains(keypoint.pt))
             br_rect_count++;
         else
             bad_count++;
     }
 
-    ASSERT_GT(tl_rect_count, 0);
-    ASSERT_GT(br_rect_count, 0);
-    ASSERT_EQ(bad_count, 0);
+    EXPECT_GT(tl_rect_count, 0);
+    EXPECT_GT(br_rect_count, 0);
+    EXPECT_EQ(bad_count, 0);
 }
 
 #endif // HAVE_OPENCV_XFEATURES2D
 
 TEST(ParallelFeaturesFinder, IsSameWithSerial)
 {
-    Ptr<detail::FeaturesFinder> para_finder = makePtr<detail::OrbFeaturesFinder>();
-    Ptr<detail::FeaturesFinder> serial_finder = makePtr<detail::OrbFeaturesFinder>();
+    Ptr<Feature2D> para_finder = ORB::create();
+    Ptr<Feature2D> serial_finder = ORB::create();
     Mat img  = imread(string(cvtest::TS::ptr()->get_data_path()) + "stitching/a3.png", IMREAD_GRAYSCALE);
 
     vector<Mat> imgs(50, img);
     detail::ImageFeatures serial_features;
     vector<detail::ImageFeatures> para_features(imgs.size());
 
-    (*serial_finder)(img, serial_features);
-    (*para_finder)(imgs, para_features);
+    detail::computeImageFeatures(serial_finder, img, serial_features);
+    detail::computeImageFeatures(para_finder, imgs, para_features);
 
     // results must be the same
     for(size_t i = 0; i < para_features.size(); ++i)
     {
         Mat diff_descriptors = serial_features.descriptors.getMat(ACCESS_READ) != para_features[i].descriptors.getMat(ACCESS_READ);
-        ASSERT_EQ(countNonZero(diff_descriptors), 0);
-        ASSERT_EQ(serial_features.img_size, para_features[i].img_size);
-        ASSERT_EQ(serial_features.keypoints.size(), para_features[i].keypoints.size());
+        EXPECT_EQ(countNonZero(diff_descriptors), 0);
+        EXPECT_EQ(serial_features.img_size, para_features[i].img_size);
+        EXPECT_EQ(serial_features.keypoints.size(), para_features[i].keypoints.size());
     }
 }
 

modules/stitching/test/test_precomp.hpp

@@ -9,4 +9,8 @@
 #include "opencv2/stitching/detail/matchers.hpp"
 #include "opencv2/stitching/detail/blenders.hpp"
 
+#ifdef HAVE_OPENCV_XFEATURES2D
+#include "opencv2/xfeatures2d/nonfree.hpp"
+#endif
+
 #endif

samples/cpp/stitching.cpp

@@ -8,7 +8,6 @@
 using namespace std;
 using namespace cv;
 
-bool try_use_gpu = false;
 bool divide_images = false;
 Stitcher::Mode mode = Stitcher::PANORAMA;
 vector<Mat> imgs;
@@ -24,7 +23,7 @@ int main(int argc, char* argv[])
 
     //![stitching]
     Mat pano;
-    Ptr<Stitcher> stitcher = Stitcher::create(mode, try_use_gpu);
+    Ptr<Stitcher> stitcher = Stitcher::create(mode);
     Stitcher::Status status = stitcher->stitch(imgs, pano);
 
     if (status != Stitcher::OK)
@@ -47,9 +46,6 @@ void printUsage(char** argv)
          "Flags:\n"
          "  --d3\n"
          "      internally creates three chunks of each image to increase stitching success\n"
-         "  --try_use_gpu (yes|no)\n"
-         "      Try to use GPU. The default value is 'no'. All default values\n"
-         "      are for CPU mode.\n"
          "  --mode (panorama|scans)\n"
          "      Determines configuration of stitcher. The default is 'panorama',\n"
          "      mode suitable for creating photo panoramas. Option 'scans' is suitable\n"
@@ -75,19 +71,6 @@ int parseCmdArgs(int argc, char** argv)
             printUsage(argv);
             return EXIT_FAILURE;
         }
-        else if (string(argv[i]) == "--try_use_gpu")
-        {
-            if (string(argv[i + 1]) == "no")
-                try_use_gpu = false;
-            else if (string(argv[i + 1]) == "yes")
-                try_use_gpu = true;
-            else
-            {
-                cout << "Bad --try_use_gpu flag value\n";
-                return EXIT_FAILURE;
-            }
-            i++;
-        }
         else if (string(argv[i]) == "--d3")
         {
             divide_images = true;

samples/cpp/stitching_detailed.cpp

@@ -17,6 +17,10 @@
 #include "opencv2/stitching/detail/warpers.hpp"
 #include "opencv2/stitching/warpers.hpp"
 
+#ifdef HAVE_OPENCV_XFEATURES2D
+#include "opencv2/xfeatures2d/nonfree.hpp"
+#endif
+
 #define ENABLE_LOG 1
 #define LOG(msg) std::cout << msg
 #define LOGLN(msg) std::cout << msg << std::endl
@@ -374,23 +378,20 @@ int main(int argc, char* argv[])
     int64 t = getTickCount();
 #endif
 
-    Ptr<FeaturesFinder> finder;
-    if (features_type == "surf")
+    Ptr<Feature2D> finder;
+    if (features_type == "orb")
     {
-#ifdef HAVE_OPENCV_XFEATURES2D
-        if (try_cuda && cuda::getCudaEnabledDeviceCount() > 0)
-            finder = makePtr<SurfFeaturesFinderGpu>();
-        else
-#endif
-            finder = makePtr<SurfFeaturesFinder>();
+        finder = ORB::create();
     }
-    else if (features_type == "orb")
+#ifdef HAVE_OPENCV_XFEATURES2D
+    else if (features_type == "surf")
     {
-        finder = makePtr<OrbFeaturesFinder>();
+        finder = xfeatures2d::SURF::create();
     }
     else if (features_type == "sift") {
-        finder = makePtr<SiftFeaturesFinder>();
+        finder = xfeatures2d::SIFT::create();
     }
+#endif
     else
     {
         cout << "Unknown 2D features type: '" << features_type << "'.\n";
@@ -435,7 +436,7 @@ int main(int argc, char* argv[])
             is_seam_scale_set = true;
         }
 
-        (*finder)(img, features[i]);
+        computeImageFeatures(finder, img, features[i]);
         features[i].img_idx = i;
         LOGLN("Features in image #" << i+1 << ": " << features[i].keypoints.size());
 
@@ -443,7 +444,6 @@ int main(int argc, char* argv[])
         images[i] = img.clone();
     }
 
-    finder->collectGarbage();
     full_img.release();
     img.release();
 

samples/python/stitching.py

+#!/usr/bin/env python
+
+'''
+Stitching sample
+================
+
+Show how to use Stitcher API from python in a simple way to stitch panoramas
+or scans.
+'''
+
+from __future__ import print_function
+import cv2 as cv
+import numpy as np
+import argparse
+import sys
+
+modes = (cv.Stitcher_PANORAMA, cv.Stitcher_SCANS)
+
+parser = argparse.ArgumentParser(description='Stitching sample.')
+parser.add_argument('--mode',
+    type = int, choices = modes, default = cv.Stitcher_PANORAMA,
+    help = 'Determines configuration of stitcher. The default is `PANORAMA` (%d), '
+         'mode suitable for creating photo panoramas. Option `SCANS` (%d) is suitable '
+         'for stitching materials under affine transformation, such as scans.' % modes)
+parser.add_argument('--output', default = 'result.jpg',
+    help = 'Resulting image. The default is `result.jpg`.')
+parser.add_argument('img', nargs='+', help = 'input images')
+args = parser.parse_args()
+
+# read input images
+imgs = []
+for img_name in args.img:
+    img = cv.imread(img_name)
+    if img is None:
+        print("can't read image " + img_name)
+        sys.exit(-1)
+    imgs.append(img)
+
+stitcher = cv.Stitcher.create(args.mode)
+status, pano = stitcher.stitch(imgs)
+
+if status != cv.Stitcher_OK:
+    print("Can't stitch images, error code = %d" % status)
+    sys.exit(-1)
+
+cv.imwrite(args.output, pano);
+print("stitching completed successfully. %s saved!" % args.output)