added saving of matches graph into opencv_stitching (in DOT format)

modules/stitching/main.cpp

@@ -48,6 +48,7 @@
 // 3) Automatic Panoramic Image Stitching using Invariant Features. 
 //    Matthew Brown and David G. Lowe. 2007.
 
+#include <fstream>
 #include "precomp.hpp"
 #include "util.hpp"
 #include "warpers.hpp"
@@ -83,6 +84,10 @@ void printUsage()
         "      Bundle adjustment cost function. The default is 'focal_ray'.\n"
         "  --wave_correct (no|yes)\n"
         "      Perform wave effect correction. The default is 'yes'.\n"
+        "  --save_graph <file_name>\n"
+        "      Save matches graph represented in DOT language to <file_name> file.\n"
+        "      Labels description: Nm is number of matches, Ni is number of inliers,\n"
+        "                          C is confidence.\n"
         "\nCompositing Flags:\n"
         "  --warp (plane|cylindrical|spherical)\n" 
         "      Warp surface type. The default is 'spherical'.\n"
@@ -114,6 +119,8 @@ double compose_megapix = -1;
 int ba_space = BundleAdjuster::FOCAL_RAY_SPACE;
 float conf_thresh = 1.f;
 bool wave_correct = true;
+bool save_graph = false;
+std::string save_graph_to;
 int warp_type = Warper::SPHERICAL;
 int expos_comp_type = ExposureCompensator::GAIN_BLOCKS;
 float match_conf = 0.65f;
@@ -209,6 +216,12 @@ int parseCmdArgs(int argc, char** argv)
             }
             i++;
         }
+        else if (string(argv[i]) == "--save_graph")
+        {
+            save_graph = true;
+            save_graph_to = argv[i + 1];
+            i++;
+        }
         else if (string(argv[i]) == "--warp")
         {
             if (string(argv[i + 1]) == "plane")
@@ -378,6 +391,14 @@ int main(int argc, char* argv[])
     matcher.releaseMemory();
     LOGLN("Pairwise matching, time: " << ((getTickCount() - t) / getTickFrequency()) << " sec");
 
+    // Check if we should save matches graph
+    if (save_graph)
+    {
+        LOGLN("Saving matches graph...");
+        ofstream f(save_graph_to.c_str());
+        f << matchesGraphAsString(img_names, pairwise_matches, conf_thresh);
+    }
+
     // Leave only images we are sure are from the same panorama
     vector<int> indices = leaveBiggestComponent(features, pairwise_matches, conf_thresh);
     vector<Mat> img_subset;

modules/stitching/motion_estimators.cpp

@@ -40,6 +40,7 @@
 //
 //M*/
 #include <algorithm>
+#include <sstream>
 #include "autocalib.hpp"
 #include "motion_estimators.hpp"
 #include "util.hpp"
@@ -407,6 +408,70 @@ void waveCorrect(vector<Mat> &rmats)
 
 //////////////////////////////////////////////////////////////////////////////
 
+string matchesGraphAsString(vector<string> &pathes, vector<MatchesInfo> &pairwise_matches,
+                            float conf_threshold)
+{
+    stringstream str;
+    str << "graph matches_graph{\n";
+
+    set<int> added_imgs;
+
+    // Add matches
+    for (size_t i = 0; i < pairwise_matches.size(); ++i)
+    {
+        if (pairwise_matches[i].src_img_idx < pairwise_matches[i].dst_img_idx &&
+            pairwise_matches[i].confidence > conf_threshold)
+        {
+            string name_src = pathes[pairwise_matches[i].src_img_idx];
+            size_t prefix_len = name_src.find_last_of("/\\");
+            if (prefix_len != string::npos) prefix_len++; else prefix_len = 0;
+            name_src = name_src.substr(prefix_len, name_src.size() - prefix_len);
+
+            string name_dst = pathes[pairwise_matches[i].dst_img_idx];
+            prefix_len = name_dst.find_last_of("/\\");
+            if (prefix_len != string::npos) prefix_len++; else prefix_len = 0;
+            name_dst = name_dst.substr(prefix_len, name_dst.size() - prefix_len);
+
+            added_imgs.insert(pairwise_matches[i].src_img_idx);
+            added_imgs.insert(pairwise_matches[i].dst_img_idx);
+
+            str << "\"" << name_src << "\" -- \"" << name_dst << "\""
+                << "[label=\"Nm=" << pairwise_matches[i].matches.size()
+                << ", Ni=" << pairwise_matches[i].num_inliers
+                << ", C=" << pairwise_matches[i].confidence << "\"];\n";
+        }
+    }
+
+    // Add unmatched images
+    for (size_t i = 0; i < pairwise_matches.size(); ++i)
+    {
+        if (pairwise_matches[i].src_img_idx < pairwise_matches[i].dst_img_idx)
+        {
+            if (added_imgs.find(pairwise_matches[i].src_img_idx) == added_imgs.end())
+            {
+                added_imgs.insert(pairwise_matches[i].src_img_idx);
+                string name = pathes[pairwise_matches[i].src_img_idx];
+                size_t prefix_len = name.find_last_of("/\\");
+                if (prefix_len != string::npos) prefix_len++; else prefix_len = 0;
+                name = name.substr(prefix_len, name.size() - prefix_len);
+                str << "\"" << name << "\";\n";
+            }
+            if (added_imgs.find(pairwise_matches[i].dst_img_idx) == added_imgs.end())
+            {
+                added_imgs.insert(pairwise_matches[i].dst_img_idx);
+                string name = pathes[pairwise_matches[i].dst_img_idx];
+                size_t prefix_len = name.find_last_of("/\\");
+                if (prefix_len != string::npos) prefix_len++; else prefix_len = 0;
+                name = name.substr(prefix_len, name.size() - prefix_len);
+                str << "\"" << name << "\";\n";
+            }
+        }
+    }
+
+    str << "}";
+    return str.str();
+}
+
 vector<int> leaveBiggestComponent(vector<ImageFeatures> &features,  vector<MatchesInfo> &pairwise_matches, 
                                   float conf_threshold)
 {

modules/stitching/motion_estimators.hpp

@@ -122,6 +122,10 @@ void waveCorrect(std::vector<cv::Mat> &rmats);
 //////////////////////////////////////////////////////////////////////////////
 // Auxiliary functions
 
+// Returns matches graph representation in DOT language
+std::string matchesGraphAsString(std::vector<std::string> &pathes, std::vector<MatchesInfo> &pairwise_matches,
+                                 float conf_threshold);
+
 std::vector<int> leaveBiggestComponent(std::vector<ImageFeatures> &features, std::vector<MatchesInfo> &pairwise_matches, 
                                        float conf_threshold);
 

modules/stitching/util.hpp

@@ -108,8 +108,9 @@ bool overlapRoi(cv::Point tl1, cv::Point tl2, cv::Size sz1, cv::Size sz2, cv::Re
 cv::Rect resultRoi(const std::vector<cv::Point> &corners, const std::vector<cv::Mat> &images);
 cv::Rect resultRoi(const std::vector<cv::Point> &corners, const std::vector<cv::Size> &sizes);
 cv::Point resultTl(const std::vector<cv::Point> &corners);
-void selectRandomSubset(int count, int size, std::vector<int> &subset);
 
+// Returns random 'count' element subset of the {0,1,...,size-1} set
+void selectRandomSubset(int count, int size, std::vector<int> &subset);
 
 #include "util_inl.hpp"