Doxygen tutorials: basic structure

doc/tutorials/features2d/feature_description/feature_description.markdown

@@ -0,0 +1,91 @@
+Feature Description {#tutorial_feature_description}
+===================
+
+Goal
+----
+
+In this tutorial you will learn how to:
+
+-   Use the @ref cv::DescriptorExtractor interface in order to find the feature vector correspondent
+    to the keypoints. Specifically:
+    -   Use @ref cv::SurfDescriptorExtractor and its function @ref cv::compute to perform the
+        required calculations.
+    -   Use a @ref cv::BFMatcher to match the features vector
+    -   Use the function @ref cv::drawMatches to draw the detected matches.
+
+Theory
+------
+
+Code
+----
+
+This tutorial code's is shown lines below.
+@code{.cpp}
+#include <stdio.h>
+#include <iostream>
+#include "opencv2/core.hpp"
+#include "opencv2/features2d.hpp"
+#include "opencv2/highgui.hpp"
+#include "opencv2/xfeatures2d.hpp"
+
+using namespace cv;
+using namespace cv::xfeatures2d;
+
+void readme();
+
+/* @function main */
+int main( int argc, char** argv )
+{
+  if( argc != 3 )
+   { return -1; }
+
+  Mat img_1 = imread( argv[1], IMREAD_GRAYSCALE );
+  Mat img_2 = imread( argv[2], IMREAD_GRAYSCALE );
+
+  if( !img_1.data || !img_2.data )
+   { return -1; }
+
+  //-- Step 1: Detect the keypoints using SURF Detector, compute the descriptors
+  int minHessian = 400;
+
+  Ptr<SURF> detector = SURF::create();
+  detector->setMinHessian(minHessian);
+
+  std::vector<KeyPoint> keypoints_1, keypoints_2;
+  Mat descriptors_1, descriptors_2;
+
+  detector->detectAndCompute( img_1, keypoints_1, descriptors_1 );
+  detector->detectAndCompute( img_2, keypoints_2, descriptors_2 );
+
+  //-- Step 2: Matching descriptor vectors with a brute force matcher
+  BFMatcher matcher(NORM_L2);
+  std::vector< DMatch > matches;
+  matcher.match( descriptors_1, descriptors_2, matches );
+
+  //-- Draw matches
+  Mat img_matches;
+  drawMatches( img_1, keypoints_1, img_2, keypoints_2, matches, img_matches );
+
+  //-- Show detected matches
+  imshow("Matches", img_matches );
+
+  waitKey(0);
+
+  return 0;
+  }
+
+ /* @function readme */
+ void readme()
+ { std::cout << " Usage: ./SURF_descriptor <img1> <img2>" << std::endl; }
+@endcode
+Explanation
+-----------
+
+Result
+------
+
+1.  Here is the result after applying the BruteForce matcher between the two original images:
+
+    ![image](images/Feature_Description_BruteForce_Result.jpg)
+
+