some bugfixes & improvements in openfabmap code, docs and samples by Arren Glover

samples/cpp/fabmap_sample.cpp

@@ -58,6 +58,24 @@ using namespace std;
 
 int main(int argc, char * argv[]) {
 
+    /*
+ 
+    Note: the vocabulary and training data is specifically made for this openCV
+    example. It is not reccomended for use with other datasets as it is 
+    intentionally small to reduce baggage in the openCV project.
+
+    A new vocabulary can be generated using the supplied BOWMSCtrainer (or other
+    clustering method such as K-means
+
+    New training data can be generated by extracting bag-of-words using the 
+    openCV BOWImgDescriptorExtractor class.
+
+    vocabulary, chow-liu tree, training data, and test data can all be saved and
+    loaded using openCV's FileStorage class and it is not necessary to generate 
+    data each time as done in this example
+
+    */
+
     cout << "This sample program demonstrates the FAB-MAP image matching "
         "algorithm" << endl << endl;
 
@@ -188,10 +206,9 @@ int main(int argc, char * argv[]) {
     Mat result_large(100, 100, CV_8UC1);
     resize(result_small, result_large, Size(500, 500), 0, 0, CV_INTER_NN);
 
+    cout << endl << "Press any key to exit" << endl;
     imshow("Confusion Matrix", result_large);
     waitKey();
 
-    cout << endl << "Press any key to exit" << endl;
-
     return 0;
 }