From a97c2c838c702366bc650420003f79b0c2fd0464 Mon Sep 17 00:00:00 2001
From: Leonid Beynenson <no@email>
Date: Fri, 23 Mar 2012 12:06:49 +0000
Subject: [PATCH] Made small change which fixes the situation, when ORB does
 not find any descriptors on an image. Earlier ORB::operator() crashed in this
 case, since rowRange method was called for an empty matrix.

---
 modules/features2d/src/orb.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/modules/features2d/src/orb.cpp b/modules/features2d/src/orb.cpp
index 4255cced17..d6c59de761 100644
--- a/modules/features2d/src/orb.cpp
+++ b/modules/features2d/src/orb.cpp
@@ -932,7 +932,12 @@ void ORB::operator()( InputArray _image, InputArray _mask, vector<KeyPoint>& _ke
         // Compute the descriptors
         if (do_descriptors)
         {
-            Mat desc = descriptors.rowRange(offset, offset + nkeypoints);
+            Mat desc;
+            if (!descriptors.empty()) 
+            {
+                desc = descriptors.rowRange(offset, offset + nkeypoints);
+            } 
+
             offset += nkeypoints;
             // preprocess the resized image
             Mat& workingMat = imagePyramid[level];