From 2219e38192f030ea3f5200280ef18fe6f1cdc74b Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <no@email>
Date: Thu, 16 Feb 2012 19:21:48 +0000
Subject: [PATCH] fix a potential crash when there are no keypoints

---
 modules/features2d/src/orb.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/modules/features2d/src/orb.cpp b/modules/features2d/src/orb.cpp
index 97f2d7a0e9..e878cff0cb 100644
--- a/modules/features2d/src/orb.cpp
+++ b/modules/features2d/src/orb.cpp
@@ -891,6 +891,8 @@ void ORB::operator()(const Mat &image_in, const Mat &mask, vector<KeyPoint> & ke
         // Get the features and compute their orientation
         vector<KeyPoint>& keypoints = all_keypoints[level];
         int nkeypoints = (int)keypoints.size();
+        if (nkeypoints==0)
+            continue;
         
         // Compute the descriptors
         if (do_descriptors)