features2d: don't use rand(), because it is not thread-safe

alalek · alalek · commit 8be1ba708e97 · 2017-08-02T23:48:54.000+03:00
Results are not stable with srand()
diff --git a/modules/features2d/src/kaze/AKAZEFeatures.cpp b/modules/features2d/src/kaze/AKAZEFeatures.cpp
@@ -2077,7 +2077,7 @@ void generateDescriptorSubsample(Mat& sampleList, Mat& comparisons, int nbits,
     }
   }
 
-  srand(1024);
+  RNG rng(1024);
   Mat_<int> comps = Mat_<int>(nchannels * (int)ceil(nbits / (float)nchannels), 2);
   comps = 1000;
 
@@ -2089,7 +2089,7 @@ void generateDescriptorSubsample(Mat& sampleList, Mat& comparisons, int nbits,
   samples = -1;
 
   for (int i = 0; i < npicks; i++) {
-    int k = rand() % (fullM.rows - i);
+    int k = rng(fullM.rows - i);
     if (i < 6) {
       // Force use of the coarser grid values and comparisons
       k = i;

Original file line number	Diff line number	Diff line change
`@@ -2077,7 +2077,7 @@ void generateDescriptorSubsample(Mat& sampleList, Mat& comparisons, int nbits,`
`2077`	`2077`	`}`
`2078`	`2078`	`}`
`2079`	`2079`
`2080`		`- srand(1024);`
	`2080`	`+ RNG rng(1024);`
`2081`	`2081`	`Mat_<int> comps = Mat_<int>(nchannels * (int)ceil(nbits / (float)nchannels), 2);`
`2082`	`2082`	`comps = 1000;`
`2083`	`2083`
`@@ -2089,7 +2089,7 @@ void generateDescriptorSubsample(Mat& sampleList, Mat& comparisons, int nbits,`
`2089`	`2089`	`samples = -1;`
`2090`	`2090`
`2091`	`2091`	`for (int i = 0; i < npicks; i++) {`
`2092`		`- int k = rand() % (fullM.rows - i);`
	`2092`	`+ int k = rng(fullM.rows - i);`
`2093`	`2093`	`if (i < 6) {`
`2094`	`2094`	`// Force use of the coarser grid values and comparisons`
`2095`	`2095`	`k = i;`