diff --git a/modules/nonfree/src/surf.cpp b/modules/nonfree/src/surf.cpp index d70624e31..e6987b36f 100644 --- a/modules/nonfree/src/surf.cpp +++ b/modules/nonfree/src/surf.cpp @@ -681,8 +681,8 @@ struct SURFInvoker if( !upright ) { descriptor_dir *= (float)(CV_PI/180); - float sin_dir = std::sin(descriptor_dir); - float cos_dir = std::cos(descriptor_dir); + float sin_dir = -std::sin(descriptor_dir); + float cos_dir = std::cos(descriptor_dir); /* Subpixel interpolation version (slower). Subpixel not required since the pixels will all get averaged when we scale down to 20 pixels */