Removed emptiness check from cv::hconcat and cv::vconcat. Sometimes you want to concatenate with an empty matrix.

modules/core/src/matrix.cpp

@@ -2665,7 +2665,7 @@ void cv::hconcat(const Mat* src, size_t nsrc, OutputArray _dst)
     size_t i;
     for( i = 0; i < nsrc; i++ )
     {
-        CV_Assert( !src[i].empty() && src[i].dims <= 2 &&
+        CV_Assert( src[i].dims <= 2 &&
                    src[i].rows == src[0].rows &&
                    src[i].type() == src[0].type());
         totalCols += src[i].cols;
@@ -2705,7 +2705,7 @@ void cv::vconcat(const Mat* src, size_t nsrc, OutputArray _dst)
     size_t i;
     for( i = 0; i < nsrc; i++ )
     {
-        CV_Assert( !src[i].empty() && src[i].dims <= 2 &&
+        CV_Assert(src[i].dims <= 2 &&
                   src[i].cols == src[0].cols &&
                   src[i].type() == src[0].type());
         totalRows += src[i].rows;