     {
         __host__ SrcTexObj(int _xoff, int _yoff, cudaTextureObject_t _tex_src_object) : SrcTex(_xoff, _yoff), tex_src_object(_tex_src_object) { }
 
-        __device__ __forceinline__ int operator ()(int y, int x) const override
+        __device__ __forceinline__ int operator ()(int y, int x) const
         {
             return tex2D<uchar>(tex_src_object, x + xoff, y + yoff);
         }

    {
        __host__ SrcTexRef(int _xoff, int _yoff) : SrcTex(_xoff, _yoff) {}

        __device__ __forceinline__ int operator ()(int y, int x) const override
        {
            return tex2D(tex_src, x + xoff, y + yoff);
        }


    template <
        class T,
        class Norm
    >
    __global__ void calcMagnitudeKernel(const T src, PtrStepi dx, PtrStepi dy, PtrStepSzf mag, const Norm norm)
    {
