extract a continuous OpenCV cuda::GpuMat? - c++

Question

I'm trying to apply thrust algorithms to the data in cuda::GpuMats. Unfortunately OpenCV basically never produces continuous GpuMats (which screws up virtually all my algorithms, code, performance etc...). Normally, when I encounter these kinds of scenarios with discontinuous host matrices, I just clone the matrix, typically host side matrices become discontinuous when the matrix came from a rectangle view of another matrix.
This... doesn't work with gpu mats. Literally never seem to come out contiguous. I'm not sure what the heck is going on with OpenCV. All I'm doing is the following:
cv::Mat host(600,400);
cv::gpu::GpuMat device;
device.upload(host);
cv::gpu::GpuMat continuous;
if(device.isContinuous()){
continuous = device;
}else{
continuous = device.clone();
}
//always prints...
if(!continuous.isContinuous()){
std::cout << "isn't Continuous\n";
}
As you can see, the mere act of uploading data produces discontinuous data...

Answer 1

Hi Dear,
To generate continuous GpuMat, you can use one of the below methods:
use cv::cuda::createContinuous(int rows, int cols, int type, continuous_gpumat) or its overloads.
allocate a continuous Cuda memory using cudaMalloc cuda api call or similar functions, and then construct a GpuMat header for this continuous buffer:
// elem_size is depent on data type
int alloc_size = rows*cols*elem_size;
uchar *data = nullptr;
cudaError_t status = cudaMalloc(&data, alloc_size);
assert(status==cudaSuccess);
continuous_gpumat = cv::cuda::GpuMat(rows, cols, type, data);
// in destructor:
status = cudaFree(data);
assert(status==cudaSuccess);