CUDA optical flow smoothing

Closes #155 (closed)

components/rgbd-sources/src/offilter.cpp

@@ -31,8 +31,9 @@ void OFDisparityFilter::filter(ftl::rgbd::Frame &frame, cv::cuda::Stream &stream
 	const cv::cuda::GpuMat &optflow = frame.getChannel<cv::cuda::GpuMat>(kChanFlow, stream);
 	frame.getChannel<cv::cuda::GpuMat>(kChanDisparity, stream);
 	stream.waitForCompletion();
-	cv::cuda::GpuMat &disp = frame.setChannel<cv::cuda::GpuMat>(kChanDisparity);
+	if (optflow.empty()) { return; }
 
+	cv::cuda::GpuMat &disp = frame.setChannel<cv::cuda::GpuMat>(kChanDisparity);
 	ftl::cuda::optflow_filter(disp, optflow, disp_old_, n_max_, threshold_, stream);
 }