Census transformation

[Apeiria]

Hello,

I have a question regarding census transformation when reading your code. Why aren't you comparing the intensity of neighboring pixels with the center?

Best regards.

Here is the code in census_transform.cu

// Compute and store
const int x = x0 + tid, y = y0 + i;
if(half_kw <= x && x < width - half_kw && half_kh <= y && y < height - half_kh){
	const int smem_x = tid;
	const int smem_y = (half_kh + i) % SMEM_BUFFER_SIZE;
	feature_type f = 0;
	for(int dy = -half_kh; dy < 0; ++dy){
		const int smem_y1 = (smem_y + dy + SMEM_BUFFER_SIZE) % SMEM_BUFFER_SIZE;
		const int smem_y2 = (smem_y - dy + SMEM_BUFFER_SIZE) % SMEM_BUFFER_SIZE;
		for(int dx = -half_kw; dx <= half_kw; ++dx){
			const int smem_x1 = smem_x + dx;
			const int smem_x2 = smem_x - dx;
			const auto a = smem_lines[smem_y1][smem_x1];
			const auto b = smem_lines[smem_y2][smem_x2];
			f = (f << 1) | (a > b);
		}
	}
	for(int dx = -half_kw; dx < 0; ++dx){
		const int smem_x1 = smem_x + dx;
		const int smem_x2 = smem_x - dx;
		const auto a = smem_lines[smem_y][smem_x1];
		const auto b = smem_lines[smem_y][smem_x2];
		f = (f << 1) | (a > b);
	}
	dest[x + y * width] = f;
}

[atakagi-fixstars]

Hi, @Apeiria

Thank you for your question. We are actually using Center-Symmetric Census Transform. It compares only center-symmetric pairs of pixels.

For more information, please refer to this paper. https://www.mi.fu-berlin.de/inf/groups/ag-ki/publications/Semi-Global_Matching/caip2013rsp_fu.pdf

Regards,

[Apeiria]

Hi, @Apeiria

Thank you for your question. We are actually using Center-Symmetric Census Transform. It compares only center-symmetric pairs of pixels.

For more information, please refer to this paper. https://www.mi.fu-berlin.de/inf/groups/ag-ki/publications/Semi-Global_Matching/caip2013rsp_fu.pdf

Regards,

Thank you!