why should the disparity value in sgbm be divisble by 16?

Question

I am working on opencv sgbm(semi global block matching) function. Here two parameters (minDisparity and numberOfDisparities) are used. In that why numberOfDisparities values should be divisible by 16?

Answer 1

Probably to simplify the code internally, which uses SSE2. In general, SSE2 instructions:

• Work on multiple numbers simultaneously; having the total number of pieces of information be evenly divisible makes things simpler.
• SSE2 requires 128-bit (16 byte) memory alignment; alignment can be more easily maintained when things are nice multiples of 16...

If you examine the OpenCV source code, you'll see lots of SSE2 code for the SGBM algorithm.