Fixing opencv lag

[Greg McKaskle]

The WPI libraries in LV include vision code. The code uses parallel loops -- results in parallel threads -- in case the user has set the camera faster than they can process. This is effective for keeping the lag to a minimum.

You may also want to lower the camera frame rate, though. First, there is some overhead involved in processing the frames, though hopefully you aren't decompressing the images or doing any of the expensive things. Second, the two thread approach will result in much less certainty about when the image was acquired. If you are trying to estimate time, it is likely better to run the camera at a slower, but known rate that doesn't buffer images.

The other approach of requesting an image only when you want one was used in older versions of WPILib. It worked/works far better on the 206 model than on the newer Axis cameras. There is indeed quite a bit of setup overhead and the mjpeg approach is almost required to get above 10fps.

Greg McKaskle