I was having fun re-writing their CameraServer and making a Camera API (with functions like the ones you are describing but more generalized) and was lucky enough to find this early on:
http://www.ni.com/pdf/manuals/371266e.pdf
It describes several examples and stuff that doesn't pertain to finding a Yellow Tote's center, but helpful nonetheless. Look around for NIVision IMAQdx and NIVision imaq references and documentation. It's bothersome because the Java NIVision wrapper is completely undocumented and 30,000+ lines long but it contains a lot.
Note: Not all NIVision functions are available in the Java Wrapper.
I have not done so but looking at WPILib's vision processing classes may be helpful. I am not sure but I believe you can access documentation through the start menu if you have NIVision installed. I do most of my development at home so I have not check on the team laptop.