A pair of cheap usb webcams are pretty suboptimal for stereo vision. To start, they aren't synchronized. Plus you have to rig them somehow to know their relativ

A pair of cheap usb webcams are pretty suboptimal for stereo vision. To start, they aren't synchronized. Plus you have to rig them somehow to know their relative positions. They may use rolling shutter, which is bad for stereo. It's not that it can't be done, but it's not easy.