[mikets]

Because of the fact that the vision library only gives the bounding box of the rectangular target. It is by definition inaccurate IMHO. If you have any perspective distortion, I suspect the center_mass_x/center_mass_y are going to have some amount of error anyway. So a few pixel error due to resolution is probably insignificant if your robot is close enough to the targets. If your robot is far enough, there are a lot more factors affecting your accuracy (e.g. the precision of your PID controlled turn, the variation of the shooter speed, air resistance etc.).