I used auto tracking on a video of a road shot out of a truck. There are no other obects moving in the scene. The tracking looks good until I place a 3D object in the scene (Cube) It holds the ground well from the top to bottom perspective,  but it seems to slide along the road not really sticking in one place. Its not following the speed of the truck (slower). Any suggestions on how to refine this problem? Should Helper frames be inserted? Any help would be appreciated.  
 
 
Paul

Hi,
I had the same problem.
I can't  solve it and I'm using XSI 3.0.
Where is the problem ?
Thanks in advance.
 
Pedro.

When you say the tracking looks good, how did you check it ?
 
There are some possible reasons:
 
- You did not place you 3D object "on the ground". If your object is too high, or too low, it will shift
- You intrinsics parameters are not well estimated (the focal length, the distortion)
- You are trying to place objects in area where there where no trackers in MatchMover, (remember that you should always try to cover the largest area possible where you are doing the 2D tracking)
- Your tracking is not accurate enough. The solution is to try to fine tune your work in MatchMover. (You can use filters also; see online doc.)
 
Helper frame is one solution, to make sure calibration is well stucked.