3d tracking objects shifting

[Brandon5]

I have a query about a specific after effects tracking issue, on the first halve of the video the solid perfectly aligns with the edge of the drive, (the track was very good with a low solve error), however when I duplicate the solid and move the solid down, after I had re aligned it to the edge of the drive it shifts throughout the clip, why is this and how do I prevent this.

It’s taken me a while to figure out why objects where shifting in the project, and I’ve dialled it down to moving the z axis, it appears that if I change that particular axis of a layer they shift and do not stay in the same place. Unlike if I keep it the same from when it was added. I did indeed set ground plane and origin beforehand, inputted the correct camera information, and deleted bad tracking points but nothing has stopped it from shifting after moving the z axis. 

[Mylenium]

Your position values are extremely tiny. This will inevitably cause precision issues and a strong lens shift because the camera is infinitely long, but with a very narrow FOV. You will need to scale the scene or re-teack it with different options.

Mylenium 

[Brandon5]

Thank you for your response, I have tried to scale the scene before, I've watched a few videos on the topic and used a plug-in but didn't seam to work. Could of been a user error but I've not used it since. 

[Rick Gerard · Accepted solution]

The tracking in your sample seems to be good. When you select tracking points they must be on the same plane. The solid is aligned with that plane. If you move the Z value, you shift the layer's relationship with the original plane. Only X and Y and scale changes will keep the layer aligned with the same plane. There does not seem to be anything wrong with the original tracking, It's your only your workflow that is a problem. 

[Brandon5]

Thank you very much, that explains A lot of my issues in After Effects and other software where I've use After Effects tracking data.