Unable to get surface position in front of camera (again)

Hi. Doing a simple rectangle manual track, no tricky angles, done halfway through and this message pops up. Kind of persistent, OK-eying it does not make it go away, cannot undo. Do I really need to redo all the work? C’mon - at least give me a chance to back out of the “unsolvable angle track” thing, please.

Hi there,

It may be that your surface is going behind the camera in mocha and corrupting the data. In mocha, problem splines and tracks can occur when the tracking data has become so skewed it goes off or “behind” camera, the keyframes the tracking data generates can throw the shape information out of order. Can you try moving the surface tool in smaller, more square corners? This might prevent manual track from not playing nice.

Thanks, Mary, but the real problem here is the unpredictability of the situation and the lack of possibility to dismiss the message and back off the rogue tracking values.

Guess its the equivalent of the dreaded “divide by zero” problem in the programmers world but I’m sure there is a way we could be given a way not to loose our manual tracking work on the second last frame of a 128 frame shot.

Sorry if I seem to rant but it makes me feel very uncomfortable to do any manual tracking not knowing if/when I will be thrown out of Mocha.


I get it. Manual Track has been on our list for a while. The good news is that it should be fixed in 5.6 when that comes out. So sorry for the delay, but we will release that build as soon as it’s out of beta and stable.


I feel your pain.

What I do for manual tracks right now, is to use a rotoshape, manually keyframing it. Then I export that to either shake or nuke as a “Destination” shape for a warper/spline warper. (I’ve had Mocha’s nuke spline warper export crash Nuke every time, so I bring it in as a rotoshape).
Then I set the in and out points for that shape in Mocha to be only 1 frame long… like frame 35. Export that as the “Source”.

warpers aren’t as fast, but you can always add 4 small squares (one in each corner region) and track that to convert it to a track.

If it’s a screen with no real corners, like the iPhone (rounded), then I use a fairly complex roto shape that follows the actual edges. I also put my 4 squares on there too. then when I make key frame adjustments to the edge, I make sure I drag the appropriate nearby square along with it.
Hide the main rotoshape, retrack the 4 squares, unhide the rotoshape, delete all of the keyframes, pipe the rotoshape and squares back through the new track and retrack.
Repeat till it works.

Being able to iterate is essential.
I’ve pulled off some pretty tough tracks this way, where there was nothing to track at all, and the client needed a 3D solve in the end.


Thanks for the tip! And also, thanks for letting us know about the spline warper, we will need to look into why that is crashing.

Hey T,

Thanks for the tip. I’m using AE rather than nuke but the workflow is universally sound. Albeit only a tour de force workaround. Looking with hope to Mocha 5.6. And Black Friday :slight_smile: