Unable to get surface position in front of camera

I’m trying to track a small marker on a actors shoulder in a shot. The marker is a piece of paper which is a plane and Mocha can track this ok for most of the shot. However, at one point in the track the actor’s arm swings through the shot and obscures the marker completely. This throws Mocha out.
I don’t understand how to break the track into two separate portions. Anytime I try to manually move the spline or the planar surface to pick up the track after the hand movement I either seem to break the track or most of the time I get an endless error loop saying “Unable to get surface position in front of camera”.
I’ve even tried to track the whole shot manually, but Mocha always starts throwing out the “Unable to get surface position in front of camera”.
I guess I could do two completely separate tracks on two separate layers but that seems a poor solution… :frowning:

When I get this error its over the window stays open and will not go away I have to end the task and reload mocha,I am using v3

When I get this error its over the window stays open and will not go away I have to end the task and reload mocha,I am using v3

I’m having this same problem with a manual track “Unable to get surface position in front of camera” keeps popping up–and keeps coming back even after acknowledging it with OK. Have to force quit / restart the program, but keep running into the same error…

I’m having this same problem with a manual track “Unable to get surface position in front of camera” keeps popping up–and keeps coming back even after acknowledging it with OK. Have to force quit / restart the program, but keep running into the same error…

Hi There,
It sounds like your surface is tilting beyond what mocha can handle rotation wise. The best way to solve this is to track from a center point on one layer, and then from that same center point on another layer, and combine your tracks in another program. You’ll want to use manual track for the obscured section. We are working on options in the future to combine tracks within mocha.
Please let me know if you have any questions.
Cheers,
Mary

Hi There,

It sounds like your surface is tilting beyond what mocha can handle rotation wise. The best way to solve this is to track from a center point on one layer, and then from that same center point on another layer, and combine your tracks in another program. You’ll want to use manual track for the obscured section. We are working on options in the future to combine tracks within mocha.

Please let me know if you have any questions.

Cheers,
Mary

No problem! You can also use mocha layers as hold outs for tracks. So you could garbage matte the arm moving over the shoulder if that helps you get a better track. But you will still need to use manual track for the total block out of the shoulder.
Mocha treats everything at the top of the layer pile as “closest” to the camera, and at the bottom, “furthest from the camera”. Basically this means mocha holds out top layers from the ones below them when it tracks.
I highly recommend the “learn mocha” tutorials on our website, they have little tips in there that can really help you, even if you already know a lot about our software. http://www.imagineersystems.com/learn-mocha
Let me know if you have any questions!
Cheers,
Mary

No problem! You can also use mocha layers as hold outs for tracks. So you could garbage matte the arm moving over the shoulder if that helps you get a better track. But you will still need to use manual track for the total block out of the shoulder.

Mocha treats everything at the top of the layer pile as “closest” to the camera, and at the bottom, “furthest from the camera”. Basically this means mocha holds out top layers from the ones below them when it tracks.

I highly recommend the “learn mocha” tutorials on our website, they have little tips in there that can really help you, even if you already know a lot about our software. http://www.imagineersystems.com/learn-mocha

Let me know if you have any questions!

Cheers,
Mary

Hi there,

Is your surface doing a lot of rotating towards the camera and away from it? You may need to track several chunks of the surface and put the track back together. So go from flat areas to areas of angle and stop, make another layer, go from flat areas to areas of extreme angle and stop. Copy and paste keyframes in the dope sheet.

What is happening, if you turn the grid and surface on, is that your surface is going behind “the camera” and mocha’s “camera” can not calculate negative values.

You can also just try making your surface smaller and seeing where that gets you. But extreme rotation in z space is the most common cause of this issue.

Cheers,
Mary

Hi there,
Is your surface doing a lot of rotating towards the camera and away from it? You may need to track several chunks of the surface and put the track back together. So go from flat areas to areas of angle and stop, make another layer, go from flat areas to areas of extreme angle and stop. Copy and paste keyframes in the dope sheet.
What is happening, if you turn the grid and surface on, is that your surface is going behind “the camera” and mocha’s “camera” can not calculate negative values.
You can also just try making your surface smaller and seeing where that gets you. But extreme rotation in z space is the most common cause of this issue.
Cheers,
Mary

I’m trying to track a small marker on a actors shoulder in a shot. The marker is a piece of paper which is a plane and Mocha can track this ok for most of the shot. However, at one point in the track the actor’s arm swings through the shot and obscures the marker completely. This throws Mocha out.

I don’t understand how to break the track into two separate portions. Anytime I try to manually move the spline or the planar surface to pick up the track after the hand movement I either seem to break the track or most of the time I get an endless error loop saying “Unable to get surface position in front of camera”.

I’ve even tried to track the whole shot manually, but Mocha always starts throwing out the “Unable to get surface position in front of camera”.

I guess I could do two completely separate tracks on two separate layers but that seems a poor solution… :frowning:

Thanks Mary. Ok, that makes sense and at least it means I’m not doing something fundamentally wrong. I did just about manage to get a rough track by manually moving the planar surface. However, I had to be so restrictive in the transformations, etc and also had to key so many times (as the plane moves erratically) that I would have been just as well roto 'ing by hand.
On the bright side I’ve had a crash course in advanced Mocha tracking which will come in handy in the future.

Thanks Mary. Ok, that makes sense and at least it means I’m not doing something fundamentally wrong. I did just about manage to get a rough track by manually moving the planar surface. However, I had to be so restrictive in the transformations, etc and also had to key so many times (as the plane moves erratically) that I would have been just as well roto 'ing by hand.

On the bright side I’ve had a crash course in advanced Mocha tracking which will come in handy in the future.