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Problems with tracking background with mocha & 3D camera tracker

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Kasper Nørgaard
Problems with tracking background with mocha & 3D camera tracker
on Mar 19, 2013 at 12:19:19 pm

I am working on a movie and i am running into some problems. I hope someone can help me. I have worked on a small clip in about 30 hours now and nothing seams to work.

I have a clip with a "handheld" camera (shoulder rig), and i need to track a wall where blood from a head shot is splashed.

I have tried to use Mocha through After Effects CS6, tracked the background and sometimes i can see that it doesn't follow that good and changes the shape and position a little bit.
When i copy to clipboard and paste it into a null object in AE it is even worse and sometimes it doesn't follow the background at all.

I have also tried to use the Tracking i AE, but that's not good enough.
Then i found 3D camera tracker in AE, which i tried to use, but that is even more confusing. When i track the clip and right click on the position i want to follow from the tracking points and create a Null object and a 3D camera or create a Solid and a 3D camera, it seams to follow the background i have been tracking. But when i parrent my blood layer to the new Null object, it seams to have a different tracking pattern. The null object still follows the background, but the blood layer which i have parrent to the null, does not follow the null.

Any one who can help me, because i am out of ideas.

Best regards

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Vishesh Arora
Re: Problems with tracking background with mocha & 3D camera tracker
on Mar 20, 2013 at 12:01:32 pm

hello Kasper

After pasting the Tracking data to a Null Object in Ae from Mocha, Delete the Anchor Point Keyframes. It should work :)

Vishesh Arora
3D and Motion Graphics Artist
Films Rajendra


2011 3D Demo Reel:

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Kasper Nørgaard
Re: Problems with tracking background with mocha & 3D camera tracker
on Mar 20, 2013 at 3:01:07 pm

Hi i already did that.
I made a new tracking in mocha yesterday, where i tracked the background and made two track layers on the two persons and placed those layers over the BG layer, so they don't disturb the BG tracking layer. I unchecked the gear icon the two person layers, so there will be no tracking data for these, but only the background. Perspective in the motion settings is also checked.

Afterwords I checked in Mocha, that the BG Tracking shape followed the BG in the clip and it did. But when i copied to clipboard (achtor point, position, scale, rotation) and paste to Null object. Delete the achtor point from that Null and parrent a blood layer to the Null.

But the blood layer seams to scale a bit wrong and the blood layer also rotates a little a certain place in the clip. (a little, but still too much rotation)

I don't understand what the problem is, because the tracker seams to follow in mocha

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