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Motion tracking a room and its objects

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Tommy RudmanMotion tracking a room and its objects
by on Jun 19, 2015 at 11:11:12 am

So I have some footage of a room filmed on a canon 1DC. I want to insert 3d elements into this room; for example: water slowly rising around the furniture, objects outside the window, and so on.

The problem I'm having is understanding how I will position 3d objects within a room and have them sit behind objects.

my idea was to reconstruct the room's furniture in 3d space and track them to the camera, matting them out later.

The motion tracker in cinema 4d is having some trouble understanding the dimensions of the room, as well. The camera is handheld and moving around the room but there is not a terribly large amount of change in perspective that the motion tracker might be able to latch on to.

Please let me know how you think this is best worked out.

To reiterate: I want to set something up that allows me to insert and move objects around this room, with obstructive objects being taken into account. I want an organic result.

Thank you

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Michael GoldbergRe: Motion tracking a room and its objects
by on Jun 20, 2015 at 8:04:08 pm

I can't speak much for C4D's tracker, as I don't use it. I use syntheyes for tracking, and highly recommend it. This type of scene should be no problem to track. When You get a reasonable track in any tracker, it should be able to export locations of various tracked objects. Once you have these, you can correctly position your 3D objects and render these out. For something like this, I would probably create a mask to put a CG element behind something in the video. You can position a layer at a tracked location (for example if you have a tracker locator at a chair), and create a mask for a foreground object. This layer will act as a track matte for the CG layer that goes behind. You could ofcourse create 3D geometry to replace objects in the video as well. There are more than 1 way to skin a cat. One more object would be to use mocha which is built into AE. Mocha can allow you to create planes that would also hold mask layers to mask objects out.


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