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Camera Distortion
Hi, I’m currently creating a project template which I need to update every few weeks with different footage. Basically my colleague who does 3D has built some 16:9 boxes in XSI with a camera move around them which I am compositing footage on to.
We’ve researched getting the camera data from XSI to AE but without much success so we are tracking the shots in PFTrack. All the shots track absolutely perfectly as we have built in several track markers but when we bring the shots in to AE and composite 16:9 footage (or solids as place holders) on to them they are distorted and appear to be more like 15:9 and so the footage doesn’t sit on top of the boxes correctly – there is a gap either side.
As I said, the track is spot on and they stick to the boxes fine, it’s just that they don’t fit right. We are using 2112 x 1188 (16:9) comps so we can stretch we footage if needs be. The camera film back sizes and focal lengths from XSI to PFTrack to AE all match up perfectly – Film size 4.8006mm (0.189 in), focal length 10.67mm, Angle of view 25.35 so I’m at a loss to understand what is going on.
We have tried several different focal lengths to achieve different angles of view with the same results every time. I’ve also roughly composited a 3D 2112 x 1188 solid on to the one of the boxes without a camera and it seemed to fit better although it is hard to tell as it could be anywhere in 3D space. But when I turned on a camera 35mm,50mm or 85mm it seemed to distort it again!?
Sorry to go, thought I’d give as much insight to the problem as I could, any help would be appreciated. Cheers.
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3 Replies
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Chris,
If I understand your problem correctly, you are matchmoving footage and then attempting to import the data and camera into after effects to align with the footage and the problem you are having is that the markers and the footage align in the matchmoving software, but not in AFX.
I have had the same problem myself. In my case, the source of the problem was the way AFX reads the matchmove data. I exported using a Maya .ma file and then imported that into AFX. It created 2 comps, one with a normal name, and one with Square in front of it. Try this, open up the comp with Square in front of it, drop your original footage into it and then scale the footage 90% in both x and y. Assuming the frame rates are the same, this should align the markers with the footage. The problem is that you now have a reduced resolution composition. Increasing comp size wont fix the problem. If you notice, the normal comp has an pixel aspect of .9 with the square having an aspect of 1, with the horizontal width scaled down to .9.
The work around I have at present is not ideal, but does work. Simply scale your footage up by dividing the pixel size by .9. Then output your footage from AFX. Import the large footage into your matchmoving app and do everything normally. when you import the .ma file in AFX, simply open up your Square comp and drop the normal (smaller) sized footage into it. It should now work perfectly. You will have extra space in the top and bottom of the comp. Simply resize the vertical size of the comp to the original specs and you have it.
This of course presupposes that you have the same problem as I had. If so, I hope it helps, if it is a different problem, best of luck to you.
Mike
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If you’re trying to stick footage onto the surface of the renders, you might consider this:
https://www.revisionfx.com/products/remap/
Which will allow you to map textures to UVW coordinates from a render.
Also, have you checked the footage interpretations for the render? I’m confused about the problem that you’re describing. Does the rendered footage itself appear to be the wrong aspect ratio? Does the content of the rendered footage appear distorted? Is the gap you mentioned between the rendered footage and the composition or between the footage you’re tracking in and the rendered footage? Something else entirely?
Darby Edelen
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The rendered footage is fine and is square pixel like the AE comps. I’ve been into the maya file which pftrack exports and everything in there seems to be correct. The problem seems to be when using an AE camera. As I said, when I place a 16:9 solid over the footage it fits to the box perfectly but then when I turn on a camera it then becomes squashed and it doesn’t fit right. It’s as though the AE camera is distorting 3D objects.
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