FAQ/3D matchmoving

From VFXPedia

Rule #1: Bake all animation and textures before exporting from your 3D app. This eliminates issues caused by differences in interpolation.

There are three common reasons why people sometimes run into trouble with matching camera moves to rendered footage:

• Scale: 3D Studio Max uses inches as its unit by default, but converts to centimetres for FBX. You may need to scale everything by 1 / 2.54.

• Pixel Aspect: Most people ensure that the comp's 3D rendered resolution matches the footage resolution, but it's easy to forget to ensure that the pixel aspect set in your 3D Renderer tool also matches the aspect of the footage being loaded. Easiest is to set it up as the default in Prefs/Comp/Frame Format, but you should double-check that the Renderer tool's pixel aspect matches that of the footage it's being merged over.

• Frame ranges: This is pretty common - people import camera animation for frames 1..10, but merge it over footage loaded for frames 0..9. The resulting single-frame offset is almost, but not quite right.

Most alignment issues can be resolved by checking these three things.

• If you are still having problems, check that your camera settings match. In particular, check the camera's angle of view, angle of view type (horizontal, vertical, diagonal), and that the film backs match.

• Fusion 6 introduced a resolution gate fit option for 3D Cameras. In prior versions, Fusion expected a vertical fit and ignored what was exported from the 3D package via .ma or FBX.

• When importing a camera from a 3D application that will also be used as a projector, make sure that the Fit Resolution Gate options on the main Controls tab as well as the Projection tab are in sync. Only the first one will automatically be set to what the 3D app was using. The latter might have to be adjusted manually.

• Even if you baked your animation you should make sure that the interpolation between keyframes is smooth or linear. If the Bezier tangents are at weird angles you might encounter slight jittering even though your keyframes are correct. See this screenshot of such an example.

For more information about FBX import, you can also look at the FBXMesh3D tool and the FBX Import page.

If the above does not help and/or you think you've found an issue not mentioned here feel free to send submit it to mailto:tech@eyeonline.com.