Mark Fry

[ VFX : Asylum Camera Projection ]





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Asylum Camera Projection
16 June 2011

A fast hand-held camera and a tricky matchmove have been made easier to work with using camera projections in Maya.

My goal for the matchmove tasks on the independent film pitch was to deliver a well-tracked CG camera along with some proxy geometry for the set. These assets are very useful further upstream in the VFX pipeline, allowing for interesting compositing solutions.

The CG camera for this shot began in PFTrack and was finished off in Maya. Individual frames from the plate footage were cleaned up in Photoshop and used with camera projections in Maya. For this test video I rendered out a 2D motion vector pass from Maya and applied motion blur to the shot using Nuke's VectorBlur node.

Using camera projections for this shot has a few benefits:

  • Slight misalignments between any CG elements and the plate for this tricky matchmove is no longer an issue since both the scene geometry and CG elements will be re-photographed by the same camera in Maya
  • Since everything is being rendered from the same camera, all elements will automatically have matching motion blur
  • Rotoscoping through heavy motion blur is no longer required to composite the CG elements into this fast hand-held camera move
  • Painting out the red LED tracking markers and cleaning up the plate is very simple, essentially painting on a single frame from the original footage






Projection textures in Photoshop

A single image projected onto geometry from a well-matched camera will look perfect only on the particular frame from which it is sourced.

When the camera moves to a different perspective you need to paint, clone or copy detail to expand out or fill in missing areas of the texture (parts of the scene originally hidden from view).

Often you can salvage valuable details from other frames in the sequence by copying bits over, adjusting for scale & perspective, matching colour, etc.

The CG scene needs to be divided up in a logical fashion that allows for various depths of detail to be corrected with their own texture maps. ( If geometry doesn't overlap with each other you can usually get away with sharing a texture map. )

Here are some examples of the projection texture maps I created in Photoshop.



[ click for full-size ^]












Copyright Mark Fry. All rights reserved.

Music by: Kevin Macleod

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