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How to make invisible footprints appearing on the fllor

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Nick AugustineHow to make invisible footprints appearing on the fllor
by on Apr 30, 2011 at 8:13:25 am

HI everyone,

I need help with SFX in a short film : I need to make invisible footprints appear on the floor as they are moving towards the camera. Any ideas how such effect can be achieved?

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Tudor "Ted" JelescuRe: How to make invisible footprints appearing on the fllor
by on Apr 30, 2011 at 3:28:33 pm

Depending on the way you have designed the shot you may need to match a camera move or not. If that is the case, then a 3d tracker like Camera Tracker from the Foundry can help. Once you solve that (or if you do not need a camera move this is the first step), you can set a 3d layer to match the perspective of the floor. recompose that leaving all attributes in the initial comp and open the precomp. Create a grid in it by using a plugin or an image of a square grid. Use that to better match your positioning and to determine the path for your footprints.
In the precomp, which is 2d, you can now animate the footprints coming on. You can play with the look by making the footprints a solid color- black or white, add bevel and texture to them and then comp the 3d layer using different transfer modes- Screen , Add....
That's one way of doing it.

Tudor "Ted" Jelescu
Senior VFX Artist

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Jonathan ZieglerRe: How to make invisible footprints appearing on the fllor
by on May 2, 2011 at 7:42:40 pm

It depends largely on what look you are going for. Is the floor thick carpet, tile, hardwood? Presumably carpet for floor. What's the shot? Is it wide, med, closeup? What's the lighting like? There are going to be complex 3D solutions and practical solutions too.

The way it was done in the good old days of film before 3d apps, it was dummy earth that fell down in a shoe shape to appear as of it was being pushe down by some weight.

I would shoot the same shot of the carpet at the same angle as another shot of shoe shapes - have an actor walk in paint and then on some paper on the floor. May new to make it in Photoshop. Then take the image of the footsteps and over lay the carpet shot to match the perspective. Reveal footsteps one by one in AE as shadows on the carpet. It may not look like the carpet is being pushed down, but it will give with the settings and look at what actual carpet being pressed down looks like say under plexiglass.

Experiment a bit and you'll come up with something that will work.

Jonathan Ziegler

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