displacement map problems
by Dan Roth
on
Dec 15, 2008 at 9:55:17 pm
I have a picture of a toaster and am using a pre-rendered fractal noise comp to act as a displacement map, in order to create a heat-rising-from-toaster look. The problem is that i only want the top part of the toaster picture to be displaced by the fractal noise layer but ae does not let me do this. it only gives me the option to centre/stretch to fit/ or tile the fractal noise layer, whereas i need it to displace the actuall the position it is in (i placed the fractal noise layer right above the toaster). i dont want it centred! what do i do?
Please help before more of my hairs turn white!
Thanks
Dan
Re: displacement map problems by Darby Edelen on Dec 15, 2008 at 10:11:14 pm
You either need to create a pre-comp that is the size of your toaster layer with the pre-rendered fractal placed properly inside that pre-comp, and then use the pre-comp to drive the displacement. Or you can apply displacement to a copy of your toaster and roughly mask it where you want it to be displaced. I would also recommend using some subtle Compound Blur in addition to your displacement.
Re: displacement map problems by Roland R. Kahlenberg on Dec 16, 2008 at 2:29:12 pm
You need to understand the mechanics of AE's Displacement Map plugin.
With respect to a displacement map (image), mid-level gray - RGB (127,127,127) results in no displacement for the effected layer (not the displacement map - but of course). White pixels get pushed in one direction and black in the other depending on whether you have +ve or -ve values for the horizontal and vertical displacement settings.
For your current needs, you'll need to create a displacement that is a composite of (1) a mid-level grayscale image that encompasses the areas where you do not want any displacement and (2) something similar to Fractal Noise which will cover areas where you do want displacement/distortion to occur.
Take note that displacement maps can be animated.
There are a couple of COW Tutorials on Displacement Mapping.
HTH
RoRK
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