I have created a displacement map that is being used on a cartoon face that is allowing me give a little bit of rotation to face, just as you see people do it on photos to give them a little bit of movement. it works perfectly except that every time I change the horizontal value on the displacement map I also have to move the position of the elements left or right or else it looks like its all pivoting in the center of the head and not further back in space where the neck is. can i do something so i do not have to re adjust the position manually every time i change the displacement map value?
Assuming your displacement map is a black and white gradient and your displacement effect is set to luminance or lightness:
The displacement effect will offset your cartoon face in one direction where the displacement map is above 127 Grey and the other direction where the map is below 127 grey.
Where the map is exactly 127 grey, you should get no displacement at all.
If you need the apparent pivot of your character to be where the neck is, then the neck is essentially not going to displace, so try to make the displacement map hit around 127 grey in the neck area.
Rather than painting this in Photoshop, you should be able to apply the levels effect to your displacement map to shift its brightness.
Graham Macfarlane - 3D visualisation and VFX
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