Archive for category: ActionScript 2 Displacement maps

I already blogged about this, but I saw that some items could use some more explanation. Please read “Getting the displacement you need” first for the basic idea.

In short the principle is:

• you have a reference map, say A
• you apply a distortion effect to the reference map created a distorted version of A say A’
• you calculate the displacement map that could transform A into A’ by calculating the difference in pixel value between A and A’

Some important points before we start:
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In my previous post I explained the basics of displacement mapping, and I promised to tell something about getting the filter to do what you want it to do. Well, in order to do so, let’s look at the picture I showed you again, written a little differently:

+

*?

=

where ? is an unknown scale factor

It says that given a source image, if we apply a displacement map multiplied by some scaling factor, we will end up with a result image. If we look at the visual formula written like this:

ImgSource + DispMap*ScaleFactor = ImgResult,

we can see that with some basic math we get:

ImgResult – ImgSource = DispMap*ScaleFactor, in other words:

–

=

*?

This tells us that if we have the source image and the result, that we can in theory calculate the displacement map, but since the displacement map is related to the scalefactor, there is not a single result.

Would this simple idea gives us the one possible displacement map that caused the transformation of ImgSource into ImgResult?

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