Re: Image sequence / math question...

The color or the alpha of an image is not a single value, so if you want to get one value that you can use for something else, as in for example, a the translation of an object, you have to tell Maya which pixel to look at. Maya has the colorAtPoint command for this purpose.

Here's an example of an expression that will set the .translateY of a cylinder to the alpha value of a texture.

float $u = pCylinder1.translateX;
float $v = pCylinder1.translateZ;

float $alpha[] = `colorAtPoint -o A -u $u -v $v file1`;
pCylinder1.translateY = $alpha[0];

By moving the cylinder in x or z, it picks up a different alpha value and sets the translateY accordingly.