Alpha not showing reflections

[zovex]

I am trying to composite an object into a scene, i have the object casting raytraced shadows onto a plane with use background shader on it. The problem is that I cannot get the reflection to show up in the alpha channel. I intend on using another software package to composite so i need that information.

[gmask]

In reply to:
I am trying to composite an object into a scene, i have the object casting raytraced shadows onto a plane with use background shader on it. The problem is that I cannot get the reflection to show up in the alpha channel. I intend on using another software package to composite so i need that information.

I'm not sur ethat there is a way to put the reflection into the transparency inside maya for composite rendering but I think if you ADD the luminance of the layer to the transparency in composite that it would give you the effect you are looking for.

So basically you extract the alpha and the luminance from the color channels and ADD them and then use the result as your alpha for the color.

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[zovex]

That should work out but my essential problem is that i cannot get the outline of the reflection in alpha, i am not worried yet about the actually luminance values, i just need to be able to remove the entire reflection from the rest of the image.

[sunil_born2win]

I think you definitely need to composite it ...

Alban