Author Topic: Baking alpha map from high poly  (Read 8882 times)

Hi there,

Im wondering if anyone has come across this before and found a solution.

I have a high poly mesh of a bush with a texture of a simple branch and leaves that I would like to bake down to a low poly mesh. The high poly texture has an alpha on it that I would like to preserve when I bake.

The problems seems to be that no matter what I use to bake this down to the low poly, the baker will not recognize the alpha and hence the opacity of the leaves and branch. The opacity map I get out of the baker looks like it is baking down the leaf cards and ignoring the the opacity on the high poly texture, so Im getting a whole lot of white squares, not white leaf and branch shapes.

Any idea how to work around this problem with SD or other tools?

I'm new to designer, so I would use something else - temporarily fill the alpha with a solid color (black, magenta, etc), bake that, and re-make the alpha in photoshop

Last Edit: October 23, 2015, 07:40:09 am

You can bake the texture applied to the high poly to the low poly using the "Transferred texture from mesh" baker.
Product Manager - Allegorithmic

Im not sure how filling the alpha with a solid color will help. The problem is that the alpha isnt being seen as such by any baker I use. The texture that should look like a leaf (and does when loaded onto the high poly bake in substance designer 3d view) looks like a solid square with no opacity when baked down. Or at least the opacity output does after the bake as I cant seem to get the transfer texture from mesh baker to work in SD.

@Nicolas Wirrmann
That leads me to another problem I seem to be having... the transfer texture from mesh baker is just erroring with the attached screenshot. Im not entirely sure what that means. Is there something wrong with my high poly or the texture applied to it?

What is the format of the texture ?
Product Manager - Allegorithmic

Its an RGB / 8 targa. I can see the alpha as a separate channel in photoshop but do bakers not see that?

The baker will ignore the alpha channel.
You should actually extract the alpha channel as a rgb texture and bake this image.

edit: can you post the tga causing the error please ?
Last Edit: October 23, 2015, 06:35:30 pm
Product Manager - Allegorithmic

Sadly I cant. I'll try extracting it. Thanks for the help Nicolas!

Hi Nicolas, Are you planning to add the function to not ignore the alpha channel ? It will be really usefull for baking all the channel without an handjob.

Technically it'd make all bakers slower and consume more memory. So for now, except if we find a more elegant solution, we don't plan to add it.
Product Manager - Allegorithmic

It wouldn't be possible to add an 'Include alpha channel' checkbox for such a thing? Perhaps its just a lot more work than is apparent?

It's indeed more work than it appears..
Product Manager - Allegorithmic