bump maps with mib_ptex_lookup in maya 2013

[ronviers]

what is the correct way to use bump maps with the mib_ptex_lookup and mia_material_x in maya 2013?

thanks
ron

[bart]

We'd just like to clarify. Are you asking for using a ptex image for a bump map?

mib_ptex_lookup will do a texture lookup and return a color from the texture. What is the representation in the texture? Or, how do you want that color interpreted?

Or are you talking about a ptex with multiple layers, one being the bump?

[ronviers]

i am trying to use bump and normal maps i paint or extract from mudbox but i have not been able to get them to work

[bart]

So you are using the ptex lookup to feed into a bump2d node, configured either for bump or normal, and then that is being connected to mia x? The standard bump slot?

Do you have a simple scene object plus ptex you can post here for example?

[ronviers]

that is correct. also tried using the mib_color_aplha and maya's luninance node. the only thing i get anything from is feeding a normal map, from ptex lookup, into the vector slot of the mia_roundcorners and using that in standard or overall. but it doesn't look right and i'm not even sure if it should.
i will post a scene a little later.
thanks

[bart]

So the key question is, what is the format of your ptex bump? Is it a normal?

The bump2d node is using a single scalar (floating point) value as if it affects height, and converting that to a normal that is used in the standard bump input of the mia x shader.

If for example, you have bump height in the red channel of the ptex texture, than you can map the r channel of the ptex lookup to the bump value in the bump2d. Or you could average r, g, and b, or use color intensity.

[ronviers]

this is how i thought it should work:
https://picasaweb.google.com/1091129...70351071688866

notice though that i am only feeding ptex lookup into diffuse to demonstrate that the image is coming from mudbox as greyscale, no normals are being perturbed

[bart]

Then, you could just map the red channel to the bump value, right? You shouldn't need an alpha node of any sort in the middle.

[ronviers]

i tried it that way too. attached is a file, with a very low res bump, that demonstrates the ways i have tried to get it to work

and here is a grab of the hypershade
https://picasaweb.google.com/1091129...77858066628146

[bart]

Got your example. First I tried just plugging it into the diffuse color, or the additional color for even less processing, but I got nothing.