Ambiant Occlusion in mtlx standard_surface?

Forums Solaris and Karma Ambiant Occlusion in mtlx standard_surface?

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Grendizer: Member; 375 posts; Joined: May 2014; Offline

June 29, 2022 10:03 a.m.

Hello,
Could anyone tell me how to use and plug an AO map file into a mtlx standard_surface?
I used the node MTLX tiled image, then I got a mtlxambientocclusion node, but how can I use it?
Thanks
G

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Enivob: Member; 2529 posts; Joined: June 2008; Offline

June 29, 2022 11:25 a.m.

It's a bias generator that only works in CPU mode. You can use it to mix colors/ textures (or any signature type) based upon the angles of the surrounding geometry.

Edited by Enivob - June 29, 2022 12:04:40

Attachments:
Untitled-1.jpg (352.6 KB)

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Grendizer: Member; 375 posts; Joined: May 2014; Offline

June 30, 2022 7:54 a.m.

Thanks a lot Enivob for the very informative post.
I want to adjust the AO using an AO texture map, so I did this setup: see enclosed pic. Is this correct?
As you said, when I try to render with XPU, it doesn't work. Will this be fixed in future releases?
Thanks

Edited by Grendizer - June 30, 2022 07:55:39

Attachments:
karma mtlx ao with node image.png (301.2 KB)

Houdini gamboler


jsmack: Member; 7737 posts; Joined: Sept. 2011; Offline

June 30, 2022 11:24 a.m.

Grendizer
I want to adjust the AO using an AO texture map, so I did this setup: see enclosed pic. Is this correct?

I can't tell what you're after. You want to use the AO to blend between the basecolor and a ramp driven by the basecolor auto-cast to float (which would be the red channel usually)?

Grendizer
As you said, when I try to render with XPU, it doesn't work. Will this be fixed in future releases?

Who can guess what Sidefx will or won't support in the future unless they've announced it already. I suspect they aim for CPU XPU parity with mtlx shaders.


Grendizer: Member; 375 posts; Joined: May 2014; Offline

June 30, 2022 12:43 p.m.

Well yes. The AO texture map is a black and white map (attached to this post). So I'm using the ramp to get a darker version of the base color and I plug it into the BG of the mixer. Then the AO map decides what zones are in normal color and what zones are in the darker color. I think it's the right setup but I just wanted to make sure.

Edited by Grendizer - June 30, 2022 12:45:41

Attachments:
TexturesCom_Wood_PlanksRough1_2x2_1K_ao.jpg (320.9 KB)

Houdini gamboler


jsmack: Member; 7737 posts; Joined: Sept. 2011; Offline

June 30, 2022 1:09 p.m.

Grendizer
Well yes. The AO texture map is a black and white map (attached to this post). So I'm using the ramp to get a darker version of the base color and I plug it into the BG of the mixer. Then the AO map decides what zones are in normal color and what zones are in the darker color. I think it's the right setup but I just wanted to make sure.

Right, but the ramp will give you a monochrome version of the base color. (well the red channel will be mapped to a color in the ramp) If you want the base color, but darker, consider applying gamma or scale.


Grendizer: Member; 375 posts; Joined: May 2014; Offline

June 30, 2022 3:05 p.m.

OK, got it! I'm now using a mtlxrange node instead of the MTLX ramp node. Thanks again Jsmack.

Houdini gamboler

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