Normal maps and rendering

stoofoo

So, stoof is trying to render out an ambient occlusion map for a model. I have created parts of the model in max in a higher poly version(adding plates and rivets and bolts. that sorta mess.) and i have a bunch of things ive done in photoshop for additional normal information. I would like to render out an occlusion map utilizing the normal map i have created. Is this possible? Max does not seem to want to do any sort of raytracing of normals for me dealing with the normals. I am guessing i am shit out of luck, but i figured I'd ask. Thanks.

Eric Chadwick

Haven't tried it, but this tut might provide clues.
http://everflow.com/support/tutorials/AO/Everflow_AmbientOcclusion1.html

Rick Stirling

It does work, I tihnk. I think it works only becuase I THINK I know what you are asking.

I have a maxscript that does this at work, it puts a grey texture on the model, a normal map in the bump slot then renders to texture using a light rig.

This bakes out an OA image.

I had a LOT of problems at the start by using a skylight and Light tracer, and had to switch to a 90-odd spotlight rig. instead.

Eric Chadwick

Oh yeah, and there's a script that sets up the lights for you, in fact there are a few...
http://www.scriptspot.com/start.asp?p=ma...eld=&Page=1

Ruz

I think 3dsmax7 can't render the ambient occlusion map to texture. 3dsmax 8 has an option for this, but only with mental ray i believe

EarthQuake

What? Max7 renders GI lightmaps perfeclty.... I use a skylight with light tracer for every single model i do. Tho rendering out 2048s with multi-sampeling can be pretty time consuming.

EarthQuake

Oh also, simply using the blue channel from your normal map as a light map can provide similar-ish results to using rendering out a GI lightmap, except no larged ambient shadows from objects that are close toegether or whatever, but on all the small details...

Ruz

earthquake. what I should have said was that max 8 has an extra option in the render to texture for rendering out Occlusion maps with MR, while max 7 does not.

Rick Stirling

Max 8 with skylight, lightracer and normal maps renders artifacts all over your textures bake - this is documented all over the internet. It can be fixed with upping the samples and stuff like that, but this adds so much render time that it is easier to use 100s of spotlights.

Eric Chadwick

Ah good info Rick. We just started using 8, but hadn't run into that yet.

The spotlights trick is so old-school! I remember using it before we had GI, in 1996 I think.

IMO the blue channel isn't a great solution since it only darkens on slopes, not in depressions. But like you say it's simliar-ish, so it works OK when you need a quickie.

Rick Stirling

Apparently you can fix it with supersampling - this certainly improved the artifacts, but the skydome is 10x faster.

EarthQuake

Rick do you have any examples so we can see the quality of your setup?

Rick Stirling

Afraid not. It's for work and I'd not show flats or even AO flats.

But I can easily describe the method:
Highpoly in Zbrush
Generate normal maps in Max

Max scripted part:
Apply a gray diffuse and the normal map to the model
Merge in the light rig, a skydome of spots plus 11 other secret herbs and spices.
Render to texture - complete map seems to work best.
Bishbashbosh.