What's happening with the AO?
polycounter lvl 5
Hello,
does someone know why the interior of my pot is almost black (I mean the ambient occlusion bake from 3ds max...)?
And another question:
Isn't it possible to bake ambient occlusion with the default renderer? I always have to switch to mental ray. But mental ray doesn't bake the normal-maps properly... so I always need to switch back and forth...
Thx for help!
does someone know why the interior of my pot is almost black (I mean the ambient occlusion bake from 3ds max...)?
And another question:
Isn't it possible to bake ambient occlusion with the default renderer? I always have to switch to mental ray. But mental ray doesn't bake the normal-maps properly... so I always need to switch back and forth...
Thx for help!
Replies
even in the real world, the inside of a bucket would be shadowed, the light being occluded by the bucket itself.
Anyway, mind showing us your baking setup?
I would think so, this ao bake would make it pretty useless if it got flipped over in a game.
My bet would be on the highpoly pot overhead.
AO is pretty much only contact shadows.
No this happens a lot with objects like this. I will usually put an omni light inside the object with a low brightness to lighten up the inside.
I guess upping the number of light bounces might fix this but it'll make your rendering time take a lot longer.
"ambient occlussion" does not calculate any bounces at all, its simply a occlusion factor of the surface. It casts a bunch of rays in a dome from every point on the surface and whatever fraction is occluded is how dark the surface is.
You can set a max distance though so rays don't travel forever (or to the other side of the bucket).
AO totally disregards scene lights, all it does is measure distance to nearby occluders. Like Jordan said, just shorten the max distance so the rays wont get to the bucket sides.
That depends how you bake it. I almost always bake with the scanline, using a skylight. This way, I can use scene lights if I want to, and I bake out a shadowmap. I tend to like the results much, much better than the actual MR AO.
2) Are you sure you're baking AO and not a diffuse map with lights and shadows turned on? That's pretty weird.
3) Do you have any overlapping pieces in your UV layout? They should be moved outside of the 0:1 space, preferably exactly one tile to the left, right up or down.
You can do this by using the type in coordinates box at the bottom of the UV editor.
Turn on #1 and in #2 type 1.0 and hit enter.
Out of interest how do you feel light tracer is better? I'm yet to find a scenario where mental ray cant do the same job with more control.
It really boils down to what you need. If you're trying to bake in a particular lighting effect like a top down light where the object is more shaded on the bottom than on top.
Or you want shadows cast from objects that aren't going to occlude.
Or you might want an overall gradient that would be hard to apply to a jumble of UV pieces.
Or you might have objects that glow on the character and you want to capture the light, then scene light work pretty well.
If you want a pits and peaks view of the surface MentalRay AO.
Personally I'm not a big fan of using a skylight and light tracer, I find it just as slow as MRAO, but instead I go with a standard light dome. There are a few scripts around plus you can build one and import it into whatever scene.
Neither is better than the other (but I do have padding issues and normal background color issues with MR) when everything works like it should but that doesn't mean you'll use one or the other in every single case.
Baking any ray traced shaders is much faster in mental ray. If you want a light tracer style render you use Final Gather and put a low distance high spread AO map on top of it. its faster to render and just as smooth.
*If you're trying to bake in a particular lighting effect like a top down light where the object is more shaded on the bottom than on top.
FG is great for this, and its doesn't slow down to a crawl when you add a light bounce. (like i said AO for the fine crevices)
*Or you want shadows cast from objects that aren't going to occlude.
Not sure what you mean by this one
*Or you might want an overall gradient that would be hard to apply to a jumble of UV pieces.
I usually just apply a planar map to uv channel 2 or 3 and use that for the gradient.
*Or you might have objects that glow on the character and you want to capture the light, then scene light work pretty well.
FG again
Im not trying to say your wrong because I know you know your stuff, but i think you might be plesently suprised
The mental ray padding makes it unusable, no matter what you're baking. I'm not sure which version it started doing it 2011 or 2012 but I can't use it until they fix it. That's total garbage. Not to mention it applies the wrong background color to the normal map, even if its set correctly in RTT. Annoying but can be worked around.
Until this padding issue popped up I was happy using mental ray for almost everything. The speed difference really doesn't bother me that much the maps I bake aren't that complex or huge and I have a micro render farm I send them off to if they do take up too much of my time.
You can kind of see the padding issue on in the original post. Its a big map with a low padding setting, but it will still generate seams... How does anyone at Autodesk think that's acceptable "padding"?
You won't have any direct light effects or shadows with Mental Ray AO output, due to the way it's calculated so you can render MRAO all day tweaking light settings and nothing is going to change.
I've done that before and that works in some cases but sometimes the planar map angle doesn't treat the non-planar faces well and shows stretching. By doing the gradient with lights you mostly get around that.
I was mostly talking about the difference between baking in lighting and using just MentalRay AO map output from RTT. It doesn't matter which render you use to bake the lighting AO map output, won't be effected by lights in the scene.
excellent point, I hadn't considered that.
Im going to do some side by side speed tests, If the results are interesting ill post em.
edit: point taken the seam issue in 2011+ is a killer.
I've found that mental ray always puts this grain across renders. The light tracer just appears smoother. You can see the grain in the OP's image. However sometimes mental ray is useful for other reasons.
true but its better to use FG if you want a super smooth render. then put a low distance ao map over the top.
like mark said though the most recent versions of max have broken fg baking
xNormal is quite good as well, but it doesn't support multiple UV channels...
spread had nothing to do with this. spread controls how wide the cone of rays is.
If you have a scene set up with lights and layers you can just dump your models in the scene and a lot of the work is done.
I have solved the problem by playing around with the max distance. Before it was set to 0... apparently 0 equals for infinitive distance (can this be?!)
In my first post's photo the object above my AO-Object is just the high poly I moved upwards to have a better look on the Lop-Poly. I was baking the AO from High-poly model to the low-poly.
Here are my new results after playing around with the max dist.
I didn't know that xnormal can bake AO too, next time I will go for it... But for simple objects like this I still want to be able to do the render quickly in 3ds max.
And what about Light tracer... I can't select that renderer.. or isn't it a renderer?
http://www.laurenscorijn.com/articles/ambient-occlusion-baking
Using a light dome is much faster than using a skylight and much more customizable. Scanline right now actually calculates edge padding correctly unlike MentalRay that just makes a mess of the padding (see examples in my previous posts).
Going to try that script out, always enjoy faster rendering