AO Baking Issues

FFQOTSA

Okay, ive been making an Ithaca M37 in MAX, and i am trying to make a cavity map. ive now attempted to bake ambient occlusion maps through both 3DS MAX and xNormal.

3DS MAX:

xNormal:

As you can see, neither of the maps look right. From what ive learnt, they should have darker areas where the light cannot reach easily. However, no such areas exist.
Its probably something really sill that i forgot to do, but if anyone knows whats up and appreciate a suggestion.
Thanks, C

EarthQuake

Looks correct to me, esp the XN one. What does the model itself look like?

If you're baking AO from an exploded high/low bake, you may want to combine an AO bake from just the lowpoly as well.

FFQOTSA

I was following this tutorial from the xNormal site: http://www.donaldphan.com/tutorials/xnormal/xnormal_occ.html

Finished model:

The tutorial says i should combine different images to create my cavity map, but i dont know if it looks right once i have done so.

Cavity attempt:

Quack!

Like EQ said, those look proper. Are these from an exploded bake?

Also your cavity won't be that prominent until you get some base colors down, but looks like it might be doing what it's supposed too.

FFQOTSA

Yeah they are form an exploded bake. This is the furthest ive gotten with a model so i had to follow another tutorial as i have no idea what im doing for texturing :P

tut: [ame="http://www.youtube.com/watch?v=bgYoXF6QmWw"]Explode a Scene for Normal Map and Ambient Occlusion Baking - 3dmotive - YouTube[/ame]

Nosslak

If you want AO from the intersections you'll need to bake it with an unexploded mesh. You can do this with either the highpoly or just the lowpoly alone (I'd recommend baking details from an exploded HP and then intersections from the unexploded LP). XNormal or Knald can help you bake AO from the lowpoly mesh, other packages can do it too but these applications have options for LPAO specifically.

Popeye9

The wiki has some great reference and links that explain different methods. http://wiki.polycount.com/AmbientOcclusionMap

Bubba91873

You can also assign a multi-sub material to your object in 3ds max and give each element of the model a different material id that matches the multi-sub material and render that in rtt. As long as the mat ids aren't touching each other just like what you would do with smoothing groups it will work and you'll get the shadows from all your objects in the scene.
You wont need to explode the model for this.

In RTT make sure in the options you check "hit only matching id's"

Example:
low poly gunbarrel has mat id 1
high poly gunbarrel should also have mat id 1

but the lp and hp grip has a mat ids of 2 and these don't touch so they wont bleed over each other.
Sounds gross but you get the point.

Xnormal cant do that but its planned for version 4.0 from what I hear.

reedweinstock

use curvature map instead (its cavity and convexity combined) . make sure you use 700 samples for you final maps.

Reed

dazzerfong

If you want 'wider' occlusion, play around with the scale a bit. Having a large scale would make your AO map looks more like a cavity, and vice-versa. At least it does in XNormal for some reason.