Practice Barrels/Ambiant Occlusion Baking

Quokimbo

I do not know how I got to this point, but I am wondering where to go. I took some pictures the other day of textures I might want to use later. Well, one picture was of a barrel, and for practice I wanted to model a, not high poly, but higher poly barrel, try to bake out an occlusion pass and attach it to a lower poly version of it and try to get a version very similar. I have tried this before, and never gotten actual results worth posting. Well I could have posted this in the P&P but I want to know a couple of things.

1. Is the way I got to this point a weird way? I started as just practice and now I want to expand on this.

2. Should I try to model out the top? Or flat texture it in?

3. I attached the occlusion map to a flat shaded lower poly version where you would attach your normal/bump map and got a pretty good result. Is this where I need to apply the occlusion map? Or is there another place to attach this?

4. To make the color map I just put big blocks of solid color on top of the occlusion map and set it to multiply so the same detail was shown through the color. Now I will add decals and dirt and grime on to the color map but how will I incorporate that into the bump map?

Umm I hope these questions make sense, if not maybe these will help.

The barrel on the left is 840 triangles, and the 2 on the right are 384, with the occlusion map baked from the 840 attached to them.


These are the options I used to bake the occlusion map that I applied as a normal map to the lower poly version.
http://zacharyrussellphotography.com/__oneclick_uploads/2008/10/baking-options.jpg

This is the occlusion map that I applied as a bump map.
http://zacharyrussellphotography.com/__oneclick_uploads/2008/10/baked.jpg

I think I said this before, but I hope someone can make sense of my mayhem.

ADDED: Is ambient spelled with an e? not an A? Will someone replace that please...damn lol

Eric Chadwick

Yes, it's spelled ambient.

Ambient occlusion (AO) doesn't really makes sense for a mesh that has no real indentations or overlaps. AO is basically a way to add soft shadows to the indentations or crannies of a mesh. The ribs on a barrel don't really have enough detail to warrant baking a map, just paint soft dark lines on your diffuse instead.

Also don't use the AO map as a bump map, doesn't make sense. The normal map baked from your high-poly mesh is enough to handle the large details like the ribs. Combine painted or photograph details into your normal map:
http://wiki.polycount.net/Normal_Map#Painting

Your high-poly mesh should be smoothly curved, not faceted like the low-poly mesh. See here:
http://wiki.polycount.net/Normal_Map#SolvingWavyLines
Especially #5.

The top of your barrel is featureless. Add a spigot or something up there.

For some great overall info about creating and combining the various passes (specular, diffuse, normal) see the first link here.
http://wiki.polycount.net/Normal_Map#Tutorials

rhoymand

1. for most game modelers it easier to create a lowpoly model first, then duplicate it and create a high poly. don't be stingy with the high poly! you'll want that detail when you bake a normal map.

2. if by the top you mean the top rim, then its really up to you. of course the more geometry the better. but this all really depends on how the barrel will be viewed. I made a quick barrel test myself to see how lowpoly I can make it. as you can see its only a 48tri cylinder, but it holds up next to a high poly barrel.



3. if you bake out an AO map it should be multiplied on top of your main diffuse map. it looks like you're baking out the AO map the old way I used to do it. nowadays I just bake out the AO map and the normal map at the same time using 'transfer maps' in maya.

4. this part is a little iffy. I'm not quite sure about the pipeline to this myself, but I would add the dirt/scratches on the diffuse map, run it through the nvidia normal map filter, and then take that normal map and combine it with the one maya baked out.

EarthQuake

rhoymand wrote: »

1. for most game modelers it easier to create a lowpoly model first, then duplicate it and create a high poly. don't be stingy with the high poly! you'll want that detail when you bake a normal map.

2. if by the top you mean the top rim, then its really up to you. of course the more geometry the better. but this all really depends on how the barrel will be viewed. I made a quick barrel test myself to see how lowpoly I can make it. as you can see its only a 48tri cylinder, but it holds up next to a high poly barrel.



3. if you bake out an AO map it should be multiplied on top of your main diffuse map. it looks like you're baking out the AO map the old way I used to do it. nowadays I just bake out the AO map and the normal map at the same time using 'transfer maps' in maya.

4. this part is a little iffy. I'm not quite sure about the pipeline to this myself, but I would add the dirt/scratches on the diffuse map, run it through the nvidia normal map filter, and then take that normal map and combine it with the one maya baked out.

#1 is wrong, and shows you have no idea what "most game modelers" do. Any experienced artist knows in most cases, it will be beneficial to model your highres first, and your lowres afterwords. This way you're conforming the shape of your lowres to your high, not the other way around. For something like a barrel, it really does not matter, but this is very poor advice to try and present as fact.

Mark Dygert

#1) It really depends on the object. But for most of what I do, EQ is dead on. High first, low poly second. If you do low before high there is so much that could change. It leads to a bunch of remodeling and re-unwrapping, just a pain in the ass. Often in the case of environment work depending on how you maintain your history/modifier stack creating the low is VERY easy from the high.

In 3dsmax its also easy to optimize by using collapse and remove edges without it effecting your UV layout. I'll unwrap some high poly objects and apply procedural materials to get my diffuse started. Having the low 25-50% unwrapped already is pretty nice.

rhoymand

EarthQuake wrote: »

#1 is wrong, and shows you have no idea what "most game modelers" do. Any experienced artist knows in most cases, it will be beneficial to model your highres first, and your lowres afterwords. This way you're conforming the shape of your lowres to your high, not the other way around. For something like a barrel, it really does not matter, but this is very poor advice to try and present as fact.

sorry, I was just echoing something I read from a normal map article/tutorial
http://www.bencloward.com/tutorials_normal_maps10.shtml

"A lot of artists in the game industry are more comfortable creating low poly models. If that's you, you'll probably want to create the low poly model first. This gives you very fine control over the low poly mesh. (Sometimes resing down a high poly model, like in the previous method, gives you a very messy mesh.) Once you've got a low poly model you're happy with, make a copy of it. This copy will become your high poly version. Just subdivide it several times. The Mesh Smooth modifier in 3DS Max works well for this. Now go in and add all the detail that you've always wanted to add but couldn't because of your polygon budget. "

Mark Dygert

Yea, for the first few models it might help to go Low > High > Tweak Low. But once you get the hang of it, its faster just to go High > Low. The wording in that post might be a touch too polite for its own good.

uschi

back to AO baking:
i have a high-res (176k tris) vehicle that ive been trying to bake occlusion to combine with a color map to use on the low-res version. all of the bolts render out black, as do some bars i have at the top as part of a vent (some bars render white, some grey and some black actually)

the normals are not flipped and if i separate a bolt and bake ao (assign bake set, then Batch Bake (mental ray) bake to texture, bake shadows) on the bolt it's fine. doesn't matter which side of the vehicle theyre on, either

any ideas?