Ambient Occlusion

[Ryu]

Hello guys, i havent made any new models lately but as i saw recently most people are doing models for warband in NI community. So i just wanted to add a topic here to get modellers interested with ambient occlusion baking.

To put it simply; by baking ao map(ambient occlusion map) out and combining it with your model's diffuse(color) map in GIMP(or PS); you can have better looking textures; to have more volume-depth on them. It's a way to add fake shadows based on your model's geometry, basicly close surfaces gets darker and darker which leads a difference on the diffuse map to make your model look like having more "volume". To show what i'm talking about i took some real time screenshots of 2 of my lowpoly models in Blender;


On this sword's textures, i might've played with diffuse's contrast a bit, but ao map is giving the effect which i'm talking about here, check where blade meets the hilt(bladeguard, yellow part) and around the diamonds.



As you can see here, no diffuse maps; only normal map with ao map on left side, and normal map without any ao map on right side. For example notice the table's legs where it seems like it has more depth instead of being plain white.


Baking ambient occlusion mostly depends on the 3d program you're using, but the way doing it should be similar. When baking you have to be careful if you have repeating textures, or overlapping uv's since those fake shadows will be permenant and will effect parts whereever your uvs are. So probably its a better call to not using overlapping uvs if you are going to bake ao on your model's diffuse map. There might be a way of avoiding this by using 2 different sets of UV layouts for your models, but its a bit more advance method and you might have a hard time importing, showing those different uv sets in the game engine you are using(warband in our case). I havent tried it yet, or look for if its possible in warband to use 2 different uv sets; but i always think carefully when uv unwrapping by thinking how ambient occlusion bake's going to effect my model, and unwrap accordingly.

Anyways, this is just a taste how ao baking can be helpful, but looking for tutorials and studying them, for the program you are using should be done only by you. Well, good luck all the modellers out there, and dont forget to have fun .
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Edit1: Let me show a simple example;

This is how ao map looks like:




This is diffuse :



This is diffuse+ao by multiplying in GIMP:



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Edit2:

Dont forget, even if you cant do it in the 3d prog. you use; you can always import your mesh out (obj works fine for pretty much anything), bake ambient occlusion map in another program (like Blender ) and save it out as a texture.

Here is a very detailed tutorial for Blender;
http://www.katsbits.com/tutorials/blende...lusion.php

Notice that the small square window at upright corner is "Uv/Image Editor" in the last 2 picture, you can also open it by selecting it from the button at left side of "View Select Object" at below of the 3dviewport. Then you can save it out from there as a texture file.

An important note; If you are going to use Blender to bake AO map, i suggest you that before starting to whole progress, go to "World" tab in right menu in Blender; tick "Ambient Occlusion". Under the "Gather" pick "Raytrace" and increase the "Sample" to at least 16 for less noice on your ao map (you can make it 32 sample but it can take hell of a time to bake ao, or 12 to take less time; 16 sample works fine for me).

Now there is an advance tutorial page too there, here its if you want to learn more about ao in Blender (i might have to read it myself too );
http://www.katsbits.com/tutorials/blende...on_adv.php

If those seems too complicated, i can try to prepare a simpler tutorial here about importing a mesh in Blender, baking ao map and saving it out as a texture file. But please try the above tutorials first .


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PS. sorry for grammer mistakes if there is any, my Engrish skill is not that good .