Paul H. Paulino’s latest article on auxiliary maps.
In this series of articles, I’m going to talk about auxiliary maps and how you can use them in your VFX texturing and shading workflow. Keep in mind that these techniques I’m going to showcase are mainly focused on assets with multi tiles UV’s (UDIM). These concepts might not apply to a game pipeline.
In this article I’m going to share five different ways you can extract your Ambient Occlusion map (aka AO) and I’ll also demonstrate a simple technique in MARI to use your Ambient Occlusion to create interesting Dust/Dirt masks. I’ll give you a step-by-step tutorial and also highlight PROS and CONS of each technique based on the final quality of the map and the time it took to extract. This way you can choose the option that fits your purpose.
Again, keep in mind that this is my personal experience and these are the software that I had the opportunity to work with in the past year and a half that I’ve been working in the VFX industry.
We often call these maps Auxiliary Maps for an obvious reason: they are going to assist us during our texturing/shading process. I don’t want to get crazy technical here, so I’m going to share with you this quote from Wikipedia on AO: “attempts to approximate the way light radiates in real life, especially off what are normally considered non-reflective surfaces”
Here you can see how does an AO map look like. As you can see, the occluded areas are fading into black, and the unoccluded areas are white. The inverted version of the maps will be extremely handy for us in the future and you’re going to understand why.
As a texture painter, usually the map baking process is our first step as soon as we have approved UV’s and model. This process might take a while depending on how large, how many UV tiles and also the resolution you’re baking your maps.
In this article, I’m going to focus on how you can extract maps from your models so you can use it anywhere (MARI, Photoshop, Substance, etc.), but you can also use procedural Ambient Occlusion nodes using software such as V-ray and Arnold. One thing you might consider if you working on shaders for VFX: using AO procedural nodes can slow down your render times considerably, so keep that in mind. It works well for still images, but if you are going to render something in movement, it might be better to use baked maps.
Before we jump into the baking process, I would like to highlight a few steps that you should consider.
Import your mesh into Zbrush. Make sure to have it with enough subdivisions (4 million polys or more)
Go to Zplugin > Multi-Map Exporter.
On the screenshot below I highlighted the areas that you should pay more attention while adjusting your settings.
Occlusion Intensity: This slider increases the Ambient Occlusion Intensity making the ambient occlusion areas larger and darker.
ScanDist: Scan Distance increases the distance of the secondary color in the Ambient Occlusion.
Aperture: Aperture affects the scale of the Ambient Occlusion, with smaller values giving a softer affect.
After adjusting the settings, just click on Create all maps.
Here’s the Zbrush AO map preview in MARI.
Now that we know several methods to extract our Ambient Occlusion Map, how are we going to use it?
On the video below, I showcase a quick technique that I’ve been using quite a lot on my personal work. It might look simple, but if you understand the principle, you will be able to achieve incredible results without too much effort.
And that’s not the only way to use Ambient Occlusion maps. You can be creative with this map and use it to enhance your diffuse and specular maps. Or maybe use it on your bump to erase some areas and get a more organic look.