Cavity maps are an excellent way to emphasise finite details such as wrinkles and scales on a sculpted surface. Read on to find the best way to work with them
There are a couple of different ways to work with Cavity maps in Mudbox.
Mudbox 2012 (as well as Mudbox 2011 Subscription Advantage Pack) has a Cavity Ambient Occlusion filter, found under the Viewport Filters tab, that’s handy for real-time Cavity map display.
This is useful during sculpting, as well as for real-time presentation of a model or rendering images or turntables directly out of Mudbox.
You can also display Cavity maps in different colours to produce different effects in the viewport.
The most powerful way to work with Cavity maps, however, is to create and extract them.
There are several advantages to this method, and it couldn’t be easier.
For this example, I’m using a simple object covered in scales and spikes: a perfect example of how a Cavity map can accentuate sculpted detail.
As a Cavity map is, for the most part, a more tightened and detailed Ambient Occlusion map, the extraction method is the same as producing Ambient Occlusion maps in Mudbox.
Select Maps & Extract Texture Maps & New Operation and select Ambient Occlusion Map from the Maps to Generate list. Define the Target (or low-resolution) model. The base level is always zero. Define your Source (or high-resolution) model: typically the level containing the most detail.
Under Output Map, set Quality down to Fastest. This will produce quick results and give you a good indication of how tight your details are.
It’s always a good idea to start out with the lowest settings here; then, when satisfied, crank Quality, Image Size, Anti-aliasing, and Shadow Map Resolution up higher for a final output.
Often a Fastest setting will do for most layer blending effects. Leave Image Size and other parameters at their default settings.
The key to the Cavity Map exists in the Filter, which controls the overall filtering of shadow map calculations and is typically used to reduce any visual artifacts that appear in your extracted map.
This is achieved by increasing the Filter value. However, for your Cavity Map, you want to decrease this value to a very low number: adjust Filter to 0.0001. (In the video below that accompanies this tutorial, I reduced the value right down to 0.00001 to achieve very detailed results.)
This area is subject to the amount of detail you want to achieve in your Cavity map.
Define a Base File Name for what you want your image to be named and where you want it output.
By default, the Preview as Diffuse value should be ticked.
This will import your map as a Paint Layer and let you adjust, paint or blend your Cavity map with other texture maps. Click Extract.
The extracted image will appear as a Diffuse layer under the Paint Layers tab.
The image itself appears as black details over a white background.
The Blend Modes can be found in the pull down menu in the Paint Layers tab.
Change the Blend Mode from Normal to Multiply to see the Cavity map blended with the default material or other Diffuse maps.
See the video for more advice, including creating inverse Cavity maps and adjusting colour values.
Expert tip: Via Mudbox 2012’s File menu, you can quickly export out all of your paint layers as individual texture maps, or export entire channels out as PSDs
By Craig Barr
Posted on Monday, September 12th, 2011 at 4:47 pm under Guides, Tutorials. You can subscribe to comments. You can leave a comment, or trackback from your own site.
Tags: 3D tutorial, Autodesk, cavity map, Mudbox, tutorial
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