A few years ago, Pixologic released a tool that changed the way some people approached modeling: ZBrush. ZBrush could be considered one of a kind because of its ability to manipulate objects with a very high level of detail. That has now changed with the arrival of XSI 6 and its Gigapolygon architecture (if you went to SIGGRAPH last year you may remember the model of the soldier, modeled to the very last detail) and Mudbox, the newest ZBrush competitor (the other one being ClayTools by SensAble. You can read about ClayTools in my SIGGRAPH report here).
Mudbox was just released on December 2006, but it had been used in production for a few years by New Zealand Studios such as WETA, and it has evolved during the years. When I first used Mudbox it felt very much like using ClayTools, save for the fact that ClayTools uses the Phantom while Mudbox uses the mouse (or tablet, if you have one). The program is extremely easy to use and intuitive. One of the reasons that always kept me away from ZBrush is that it just felt too confusing at first hand and I had to go through many pages just to begin being productive. On the other hand, Mudbox automatically became "second nature" (in part because it operates very much like Maya in terms camera navigation and tool operations).
While ZBrush and ClayTools claim to be able to handle models with "unlimited level of detail", Mudbox describes itself as a "high-resolution modeler". What it does is subdivide the model as many times as you want, or need, depending on the kind of detail you are after (I don't know if the same process is used by ZBrush or ClayTools, though). The head pictured above has nearly two million polygons, and on Skymatter's website you can see videos of Mudbox operating on 14-million polygon models. You can subdivide the model as many times as you want, and the program's core helps you handle such high resolutions because it has a "polygon cache" that stores data on the hard drive. However, the amount of subdivide operations is limited to your CPU's power. I reached the two million polygons after four subdivisions, but when I tried a fifth subdivision on an Athlon 2700+, the program crashed. I then tried the same on a Core 2 Duo laptop and it did it just fine. Opposed to the CPU usage, the amount of memory used by the model was surprisingly minimal: around 200 MB, which is less than what Maya uses when you just start the program..
In Mudbox, you manage your objects using the Object List. You have camera views, light sources, and materials, just like Maya. This is one of the things I really liked about it, because in ZBrush once you create an object (or a stroke) you can't manipulate or modify it in any way after you have "released" it. If you have many objects in your scene, you can select any of them in the Object List and then make the changes you want.
Being a sculpting program, Mudbox has a limited toolset (basically a few pushing and pulling tools). Nevertheless, this is not so bad since the tools can be modified with patterns, known as stencils or stamps, to create a variety of effects. A stencil is similar to a "brush," where the effect is replicated on every stroke, while a stamp creates a projected texture that deforms the objects using the direction normal to the camera view (this means that the object's "normal angle" will affect how the texture falls onto the object). The stencil works directly on the surface's normal, while the stamp works as a "projected image".
There is a tool that lets you draw curves, and you can use them as guides for your strokes. If you create the curve and turn on the "snap to curve" option, your brush will stick to that curve (given a certain tolerance). You can then paint along that guide curve.
Mudbox doesn't have a built-in renderer, so you can't view a "smooth refined version" of your work. I have to admit that at first it surprised me with the lack of a renderer, but the camera view quality is good enough to let you know how the final model wll look. After all, Mudbox is a sculpting tool, not a fully integrated 3D program.
One of the things people will be most interested in will be how well Mudbox plays with other software. In my case, I had to try Mudbox and Maya, so I imported a model that I was working on, and then I painted a lot of different effects on top of it. I would then try to export those bulges and deformations as a displacement map that I would bring back into Maya. The image below shows my original model and the displaced model side-by-side.
The original model is a few hundred polygons, while the displaced version has a little over 400 thousand. I took the screenshot using wireframe view so you can see how dense the subdivided model was. I then used Mudbox's "texture baker" to create a displacement map. The documentation is still somewhat poor, so I had to try different settings until I got the results I wanted. The issue with the documentation will be solved soon, as they are still working on it. However, there are no plans for downloadable documentation, so you have to view it online.
The next image shows the baker options. These are the settings that I stuck with after a few trials.
I created a 32 bit displacment map (and no normal map), and then I imported that into Maya. Luckily, there's a "settings" drop-down list for the last settings (the ones I couldn't understand, so I just selected the "Maya" preset) and then moved on to create the map (there are no presets for Max, XSI and such yet). As a final step, I applied that displacement map to my model inside Maya, and after a couple of minutes I had my render.
If you visit the Mudbox website, you can see the gallery where there are some models created exclusively with Mudbox. On the other hand, many people use these kinds of programs just as finishing tools for their models. Either way, Mudbox will prove to be a very useful tool in your work.
Be sure to check out the following links:
All supporting images are copyright, and cannot be
Animation Alley is a regular featured column with Renderosity Staff Columnist Sergio Rosa [nemirc]. Sergio discusses on computer graphics software, animation techniques, and technology. He also hosts interviews with professionals in the animation and cinematography fields.