Features

Iguana is a global illumination rendering engine for Maya, but it's not a product (not yet, at least). That's why it's free. And that's why I would really like that you, people, downloaded it and used it in any way you like. Even in production, if you feel so. Iguana is still lacking some important things, motion blur for instance, but I feel it can be effectively used anyway.

What Iguana has that Maya's renderer hasn't:

- global illumination, the radiosity way: no caustics, however;

- a new kind of light, called "surface light": essentially, for Iguana any object can become a light source. This can be used to simulate the illumination of the sky, for instance;

- blurry reflections (and refractions);

- support for HDRI maps and image based lighting;

- New with v. 1.5: interactivity. For sure, the most important among the new features of Iguana. When Iguana runs interactively, you see a small render window staying atop of Maya, and everything you do in the scene is immediately reflected into it.

What Iguana doesn't do:

- motion blur;

- particles and light effects, like glow for instance;

- Paint Effects (but you can always convert Paint Effects strokes into polygons...);

- depth of field.

All the rest is supported, with some limitations. Iguana does raytracing, and it implements the most used shading models, like Lambert, Phong and Blinn. Layered shaders are supported, too. Of course, you can use textures, images and procedural ones, and you can use shading networks too.
Iguana runs on Windows and Linux. It is multithreaded, so if you have more than one processor on your machine you can use all of them to render. It doesn't support network rendering (that is, it's not possible to use more than one machine to render a single frame), but it will in the future. Iguana reads Maya scenes directly, without having to translate them in any way, and you don't need any special editor for materials or for anything else - you do everything with Maya, then you render in the Render View or as a batch render. Simple.

What kind of global illumination is it?

The global illumination problem can be approached in two ways: the first is photon mapping (like Mental Ray), the second is radiosity. Photon mapping has always been the most popular way in commercial renderers, partly because it's simpler to implement, partly because it's faster. But it does cause a lot of problems, too - noise and flickering, especially in animations. Iguana was originally meant to be a photon mapper, but when I came to those problems I decided to start over and go the other way: radiosity. Radiosity is notoriously an ugly beast, but I introduced some means that make the problem tractable and easy to deal with. And I actually believe that with Iguana things can't be any simpler.

How does Iguana work?

In a radiosity scenario, all the objects are considered as potential emitters of luminous energy. That is, it's like the scene is lit by the light sources AND by the objects of the scene itself, because when an object receives light it also emits some diffusely, like in the real world. In the real world, in a room for instance, light comes from light emitters and gets diffused in the environment by the walls, by the floor, by the ceiling and by all the objects in the room. This is what Iguana tries to emulate: the scene is lit not only by light sources directly, but also by parts of the scene itself indirectly.

When Iguana renders, it tesselates the geometric objects, then it starts calculating the global radiance of the scene (if you chose to, of course). Then it begins rendering the scene, starting from the center of the image and spiralling towards the borders. The final image is the sum of different components, that can be saved separately along with the main image: these components are the direct one (it's the contribute to the illumination coming directly from the lights), the specular one (the reflections and/or refractions on specular objects) and the indirect one (it's the contribute to the illumination coming from the diffusion of luminous energy in the scene, that is from diffuse illumination). As an example, below you can see an image and its different components:

In every object in the scene Iguana looks for specific attributes, specific to Iguana, that tell it what to do and how to do it. For instance, if Iguana has to calculate the radiance of a scene, it has to know for every object if it emits diffuse illumination or not, or if it receives any. How are these attributes added to the objects in the scene? They are automatically added by the plugin, that does all the job for you. Of course, Iguana looks for other attributes as well, tesselation-related attributes for instance. You can have details for all of this in the tutorials and in the documentation that you can find in the download section.

What's in this distribution (v. 1.5)?

The software is all made up by an installer on Windows, and a TGZ archive file on Linux (on Linux there's no installer, you have to do all by hand... but it's very easy, don't worry). The files that get installed are a plugin, some executables and some MEL scripts.

OK I like all this, how do I get started with Iguana v. 1.5?

Simple - go to the download section, there you will find the software for your platform, Windows or Linux, and the documentation together with the tutorials: these are by far the simplest way to learn to use Iguana, and the most recommended. They are very straightforward, quite short, and not difficult at all.