Issue: Volume: 25 Issue: 6 (June 2002)

Entropy 3.1

By George Maestri

Exluna is a new company on the graphics scene, but many of its principals have a long history in the industry. Some of Exluna's engineers are from Pixar, including Larry Gritz, who also developed BMRT (Blue Moon Rendering Tools), a popular, free raytracing program. It's no wonder that the company's first product is a renderer. (There has in fact been legal action between Pixar and Exluna. See pg. 12.) Entropy is a RenderMan-compliant program that offers high quality and a number of advanced features. And, Exluna has gone out of its way to make the program easy to use.

The software is licensed on a per-machine basis. It runs on a number of platforms, including Linux, SGI/Irix, and Windows NT/2000. On Irix and Linux, it operates as a standalone renderer, and can be run from a command line, which allows it to be integrated with existing rendering pipelines without too much hassle. On Windows NT/2000, the software can be run from the command line, but also from within Discreet's 3ds max modeling and animation program. Plug-ins for other major 3D applications are planned.

When I first began testing the software with 3ds max and the Exluna plug-in, my instinct was to play around without looking at the manual. I immediately no ticed that Entropy adds a new material that lets you use Ren derMan shaders directly within max, and that Exluna bundles a number of sample shaders along with the software. The ability to develop your own shaders adds a lot of power and flexibility, but writing RenderMan shaders from scratch is not for the timid.
This character was created using Entropy's displacement mapping atop a blobby surface, for a realistic clay look.

A quick browse of the help files revealed a much simpler way to use Entropy, which is to create materials directly within max's materials editor. Entropy automatically compiles the stock max materials into RIB files whenever a render is run. This essentially eliminates the learning curve, and allows max users to create and apply textures exactly the way they always have. When Entropy is set as the renderer, max's standard lights, cameras, and materials also get a few extra rollouts containing those Entropy parameters not supported by the standard max interface.

The software supports all the max shaders and materials, with a few minor exceptions (such as Combustion, Perlin Marble, and Particle Age.) Exluna has announced its intention to provide support for all native max materials as well as all third party materials in a future release. I'd love to see some of the popular Blur materials as part of the short list.

No matter how good the integration, the software still needs to render high quality images in order to be useful, and Entropy's results are excellent. The renderer gives a natural look to the images it creates. Entropy supports unlimited bit depths, making it ideal for feature film work. It also can utilize deep file formats such as RLA, which can contain additional data such as G-buffer information.

Entropy has a number of advanced features. The software supports user-definable antialiasing to further customize the look of the renders. One of my favorite features was the true displacement mapping, which is of excellent quality. Similar to bump mapping, it allows you to create the illusion of complex geometry without the overhead.

Advanced lighting features include caus tics and global illumination. An additional lighting feature is the ability to define any geometric object as a true area light, which makes possible soft and natural lighting, such as that on an overcast day.

Effects include the ability to calculate depth of field and motion blur. Depth of field is based on a real-world camera analogy, where users input basic camera parameters, such as focal length and f-stop and target distance. Motion blur is calculated on a per-object basis. Results for both effects were excellent.

As for speed, render times were not as fast as with other software, but they were acceptable. As with any renderer, adding effects such as raytracing, caustics, and global illumination slows render times.

I ran some quick tests using Entropy against max's scanline renderer. A simple scene with three objects, two spotlights, and no shadows took two seconds per frame using max, and 18 seconds per frame using Entropy. The stock max file apollo.max took 14 seconds per frame using max, and 5:24 seconds per frame with Entropy.

Overall, Entropy is an excellent renderer. Its tight integration with max makes it an obvious choice for studios doing high-end production work.

George Maestri is a writer and animator living in Los Angeles.


Entropy 3.1
Price: $2250 with support; $1750 without support
Minimum System Requirements: 450MHz Intel, AMD, or compatible processor running Windows 98/NT/2000/XP or Linux; SGI processor running Irix 6.5;
128MB of RAM
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