Review: Next Limit’s Maxwell Render
By: George Maestri
Issue: Volume: 33 Issue: 2 (Feb. 2010)

Review: Next Limit’s Maxwell Render

Maxwell Render
Creating realistic images has always been one of the main goals of  3D computer graphics. Special effects artists, architects, and many others are in the business of simulating reality using 3D tools. However, no matter how realistic the models and textures in a 3D scene, the scene must be rendered. Like photography, rendering is an art that uses light to create an image. In 3D, however, light is calculated, and calculations can only simulate reality. Getting these calculations more correct is what makes one render look more “real” than another. Next Limit’s Maxwell Render is next in line for the throne of most realistic renderer.

The Maxwell Studio interface is clean and well organized, but many users will opt for one of the many plug-ins offered that allow rendering directly from standard CAD and 3D apps.

Maxwell Render is presumably named after James Clerk Maxwell, the famous physicist who discovered many of the equations for how light and electromagnetic waves propagate. It’s certainly an appropriate name for a renderer promising to be physically correct and capable of simulating light exactly as it behaves in the real world. The software is from Next Limit, which also makes the highly regarded RealFlow fluids and dynamics system—another piece of software that does a great job at simulating reality.

Maxwell Render can be used in two different ways. The first is to use Maxwell Studio, which is a master application that gives you the ability to author materials, set up cameras, and render scenes imported from other applications. This app has a nice interface that is reminiscent of the venerable Flint and Flame compositing applications from Autodesk in that the color scheme is rather dark and the interface elements not flashy, just functional. Most of the work is done in one or more 3D viewports. Lights, cameras, and objects can be added or imported from a number of 3D formats. For RealFlow users, simulations can be imported, as well.  

While Maxwell Studio is nice, I suspect most people will probably select the second option and use it as a plug-in to a more traditional 3D application. Maxwell Render plugs into a large number of applications, from 3D software such as 3ds Max and Maya (Autodesk) and LightWave (NewTek), to CAD applications such as SolidWorks (Dassault), Rhino (McNeel North America), and Sketchup (Google). I tested it in Maya, Max, and Sketchup, and found slightly different results. Maya and Max are certainly more robust applications, so many (but not all) of the standard materials and lights translate to Maxwell. Rendering can be started from the standard render options within each package. Sketchup doesn’t really have a render button, so rendering is started by exporting a Maxwell file, which automatically starts up a render window.
Maxwell Render comes with a good library of materials, and there’s a lot more that can be downloaded from the Web site. You can also author your own materials within your 3D application or Maxwell Studio. Maxwell Render’s materials are physically correct and work in a layered paradigm. A car paint material might have three or four different layers, for example—one for the base coat, one for the metal flakes, another for the topcoat, and yet another for the clear coat. Each layer can have wildly different parameters for very interesting effects. Individual layers can have the usual transparency and color channels, but also advanced features such as subsurface scattering.   
When applying materials within Maxwell Studio, you can add them on a per-object basis or by polygon selection. One thing I found was that the poly selection tools were not very robust, which made selecting discrete parts of the model more difficult. This shortcoming is one more reason to use Maxwell Render as a plug-in, so you can use the superior texture application tools found in 3D packages such as Maya.

The way Maxwell handles lights is interesting. When I opened Maxwell Studio, one of the first things I looked for was a way to add lights to the scene. There are no traditional spots or point lights within Maxwell Studio; the brightness of the materials is what creates light in the scene. For those who are using Maxwell as a plug-in to another application, however, the standard lights will translate, but internally Maxwell Render is seeing them as illuminated geometry. This lighting model opens up some new possibilities. If you want a fluorescent tube light, for example, you could model a tube and then add an illuminated material. Model that material into a shape, and you have a very realistic neon sign.

Maxwell Render is great at creating natural light, as evident in this image.

Maxwell Render also has built-in environmental lighting, such as skies for outdoor scenes. These can be configured with realistic parameters, such as the amount of ozone or water in the atmosphere, as well as its turbidity. Additionally, Maxwell Render has the ability to create HDRI-based lighting to match existing footage.

Cameras in Maxwell Render are very close to real-world cameras. Parameters such as f-stop and the type of diaphragm on the camera shutter make for highly realistic lens effects. You can even do tilt-shift effects with the camera to simulate advanced lenses used in architectural and product photography that correct for perspective distortion.

Once everything is set up, you can start rendering. Rendering can happen a frame at a time within a render window; it can also happen using a command line or in a batch render. The render window has some unique options. One of the things I really liked was the ability to set a specific time for each render. You could tell Maxwell to take one minute to render a frame or up to 30 minutes. The more time you give Maxwell, the better the image, but you can also speed up a render for testing or to get things out the door. Maxwell Render also lets you adjust the exposure during the render, or even after the render has finished. There’s also a feature called MultiLight, which lets you change the intensity of lights after the scene is rendered. The nice thing is that the results are full-quality, which certainly tops many other interactive renderers.

Of course, the final quality of the renders is what really matters. I found the images in Maxwell Render to be about as real as I’ve ever rendered anything. The nice thing about Maxwell Render is that it’s fairly easy to use. I didn’t have to figure out obscure values, such as photon energies or global illumination parameters; I just added light to the scenes, set up and adjusted the camera, then rendered. It was almost analogous to real-world lighting and photography. I would highly recommend Maxwell Render for anyone needing high-resolution, highly realistic renders.