Learn about the strengths and limitations of Arnold.
- [Instructor] Let's get acquainted with Arnold. We'll learn a little bit about our new friend and its strengths and limitations. Arnold is the default production renderer, so when you click render in Maya, Arnold is invoked. The old software renderer is still available, but it is no longer being developed, and it certainly doesn't have any of the advanced features that Arnold offers. As the new production renderer, Arnold replaces Mental Ray, but it's more than that, because in many ways, Arnold is an upgrade.
It has capabilities and ease of use that were lacking in legacy versions of Mental Ray. Invidia is still actively developing Mental Ray, and it is available as a Maya plugin with a licensing scheme similar to Arnold. The free versions of Arnold and Mental Ray allow interactive rendering on a single workstation. We'll talk more about that in a moment. Arnold is a software product developed by the Spanish company Solid Angle, and in 2016, Autodesk acquired Solid Angle, and now Arnold is finding its way into various Autodesk products.
Arnold has many strengths relative to competing renderers. You'll notice right away that Arnold excels at photorealism, and it is very fast, considering what it's doing, simulating the physics of light. Arnold is also flexible. You can achieve photorealistic results, or non-physical, impressionistic results, or anything in between. Arnold is very reliable and easy to use, and therefore it is a leader in the motion picture industry.
Arnold plugins have been developed for most of the major 3D graphics packages, and this means that once you learn Arnold, it's easy to use it in other programs. Arnold has a high degree of cross-application compatibility and, in some circumstances, can even be used to transfer shading networks between different programs. However, there are some limitations to Arnold, most notably, as of MtoA plugin version two, there is no full featured implementation of render to texture.
You can bake textures and lighting in Arnold, but it is very limited, and you're not able to do things like render out a diffuse and specular pass separately. So it's not terribly useful if you are an artist working in games and virtual worlds. If your shading network includes Arnold nodes, you can't bake those using a render to texture engine in competing software such as Mental Ray. With changes in the economics of the industry for 3D rendering software, we now see that there are some limitations in what we can do with the version of Arnold that ships with Maya, or the free download from Solid Angle.
Specifically, you cannot render in the background, known as batch rendering, you cannot render from the command line, and you cannot render on a network render farm. If you try to do any of those things, you'll get a watermark over your image. The only way to render without a watermark using the free Arnold plugin, is interactively within the Maya graphic user interface. So this licensing can be a problem if you're on a render farm, or simply need to render from the command line.
To remove the watermark, you'll need to rent a license from Solid Angle. And finally, the last significant limitation is in the Arnold core. Transmissive, or hard caustic effects, are not possible. In lighting, a caustic effect is light that's focused by a curved surface, either a specular reflection or refraction through a transparent material. Because Arnold does not currently include any form of photon mapping, you cannot expect transmissive or refractive caustics.
Arnold does calculate specular caustics, or light bouncing off a shiny surface, such as metal, but if you need transmissive caustics of light bending through a transparent material, you won't be able to achieve that effect in Arnold, but in all other areas, Arnold exceeds expectations, so hopefully we'll see caustics added in a future version. And that's an introduction to Arnold in Maya.
- Arnold rendering concepts
- Lighting with Maya and Arnold lights
- Controlling exposure
- Filtering light with Gobo
- Light attenuation with Decay
- Image-based lighting with Skydome
- Exterior daylight with Physical Sky
- Arnold Standard Surface material attributes
- Mapping material attributes
- Rendering refractions
- Mesh subdivision and displacement at render time
- Shading effects such as ambient occlusion and vertex color
- Camera effects such as fisheye and depth of field
- Animation image sequence rendering