Learn core principles of the Arnold render engine.
- [Instructor] Let's take a look at some core concepts in Arnold rendering. In contract to mental ray in earlier versions of 3ds Max, Arnold is primarily a physically-based renderer. This means it uses physical properties for lighting and materials. The parameters and work flows of physically-based rendering are slightly different from the traditional ones. You'll need to learn these new methods, but it's worth it because you get a more accurate simulation of materials and lighting, and ultimately you achieve greater realism with less effort.
To use Arnold most effectively, we should know a little bit about the algorithm that does the computations under the hood, as it were. Arnold is, what is known as a brute force algorithm and in fact, the Arnold renderer is named after famous body builder and politician, Arnold Schwarzenegger. So it's a nod to the power of brute force approach and brute force in rendering, simply means that the global illumination is being calculated on every pixel of the frame.
And this is in contrast to techniques such as final gathering or irradiance mapping in which there is a sub sampling of each pixel. In other words, we're not calculating GI in every pixel using those methods. So brute force is going to be slower because it's doing more work. The beauty of the Arnold renderer is that it's an optimized brute force algorithm. It's much faster than similar renderers, such as, for example, Autodesk Raytracer or ART.
Arnold is an unbiased renderer. This means that no mathematical or statistical trickery has been introduced into the render process in order to speed up the render times. By contrast Mental Ray is a biased renderer. And the distinction is really sort of a philosophical one because either biased or unbiased renderers can achieve a photo real result. But Arnold has taken the path of unbiased and that means it's more true to nature, as it were, but that may come at a cost of longer render times.
Arnold falls into a specific category of renderers called a Monte Carlo path tracer. This is a method in which rays are randomly fired out from each surface and that's what gives Arnold and other renderers of its kind the characteristic grainy look. It's also a method that provides fast interactivity in the active shade window in 3ds Max. Once again, Arnold is physically-based and it's set up by default to conserve energy.
In other words, it's really a simulation of how light dissipates in a scene. All Arnold lights are set up to obey a quadratic decay by default, meaning that they observe the inverse square law of how energy dissipates over area. To optimize that simulation, we have lots of control over the accuracy of the computations, either globally or through each individual light or material, we can control the sampling, which is the fidelity, and also the ray depth, which is the number of bounces for each one of the components in the simulation.
We can easily dial these controls up or down to control the look of the shot and to optimize render times. Although Arnold defaults to a physically accurate lighting simulation, we have the artistic freedom to achieve any non-physical effects we want. For example, we can adjust the amount of bounce light or color bleed on a material to achieve non-physical results and those are some key concepts in Arnold rendering.
- Arnold rendering concepts
- Arnold lights such as quad, spot, and distant
- Modifying Arnold object properties
- Filtering light with the gobo filter modifier
- Image-based lighting with Skydome
- Daylight simulation with Physical Sky
- Arnold Standard Surface material parameters
- Diffuse, opacity, and bump mapping
- Rendering refractions with Transmission
- Building an Arnold shading network
- Test rendering with utility map
- Mesh subdivision and displacement at render time
- Atmospheric perspective with scene environment fog
- Rendering a spherical environment with VR Camera