3ds Max 2012 Bible - Kelly L. Murdock [497]
FIGURE 47.12
The Indirect Illumination panel includes settings for caustics, GI, and Final Gather.
The Final Gather rollout is split into two parts. The top part features a set of Basic settings with several Presets that take the guesswork out of the settings. Simply choose one of the presets from the drop-down list, and all the key settings are automatically made for you. The preset options include Draft, Low, Medium, High, and Very High. The Multiplier and color swatch changes the intensity and color of the indirect light. The Weight value sets how much indirect light affects the Final Gather solution.
For caustics and for global illumination, the Maximum Number of Photons per Sample value determines how the caustic photons are blended. A higher value results in more blending and softer edges. The Maximum Sampling Radius value sets the size of each photon. This value is set automatically depending on the size of the scene. However, you can enable the Radius value and enter a new value manually.
The Volumes setting is used by Volume material shaders to set the photon's size. The Trace Depth settings determine the maximum number of reflections and refractions that a photon can take before it is ignored.
Photon and Final Gather maps can take a while to generate for a complicated scene, but once computed, they can be saved and reloaded. These files are saved using the .pmap and .fgm extensions. To generate a photon map, click the Generate Photon Map Now, or to generate a final gather map, click the Generate Final Gather Map Now button.
Final Gather sends out rays to a scene that has computed caustics and global illumination already and computes the light at that location. All these rays are then combined to produce a total lighting picture of the scene and then blended to help fix any lighting abnormalities that may exist in the scene. The Samples value determines how many rays are cast into the scene. The Final Gather lighting pass can then be saved to a file after it is computed.
Rendering control
The core rendering settings for the mental ray renderer are contained within the Renderer panel of the Render Scene dialog box, shown in Figure 47.13. Using these settings, you can increase the speed of the renderer (at the expense of image quality).
FIGURE 47.13
The Renderer panel includes several rollouts of settings for controlling the mental ray renderer.
The Sampling settings are used to apply an anti-aliasing pass to the rendered image. These samples can be filtered, and you can control the details of the contrast between the samples. The Bucket Width is the size of the blocks that are identified and rendered. Smaller buckets do not take as long to render and provide quicker feedback in the Render window.
The mental ray renderer uses several different algorithms, and you can specify which ones to ignore in order to speed up the rendering cycle in the Rendering Algorithms rollout. If a needed algorithm is disabled, the features that rely on that algorithm are skipped. You can also set the Trace Depth for Reflections and Refractions and control the Raytrace Acceleration values.
When a preview render is rendered in the Rendered Frame Window while mental ray is enabled, an additional panel of options appears below the window as shown in Figure 47.14. The options on this panel let you quickly adjust the precision value for the Antialiasing, Soft Shadows, Final Gather Precision, Reflection, and Refraction settings. You also can speed the re-render by reusing the Geometry and Final Gather solutions if they haven't changed. The Render button lets you re-render the scene immediately.
Advanced mental ray
The mental ray renderer also includes many additional features that you can take advantage of, including Depth of Field, Motion Blur, Contours, Displacement, and Camera Shaders. The settings for these additional features are located in rollouts at the bottom of the Renderer panel. For