Render Elements
The compositor's bread-and-butter production task is color correcting and balancing. For 3D art to integrate into a scene, much subtle tweaking must be done. Being able to control the final look of the rendering in 2D form is, in many cases, not enough. Even in "real life," a shot in Star Trek of the USS Enterprise in orbit over a planet would have to be shot many times, in different lighting, and the final shot would be a composite of the various camera passes.We don't have to do anything so complex in 3ds max 7. A simple visit to the Render Elements panel in the Render Scene dialog can get us fixed up in no time (Figure 21.2).Figure 21.2. The Render Elements panel of the Render Scene Dialog.
 As you can see in Figure 21.2, all the available components of the picture have been broken out into separate files. A compositor might use these to cut out the objects in the scene, to adjust the shadow color so as to fit in with the rest of the composite, and to get the specular highlights to really zing.Next follows a brief explanation of the file types that you can render separately. First, look at Figure 21.3, the full rendering of the still-life. Time to render a 1280-by-960 picture using the Default Scanline Renderer: 18 minutes, 3 seconds on a 2.53 GHz machine with 1 GB of RAM.Figure 21.3. The still-life rendering. (stillLife.jpg on the DVD)
 By clicking the Add button, you can specify the additional output files that will be created when you render (Figures 21.4 to 21.18). Each one may be turned on and off in the Selected Element Parameters area, and the individual file location set. We have the ability to write a combustion file (see below). Finally, if there are additional parameters to be set, a rollout will appear at the bottom.Figure 21.4. Specular: The specular element of the rendering.
 Figure 21.18. Matte: Renders a matte mask, based on Effect or Object IDs, or G-Buffer channels, or selected objects. An excellent way to cut out a mask for individual objects or materials. In the rendering, the crystal ball was given an Object ID of 2.
 Note | You may have to scroll down in the panel to see the rollout area. It's context-sensitive, so that the appropriate info comes up when a particular Element is chosen by clicking it. |
Figure 21.5. Diffuse: The diffuse element of the rendering. A rollout appears at the bottom of the Render Elements panel, allowing for the addition of lighting effects.
 Figure 21.6. Self-Illumination: The self-illumination element of the rendering: In this case, it's the lampshade and switch.
 Figure 21.7. Reflection: All the reflections in the rendering. Note that even the Ink 'n Paint material is reflected.
 Figure 21.8. Refraction: All the refractions in the rendering.
 Figure 21.9. Shadow: The shadows in the rendering. Black-and-white shadows are saved only in the alpha channel.
 Figure 21.10. Atmosphere: The atmospheric effects in the rendering. In this case, there were no effects, so the picture is black.
 Figure 21.11. Blend: A custom combination of elements. A rollout at the bottom of the Render Elements panel allows you to choose the elements you want. In this case, Specular and Self-Illumination were chosen.
 Figure 21.12. Z Depth: A grayscale representation of the depth of all objects within the scene. The nearest objects appear white or light gray, and the depth of the scene is black. It's important to set the proper Z Min and Z Max values to get the right shading. They are located in the Z Depth parameters rollout at the bottom of the Render Elements panel.
 Figure 21.13. Alpha: A grayscale representation of the alpha channel, or transparency, of the scene. Transparent pixels appear black, and opaque pixels white. Translucent pixels appear gray. The darker the pixel, the more transparent it is. This would help you to composite in an object flying through the sky.
 Note | Years ago, I came up with an analogy to help me remember which color denoted transparency. Imagine a brightly lit room with white walls, and a window looking out into the darkest night. The walls are solid, of course, and the black night air is transparent. The reverse of this (black solid walls and only white light) would be almost impossible to pull off. |
Figure 21.14. Background: The background of the scene. None of the Render Elements exports the Background, so this could be handy.
 Figure 21.15. Ink: The Ink component (borders) of Ink 'n Paint materials. Note that this was reversed, and the alpha channel used, as the Ink was represented by black.
 Figure 21.16. Paint: The Paint component (surfaces) of Ink 'n Paint materials.
 Figure 21.17. Lighting: The effect of lights and shadows in the scene. Great for changing the gamma, or ratio of dark to light.
 It's kind of a hassle to write out all those different files, then load them up individually in your compositor. Render Elements has the ability to save all of them together as a combustion .cws file, with all of the channels ready to go (Figure 21.19).Figure 21.19. A full Render Elements composite as seen in discreet combustion 3.
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