WARNING Deleting an effect from a light doesn’t remove it from the scene, even though you may have created it through the light. The effect and its settings are still in the Environment or Effects dialog boxes accessed from the Rendering menu.

Selecting the effect and clicking the Setup button brings up its respective dialog box (ordinarily accessible through the Rendering menu) so that you can adjust the settings of the effect.

Simulating Light and Color in 2D

3D computer graphics are not actually 3D. We’re rendering to a 2D arrangement of pixels of different colors. That’s it. All the magic of 3D does is calculate the necessary colors and values of the pixels to simulate reality with all its qualities of light and shading, based on instructions we give the program. We give the program this information through an interface that responds to us as if we were in a three-dimensional world, and the program stores information about all three dimensions in the file. Yet every interaction we have with our file is through a flat 2D image on the computer screen—during the work in our scene as well as in our final rendering.

Since our output is still a 2D representation of 3D realities, we are striving for the same goal as the old masters of painting: rendering three dimensions in two. Despite the fact that our methods are so different, the techniques of these masters still apply. These techniques are actually used behind the scenes when 3D software is written. Shaders, for example, calculate how to shade an object based on the angle of the CG light hitting the object; the information on how to do this comes from centuries of cultural experience in drawing and painting. By the same token, the way a 3D program calculates the rendering of objects at a distance is based on theories about perspective used in Western culture since the Renaissance. It’s useful to remember that the conventions of rendering are culturally influenced, and that MAX approximates these rules through intensive calculations that you never see.

Computers can only simulate an illusion of reality, and they do so by calculating approximations of our abstract theories and models of reality. 3D applications have to simplify these approximations. If every ray of light that you would really see were calculated, you would never be able to render a single object. Lighting in the real world is almost infinitely complex. Understanding how artists have rendered 3D realities in 2D images can help you add back what might be lost in approximation. For example, a 3D application will not directly calculate aerial perspective, but by knowing about it, you can add it to a 3D scene. What follows might be considered a “crash” art course in using color and shading to achieve the illusion of depth in 2D images.

Simulating Aerial Perspective

When looking at a landscape in the real world, we see the colors of objects as paler and more blue the farther away they are from us. Blue light is scattered by the moisture and particles in the air of the intervening atmosphere. You can test this by looking at a photograph of a landscape.

1.  Reset MAX.

2.  Open the Asset Manager (Utilities Ø Asset Manager).

3.  Select the \Maps\Backgrounds directory in the left pane of the manager.

4.  Double-click the LAKE_MT.jpg image (Figure 10.7) in the right pane.

FIGURE 10.7  Test the atmosphere in this lake scene.

5.  Right-click the image to bring up the eyedropper tool. Drag the eyedropper around the image and watch the red, green, and blue values change. Notice that the blue value increases toward the background.

The colors of the farthest background are lighter and shifted toward blue, because you are looking through more of the atmosphere. Landscape painters make use of this property by painting the farthest mountains a paler, bluer color than the next layer closer to the foreground. This effect can be simulated in MAX by adding a bluish fog to a scene. Another way is to use a Blend material. Let’s try it.

	NOTE The scene used in this exercise takes a long time to render. Be patient.

	4. Open the Material Editor and select the empty light purple material slot next to the Greenery Blend material. Change the name of this material to Purple Fog.
	5. Drag the Diffuse color swatch of the Purple Fog material to the Ambient color swatch and choose Copy. With the Color Selector, make the Ambient color a much deeper version of the diffuse purple.
	6. In the Diffuse channel, add a noise map with the following settings in the Noise Parameters rollout: check Regular under Noise Type; and set Size to 23, High Threshold to 1.0, and Low Threshold to 0.35.
	7. Click the Go To Parent button. In the Maps rollout of the parent material, set the strength of the Diffuse channel to 30.
	8. At the top level of the material, click the Type button and choose Blend. Check Keep Old Material as Sub-Material. Name this new material Distance Blend.
	9. Drag the Greenery Blend material into the second material slot on the new blend material and check Instance.
	10. Click the Mask button of the Distance Blend material and choose a Gradient map.
	11. In the Gradient Parameters rollout, drag the black swatch to the white and click the Swap button.
	12. Set the Color #2 Position to 0.75.

	13. Go back to the Distance Blend material parent level and check Use Curve. Set the upper transition zone to 0.87 and the lower transition zone to 0.38.
	14. On the Main Toolbar, click the Select by Name tool, highlight Hills01 and Hills02, and click the Select button.
	15.In the Material Editor, with our Distance Blend material still selected, click the Assign Ma terial to Selection button.
	16. Press Shift+E to render again with your most recent settings. At first it may appear to be rather harsh, but give it a lot of time to finish rendering. The hills fall off in the distance. We wi also be working on this scene in the next exercise to alter the light and shadow colors.

© 2000, Frol (selection, edition, publication)