Rendering with mental ray and 3ds Max Figure 4.13 Brightentheintensityandenablethelight-castingcapabilityofthematerial. light on the sign in front of them (see Figure 4.13). Remember that you must render with final gather for the material to actually cast light. 5. Close all windows and dialogs and save the file. A self-illuminated material that casts light is not a substitute for a photometric light that you would use for real headlights, but is used to simulate the dull glow of a very diffuse light. Self-illuminated Arch & Design materials can make your scenes more convincing when used on soft glowing light sources like TV screens or computer monitors, neon lighting, even glowing lights on the front of a com- puter panel. Enabling the material to cast a diffuse light adds an extra dimension to the effect without being a large drag on productivity. 4.2.4 Cutoutmaps Standard materials rendered with the scanline renderer in 3ds Max have always been able to use maps in the Opacity slot to create the illusion of transparency. White pixels in the map are opaque, black pixels are transpar- ent, and gray pixels are somewhere in between. In mental ray, Arch & Design materials maps can still be used to create the illusion of transparency, but the maps are now placed in a slot called Cutout. The concept is similar where black pixels "cut out" the surface of the object, and gray to white pixels vary from semitransparent to opaque. In the next exercise you will learn to use an existing map in the hot rod scene. You will create the bump maps on the side of the truck and around the doors to simulate a pipe-framed open vehicle instead of the solid body truck you've used in previous exercises. 4.2.4.1 Exercise:Cutoutmapsfortransparency 1. Open the file called Ch04_cutout_01.max from the CD-ROM and save it to your hard drive with the name Ch04_cutout_02.max. Render the Camera01 viewport to see the hot rod that has bump maps applied to the side to create raised areas (see Figure 4.14). 2. Open the Material Editor and make sure that Body material is highlighted; top row, second from left sample window. In the Special Purpose Maps rollout, you'll see the map listed in the Bump slot that creates the 84