Inspired 3D: Lighting and Compositing: Lighting a Production Shot
Testing Key-Light Positions CG Light Choice
Because the lighting for shot SF-02 needs to work well with shots SF-01 and SF-03, key-light test s on frames from those shots are helpful as well (see Figures 6 and 7). In Figure 6, the key-light is fairly low and in front of the character. This position most closely simulates the desk lamp, but using the key-light from a low angle such as this results in a frightening looking character. Lighting from low angles is commonly used in horror films, but the goal is not to create a demonically possessed CG artist. Because most people are seen with lighting from above, whether it is from the sun or a light fixture, the unusual shadows cast by lighting from below cause the character to look otherworldly. The key-light positioning in Figure 7 offers a more flattering look for the character.
The key-light is a spotlight with no color adjustments at this point. The cone angle is wide enough to extend beyond the view of the camera, and the edges are softened using a value of 20 in the penumbra field. Each person develop s his own techniques and preferences for choosing light s and placing them in a scene. There are no hard fast rules in this process, because the final image is judged and not the CG lighting setup. The examples shown here use only spotlight s because of their versatility and the level of control they offer. The key-light in each of these scenes uses depth-map shadows with a 2K resolution. This is a fairly high-resolution size for shadow maps, which help s reduce artifact s apparent in self-shadowing situations. Figure 8 is a detail view from a frame of shot SF-01 showing the key-light shadow from the characters left arm casting onto his body. In the top image, the depth map shadows are rendered at a resolution of 512 pixels square, and in the bottom image they are increased to 2,048 pixels square. The top image shows artifacting in the shadow s edges, while the increased shadow map resolution in the image on the bottom has smoothed the shadows edges considerably.
Testing Key-Light Positions
CG Light Choice