Đang chuẩn bị liên kết để tải về tài liệu:
Advanced Maya Texturing and Lighting- P15

Advanced Maya Texturing and Lighting- P15: I should stress that I am self-taught. In 1994, I sat down at a spare seat of Alias PowerAnimator 5.1 and started hacking away. After several years and various trials by fire, 3D became a livelihood, a love, and an obsession. Along the way, I was fortunate enough to work with many talented artists at Buena Vista Visual Effects and Pacific Data Images. In 2000, I switched from PowerAnimator to Maya and have since logged tens of thousands of hours with the subject of this book | Transparency value of the Maya material must be increased for the volume material to be seen. Mib_volume is an extremely simple fog that carries two attributes Color and Max. Color represents the color of the fog and Max controls the density. A Max value of 0 will equal 100 percent density. A Max value greater than 8 will create close to 0 percent density. Parti_volume is a more advanced material that supplies additional attributes to control light scattering and nonuniformity. Note Volume materials and effects often refer to the replication of participating media. Participating media are any media that scatter light. This would include fog clouds smoke ocean water and so on. Preparing mental ray Shaders for Global Illumination If a mental ray shader is used with Global Illumination or caustics it will be ignored by the photon tracing process unless a connection is made to the Photon Shader attribute of the shading group to which the shader belongs. Maya 8.5 and Maya 2008 treat this necessity in slightly different ways. With version 2008 some mental ray shaders such as Dgs_material and Transmat are automatically connected to both the Material Shader and Photon Shader attributes of a shading group node when they are created. Other shaders such as those with the Mib prefix are only connected to the Material Shader. With version 8.5 all shaders are connected to the Material Shader attribute leaving Photon Shader open. In fact mental ray provides four sister photonic shaders that may be used in this situation Dgs_material_photon Dielectric_material_photon Transmat_photon and Parti_volume_photon. Each corresponds directly to its material or volumetric material namesake. For example if you want to photon trace with Dielectric_material you can map Dielectric_material_photon to the Photon Shader attribute of the shading group node see Figure 12.21 . Dgs_material_photon Dielectric_material_photon and Transmat_photon are located in the Photonic Materials section of the .