Although newer version of Maya have incorporated Solid Angle’s Arnold renderer. NVIDIA’s (formerly mental images) mental ray is still used in production quality rendering. People coming from Maya’s basic shader e.g. Phong, Blinn, Lambert don’t get daunted watching the mental ray shaders. So today I’ll explain what they actually mean. mental ray materials in Maya **mi - **mi is short for mental images, the facility in which mental ray was developed.