• 2 Iray principles

2 Iray principles

Car model: Sven Prochnow | Rendering and post-production: [zerone] | Photographer: Markus Esser
The performance of a renderer such as Iray is relatively independent of how complex the scene geometry is. The complexity of light paths is more important: A candle in a labyrinth, or light rays diverging from a narrow window, will take longer to yield a good-quality rendering than light shining through a broad skylight or picture windows. As with other renderers, performance is also proportional to the resolution of the rendered image. The complexity of materials in the scene also affects performance: The more textures, blending, and noise a material has, the longer it takes to calculate the results.
Iray is physically based and simulates light paths as close as possible to reality. This is the reason why you have to act in specific situations different than in other renderers like mental ray. To give an example: It is not possible to turn off shadows for specific geometry.
Iray for Maya 2.0 offers two render modes: Iray Photoreal and Iray Interactive. Iray Photoreal is exactly the render mode users are familiar with from older Iray for Maya versions. It is an interactive, ray-tracing based render mode that generates "push-button" photorealistic imagery featuring complex global illumination effects. Iray Photoreal makes use of a highly optimized BSDF and EDF based framework, essentially capturing the physical behaviour of real-world materials and light sources. Iray Photoreal can leverage NVIDIA CUDA capable GPUs to render photorealistic images much faster than on a CPU, due to the highly parallel nature of the underlying simulation processes. If a system does not feature CUDA capable graphics boards it will automatically fall back to using only CPU based rendering. This will produce the same images but typically the rendering will take longer to complete. In addition, it can also use both resources at the same time.
Iray Interactive is an interactive raytracing render mode which uses faster yet less accurate rendering algorithms than Iray Photoreal. Iray Interactive targets a look which is consistent with the physically-based result of Iray Photoreal, yet it is optimized for interactive scene manipulations. Iray Interactive leverages NVIDIA CUDA-capable GPUs. It is ideal where ray-tracing effects, such as reflections and refraction, are desired and limited photorealism is acceptable.