Pixar’s RenderMan renderer is used to render all of Pixar’s films and by many film studios to render visual effects for live-action movies. RenderMan started as a scanline renderer based on the Reyes algorithm, and it was extended over the years with ray tracing and several global illumination algorithms. This article describes the modern version of RenderMan, a new architecture for an extensible and programmable path tracer with many features that are essential to handle the fiercely complex scenes in movie production. Users can write their own materials using a bxdf interface and their own light transport algorithms using an integrator interface—or they can use the materials and light transport algorithms provided with RenderMan. Complex geometry and textures are handled with efficient multi-resolution representations, with resolution chosen using path differentials. We trace rays and shade ray hit points in medium-sized groups, which provides the benefits of SIMD execution without excessive memory overhead or data streaming. The path-tracing architecture handles surface, subsurface, and volume scattering. We show examples of the use of path tracing, bidirectional path tracing, VCM, and UPBP light transport algorithms. We also describe our progressive rendering for interactive use and our adaptation of denoising techniques.

Spatially-tiled architectures, such as Coarse-Grained Reconfigurable Arrays (CGRAs), are powerful architectures for accelerating applications in the digital-signal processing, embedded, and scientific computing domains. In contrast to Field-Programmable Gate Arrays (FPGAs), another common accelerator, they typically time-multiplex their processing elements and are word rather than bit-oriented. These differences lead us to re-examine some of the traditional architecture choices made for FPGAs as we move to these coarser-granularity architectures. In this paper we study the efficiency of time-multiplexing global interconnect as architectures scale from single-bit to multi-bit datapaths.Using the Mosaic infrastructure, we analyzed the design trade-offs involved in static vs. time-multiplexed routing for global interconnect channels, as well as the benefit of including a dedicated bit-wide control interconnect to supplement the word-wide datapath of a CGRA. We show that a time-multiplexed interconnect is beneficial in these coarsegrained systems, reducing the area-energy product to 0.32× the area-energy product of a fully static interconnect. We also show that for our benchmarks, which include single-bit control logic, providing both word and bit-wide interconnect resources further reduces the area-energy product to 0.94× that of an exclusively word-wide interconnect.

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