Question: Which photorealistic rendering system was used in Tarsem Singh's directorial debut?

Context paragraphs:
Blue Moon Rendering Tools: Blue Moon Rendering Tools, or BMRT, was one of the most famous RenderMan-compliant photorealistic rendering systems and was a precursor to NVIDIA's Gelato renderer.  It was distributed as freeware.  BMRT was a popular renderer with students and other people who were trying to learn the RenderMan interface.  It also had some features PhotoRealistic RenderMan did not have at time, for example, ray tracing.  Even Pixar used BMRT for ray tracing before PRMan had such features.  According to Exluna, it was used for 3D rendering in movies such as "A Bug's Life", "Stuart Little", "The Cell", "Hollow Man", and "Woman on Top".

Brazil R/S: Brazil Rendering System was a proprietary commercial plugin for 3D Studio Max, Autodesk VIZ and Rhinoceros 3D.  Steve Blackmon and Scott Kirvan started developing Brazil R/S while working as the R&D team of Blur Studio, and formed the company SplutterFish to sell and market Brazil.  It was capable of photorealistic rendering using fast ray tracing and global illumination.

Element 3D: Element 3D is a third-party After Effects plugin developed by Video Copilot.  It is a 64-bit plugin that runs in both Windows and MacOS.  It is used for importing/creating 3d objects and for particle rendering.  It is mostly used for motion design and visual effects.  Element is capable of animating and rendering.  It uses OpenGL to generate images more quickly than CPU rendering is currently capable of.  The plugin features physically based shaders, texture mapping, lighting, animating and 3D compositing tools.  Although there are limitations to rendering in OpenGL compared to raytraced rendering, many workarounds are possible to help yield highly photorealistic results, especially if the workstation is equipped with a high end video card.  Element 3d is more limited in its ability to generate scenes from scratch than a full featured 3d program such as Cinema 4d.  However, professional results, especially with simple scenes such as logo fly-ins and animated typography can be achieved in a comparatively short time.  As with any 3d program, Element 3d has a learning curve.  While simple concepts are easy to achieve, photorealism requires patience, practice, experimentation, and a compatible OpenGL video card with at least 2 GB of VRAM.

Tarsem Singh: Tarsem Singh Dhandwar (Punjabi: ਤਰਸੇਮ ਸਿੰਘ ਧੰਦ੍ਵਾਰ ; born 26 May 1961), known professionally as Tarsem, is an Indian-American director who has worked on films, music videos, and commercials.

Specular International: Specular International was a company founded by Dennis Chen and Adam Lavine in 1990.  Specular created and distributed several software products, the most popular of which was Infini-D, an integrated 3D modeling, rendering, and animation software product that specialized in 3D effects such.  Infini-D was part of a larger trend in bringing 3D technologies once only available in powerful workstations to a wider personal computer audience.  Other Specular products included Collage, a high-resolution Adobe Photoshop compositing companion product, and BackBurner, a distributed rendering system that used multiple Apple Macintosh computers on a network or over the internet to render computationally intensive 3D animations.  Many Specular employees joined Adobe Systems, and worked on products including Adobe Photoshop, Adobe After Effects, and Adobe Premiere.  Specular merged with MetaTools in 1997 to form MetaCreations.

The Cell: The Cell is a 2000 American science fiction horror film directed by Tarsem Singh in his directorial debut, and starring Jennifer Lopez, Vince Vaughn, and Vincent D'Onofrio.  It received mixed reviews upon its release, with critics praising its visuals, direction, make-up, costumes and D'Onofrio's performance, while criticizing its "Silence of the Lambs"-inspired plot, an emphasis on style rather than substance, and masochistic imagery.

Reyes rendering: Reyes rendering is a computer software architecture used in 3D computer graphics to render photo-realistic images.  It was developed in the mid-1980s by Loren Carpenter and Robert L. Cook at Lucasfilm's Computer Graphics Research Group, which is now Pixar.  It was first used in 1982 to render images for the "Genesis effect" sequence in the movie "".  Pixar's RenderMan is one implementation of the Reyes algorithm.  According to the original paper describing the algorithm, the Reyes image rendering system is "An architecture ... for fast high-quality rendering of complex images."  Reyes was proposed as a collection of algorithms and data processing systems.  However, the terms "algorithm" and "architecture" have come to be used synonymously and are used interchangeably in this article.

PhotoWorks (ray tracing software): PhotoWorks is a raytrace rendering program created by Dassault Systèmes SolidWorks Corporation, formerly supplied as a photorealistic rendering add-in for SolidWorks.  The program is based on the Mental Ray rendering engine.  It has a library of scenes and materials that can be used with user-created SolidWorks files to create still frame images within the SolidWorks GUI.

David Salesin: David Salesin is an American computer scientist.  He has worked in computer graphics, three-dimensional and four-dimensional mathematics, and photorealistic rendering.  He is currently the Director of Snap Inc.  Research Team, an affiliate professor in the Department of Computer Science & Engineering of the University of Washington in Seattle, and previously director of the Adobe Creative Technologies Lab.

Peter Shirley: Peter Shirley (born 1963) is American computer scientist and computer graphics researcher.  He is a Distinguished Scientist at NVIDIA and adjunct professor at the University of Utah in computer science.  He has made extensive contributions to interactive photorealistic rendering.  His textbook, "Fundamentals of Computer Graphics", is considered one of the leading introductory texts on computer graphics and is currently in the fourth edition.

Supporting paragraphs: Blue Moon Rendering Tools The Cell
Answer: Blue Moon Rendering Tools