Several years ago, I met with the team in San Francisco, CA. They had the pitch about "changing the game" just like every other company that has tried to get an article out, but there was something that caught my eye. The team was working on making Ray-tracing possible and affordable. It was at the time while Intel was banging on ray-tracing drum with their unsuccessful "Larrabee" GPGPU architecture (which came to market 4 years later as Xeon Phi, an accelerator board), while Nvidia was silently shipping hundreds, if not thousands of Intel Xeon processors as a consequence of acquiring Mental Ray, the leader in Ray-tracing. And naturally, demoing Ray-tracing being done on Tesla and Quadro graphics boards.

The company was named Caustic, out of San Francisco, CA. When I saw their prototype, it was little more than a stock FPGA with custom software, with engineers having an idea about building silicon of their own. Now, any company that develops a chip in the 21st century deserves serious kudos, and Caustic hasn’t disappointed us.

Today, Caustic is a wholly-owned subsidiary of Imagination Technologies, one of world leaders in graphics technology (for example, powering all Apple mobile devices, a lot of Intel SoC/CPUs) with their PowerVR graphics processor. The Ray-tracing boards which are being announced today are Caustic Series2 R2100 and Caustic Series2 R2500. Without any doubt, these two are bound to do more than head turning, since their specifications even beat well-established players such as AMD, Intel or Nvidia. Bear in mind that we are not talking about GPUs here, since Caustic manufactures Accelerator Boards. In order to describe the Caustic chips, Imagination Technologies has come up with the term Ray-Tracing Unit or RTU.

Caustic Series2 R2500 16GB
We start the look into today’s announcement with the highest performing part, the R2500. This is a dual-RTU (Ray-Tracing Unit) board, equipped with two RT2 chips and no less than 16GB of DDR2 memory operating at 400 MHz (that’s "800 MHz"). While DDR2 memory on a 2013 part belongs to "and now, something completely different" category, bear in mind that Series2 is a product of years of development and the manufacturer obviously saw no need to deal with extra latencies introduced with DDR3 memory. GDDR5 memory was not the possibility, since it requires active driving (different approach to the memory controller design) and as we’ve all seen it – no manufacturer is able to ship more than single-digit amounts of memory (8GB on Xeon Phi 5100P, Tesla K10).

Very long, yet compact design: single-slot, heatsinks that resemble 3dfx Voodoo5 5500, and probably record amount of memory chips on the PCB: 32 DDR2 chips. Yet, it doesn't require extra power.
Very long, yet compact design: single-slot, heatsinks that resemble 3dfx Voodoo5 5500 and probably the record amount of memory chips on the PCB itself: 32 DDR2 chips. Yet, it doesn’t require any extra power.

The two RT2 chips and 32 4Gbit Micron DDR2 chips (512MB) know how to save power, too. This board only consumes 65 Watts at its peak. As a consequence of this power-optimized design, the cooling is a simple 1-slot solution, and there are no 6- or 8-pin power plugs present. The R2500 should fit in most of chassis on the market but bear in mind that for best results, Imagination Technologies recommend that you pair it with a dual CPU configuration (2P).

While Imagination Technologies will hope there’s still DDR2-800 memory available on the market at the end of product cycle, nobody can say that it does not come at a very attractive price: $1495. For that amount of money, you get enough computing power to calculate up to 100 million incoherent rays per second. Here are the specs from Imagination Technologies themselves:

  • Up to 100 million incoherent rays per second
  • Target workstation: Dual CPU
  • Bus: PCIe x16 Gen 2.0 – single height, full length
  • Power: 65 Watts maximum, bus powered (no PCIe external power required)
  • OS Support: Windows 7 and Vista (32-bit and 64-bit)
  • On-board memory: 16 GB of scene geometry (up to 120 million triangles)
  • System memory: same requirements as 3D application (e.g., Maya). For optimal performance all memory channels should be fully populated
  • Ray-tracing hardware: two Caustic RT2 (ray-tracing unit) chips

Caustic Series2 R2100 4GB
Since the dual-RTU board consumed only 65 Watts, we expected to see the continuation of the power saving design, and Imagination Technologies did not disappoint. 30 Watts fewer than 100% load is something we forgot, given the power hungry nature of desktop/workstation GPUs and other accelerator boards. R2100 is consisted out of a single RT2 chip and 4GB of DDR2-800 memory. The chip will calculate up to 50 million incoherent rays per second, and for ideal results, it needs to be paired with a single CPU.

This board comes to market for only $795 and you can see the official specs below:

  • Up to 50 million incoherent rays per second
  • Target workstation: Single CPU
  • Bus: PCIe x8 Gen 2.0 – single height, half length
  • Power: 30 Watts maximum, bus powered (no PCIe external power required)
  • OS Support: Windows 7 and Vista (32-bit and 64-bit)
  • On-board memory: 4 GB of scene geometry (up to 60 million triangles)
  • System memory: same requirements as 3D application (e.g., Maya). For optimal performance all memory channels should be fully populated
  • Ray-tracing hardware: one Caustic RT2 RTU (Ray-Tracing Unit) chip

Software Support
Naturally, hardware is nothing without software support, and this is where we see Caustic becoming quite a big player. The company could have released the silicon a while ago (as you can see by the memory used, this was in the works for quite some time now), but they did not want to come to the market without fully developed set of tools that would make this hardware usable from day one.

Sunglasses created in Autodesk Maya, rendered using Caustic Visualizer for Maya
Sunglasses created in Autodesk Maya, rendered using Caustic Visualizer for Maya

Thus, we are not surprised to see Imagination announcing the Caustic Visualizer for Maya. During the initial ramp up of the parts, the company will bundle the Visualizer for free, after which the software will retail for $299. Furthermore, Caustic Visualizer for 3ds Max will become available during the second quarter of this year, with public beta starting in March 2013.

Autodesk Maya 2013 - creation of sunglasses used to demo Caustic Ray-tracing hardware
Autodesk Maya 2013 – creation of sunglasses used to demo Caustic Ray-tracing hardware

If you want to know more about the model, Caustic / Imagination supplied the following details:

  • Title: Sunglasses_01 & Sunglasses_02
  • Artists: Ryan Montrucchio
  • Models: Courtesy of Pacific Digital Image Visual Studios
  • Description: Rendered directly in the viewport with Caustic Visualizer for Autodesk® Maya® 2013. Triangles 538,696; Lights 10 + IBL. Uses mental ray® materials, and Image Based Lighting.

The company claims up to 5x acceleration over software alone, which for example, would negate the need for a second CPU – rather a workstation equipped with a single CPU and the RT2 RTU. Naturally, the company avoided direct confrontation against AMD and Nvidia-based hardware, leaving it to the reviewers.

Visualizer is based around PowerVR Brazil SDK v1.0, which is "a high-level software toolkit built using OpenRL API for adding photorealistic visualization into 3D graphics applications." In short, this is yet another acquisition by Imagination Technologies, providing hardware for its BrazilTM final frame renderer.

Conclusion
There’s no doubt, the market for discrete ray-tracers is growing day by day. This computing method was considered as unsuitable for real time purpose, paving way for less compute intensive methods (read: rasterizing), but with the growth of GPUs and specialized hardware such as this RTU, real-time ray-tracing is mere years away. Or less, if you take a look at what computational maps and Lightstage did with OTOY and their Octane render.

We will remain cautious until Imagination delivers the boards for testing, but on paper this is one potent, and more importantly, affordable combination. With Nvidia, AMD, Intel and now Imagination battling for the market, we finally have a reason to be excited about Ray-Tracing in computer graphics – it will become even a big factor in our everyday lives. Are you ready?