Ray tracing levels aims for clarity with imaging graphics SoCs - Embedded.com

Ray tracing levels aims for clarity with imaging graphics SoCs

All ray tracing capabilities on the market today are not equal. With more imaging graphics systems on chip (SoCs) using ray tracing acceleration, Imagination Technologies has developed a Ray Tracing Levels system to help developers and original equipment manufacturers (OEMs) to clearly understand the various different ray tracing implementations in currently being used and for the future.

The system is not necessarily aiming to be an industry benchmark, but an aid for developers to identify the vastly varying ray tracing capabilities and help compare like with like. The Ray Tracing Levels system identifies increasingly advanced stages of ray tracing acceleration, across a range of architectures, not just Imagination’s PowerVR ray tracing, with each level defining higher performance and better hardware utilization.

The grading system, from level 0 to level 5, translates to successively greater real-world ray tracing performance levels with better efficiency for more complex effects and higher resolutions.

Referring to the system, companies looking to deploy, or develop on, ray tracing solutions will be able to confidently understand the market and find the right technology to meet their needs. The Ray Tracing Levels system consists of six levels, with the capabilities and requirements described as follows:

  • Level 0: Legacy solutions
  • Level 1: Software on traditional GPUs
  • Level 2: Ray/box and ray/tri-testers in hardware
  • Level 3: Bounding Volume Hierarchy (BVH) processing in hardware
  • Level 4: BVH processing and coherency sorting in hardware
  • Level 5: Coherent BVH processing with Scene Hierarchy Generation (SHG) in hardware

A BVH Builder with SHG can also be added to lower efficiency levels where this would be indicated by the addition of “plus”, for example, “level 2 plus” solution.

Imagination Ray Tracing level 2
Bounding volume hierarchy in level 2 hardware speeds up ray/box ray/triangle testing. (Image: Imagination Technologies)

Jon Peddie, principle, Jon Peddie Research, said, “The Ray Tracing Levels system is exactly what is needed to understand and reap the benefits of ray tracing across a range of products. Ray tracing has long been considered the utopia of 3D graphics, but the proliferation of solutions makes it far from clear whether people are even referring to the same thing when they say, ‘ray tracing’. With this system, game engines, smartphone manufacturers and more have the insight to understand the differences between ray tracing implementations, speak with specificity about ray tracing, and, ultimately, enable consumers to enjoy incredibly realistic images on mobile devices, just like they do at the cinema.”

Kristof Beets, senior director of technical product management at Imagination Technologies, added, “Real-time ray tracing is the most exciting development in 3D graphics of the last 10 years. It’s a technology that everyone wants but not everyone understands, especially when it comes to the benefits on mobile. We want to change that. By creating the Ray Tracing Levels system, we’re helping to bring clarity to the industry about the confusing range of different ray tracing offerings.”

The key point that as one moves up each level, there is an increased focus on efficiency. As Imagination noted in a blog:

“The market however does not always move based on efficiency. For example, the recently released second-generation ray tracing-capable desktop PC hardware has increased performance by simply providing more ray tracing processing – which naturally requires more silicon area and more power. However, this brute force approach is not a viable option for solutions that need to operate within a power budget, such as mobile. Ray tracing is a rendering technique that accurately traces the path of light in a scene and can render believable reflection, refraction, and lighting effects with much higher degrees of realism and fidelity than traditional rasterization techniques.”

The company said gaining an understanding of ray tracing architecture is essential to put marketing performance metrics for ray tracing into context. For example, claims for GigaRays per second may initially impress but could pale in reality if there is low efficiency linked to low utilization of GPU processing resources, or due to memory access limitations as a result of the non-coherent memory access patterns.

Imagination’s Beets told embedded.com, “The market will have to adopt some aspects of this Ray Tracing Levels system, either through this naming or some other variation.” The company hopes that once ray tracing levels are understood, then SoC designers can enable their ray tracing implementations can move from low efficiency, high-power consumption hardware into area and power-efficient devices. This in turn would benefit mobile gamers looking for lifelike, photorealistic games and high levels of immersion.


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