Imagination brings ray tracing to mobile GPUs

March 18, 2014
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PowerVR Ray Tracing - hybrid rendering

Imagination has announced a new family of GPUs that offer high-performance ray tracing capabilities in a chip that is suitable for use in smartphones and tablets. According to Imagination the new PowerVR Wizard GPU family unleashes the potential for highly photorealistic games and apps on the mobile platform, something that wasn’t previously possible.

Traditional GPUs use a series of techniques including rasterisation and deferred shading to create the best approximation of a scene. It does this by turning the objects in the scene into little triangles and then applies various shading techniques to make the scene look realistic. The faster the GPU, the smaller the triangles. The smaller the triangles, the smoother and more life-like the objects look.

There is an alternative technique, which you have probably heard of, called ray tracing. Rather than applying shading to the little triangles, ray tracing actually maps out the path of light as it travels in the scene and arrives at the viewers eye. As a result images can be produced which have better lighting, more realistic shadows and reflections and can even show how light refracts through objects. Ray tracing has been around for years but it has often been seen as the tool of those creating special effects and computer animated movies.

You would need a power budget upwards of 300W to achieve anything remotely close to the performance that PowerVR Ray Tracing-based hardware achieves.

What Imagination has done is build a GPU that can do both traditional rasterisation/shading and ray tracing to produce scenes that are rendered using a combination of both. The first chip in new PowerVR Wizard family is the PowerVR GR6500. It is based on the latest generation PowerVR Rogue design and includes 128 ALU cores which are capable of more than 150 GFLOPS (FP32) or 300 GFLOPS (FP16) at 600 MHz. But it also includes a specialized Ray Tracing Unit (RTU) which integrates fully with the rest of the GPU architecture. The RTU can process up to 300 million rays per second (MRPS), 24 billion node tests per second and 100 million dynamic triangles per second at 600 MHz. The result is an engine which can produce real-time, interactive ray traced graphics on mobile devices. The PowerVR GR6500 supports a range of 3D APIs including OpenGL ES 3.1/2.0/1.1, OpenGL 3.x, Direct3D 11 Level 10_0, OpenCL 1.2, and OpenRL 1.x.

PowerVR GR6500 GPU - PowerVR Wizard GPUs

By combining traditional graphics and ray tracing-based rendering, the new PowerVR GR6500 supports all existing game engines and tools while giving developers the possibility of adding a new level of quality and enhanced realism to apps and games via the real-time ray tracing. This “Hybrid rendering” means that the rasterised game engine produces most of the elements of the frame, and the ray tracer adds certain elements or effects, giving the best of both worlds.

The GPUs in the current-generation of desktop computers can also be programmed to do ray tracing, but according to Imagination you need desktop power consumption levels to do it, “you would need a power budget upwards of 300W to achieve anything remotely close to the performance that PowerVR Ray Tracing-based hardware achieves.” The beauty of the PowerVR GR6500 is that it gives game designers a budget of 300 million rays per second while using less power, making it suitable for mobile platforms.

owerVR Ray Tracing - rasterized rendering

PowerVR Ray Tracing - hybrid rendering

All this nice new tech would be a little pointless without support from game designers. The good news is that Imagination are teaming up with Unity Technologies to add the new PowerVR ray tracing technology into Unity’s game development engine. The first step in this partnership means that Unity will add Imagination’s real-time ray tracing technology into the upcoming release of Unity 5. “Artists and game designers will, through integration of Imagination’s ray tracing technology in Unity 5, immediately see their work with accurate lighting that matches the final look of their game,” said the two companies in a joint statement.

6_Unity 5 Lightmap Preview editor - PowerVR Ray Tracing

Over the longer term Unity and Imagination will work to add the new PowerVR Wizard Ray Tracing capabilities into the Unity engine. According to Unity, “integrating ray tracing directly into the game engine will lead to interactive game graphics that will look as realistic as CG movies do today.”

What do you think? Would you like to see an Android powered mobile device or even an Android powered gaming box use this new tech? Please let me know in the comments section below.

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