The PS4 Pro is definitely not powerful enough to support native 4K rendering for most games- instead, Sony uses a custom upscaling solution which is referred to as Checkerboarding. Checkerboarding can be a demanding technique, but if utilized right, with access to the triangle and object data in the ID buffer, the results can be visually resplendent.
“First, we can do the same ID-based colour propagation that we did for geometry rendering, so we can get some excellent spatial anti-aliasing before we even get into temporal, even without paying attention to the previous frame, we can create images of a higher quality than if our 4m color samples were arranged in a rectangular grid… In other words, image quality is immediately better than 1530p,” Mark Cerny explained to Eurogamer’s Digital Foundry.
“Second, we can use the colours and the IDs from the previous frame, which is to say that we can do some pretty darn good temporal anti-aliasing. Clearly if the camera isn’t moving we can insert the previous frame’s colours and essentially get perfect 4K imagery. But even if the camera is moving or parts of the scene are moving, we can use the IDs – both object ID and triangle ID to hunt for an appropriate part of the previous frame and use that. So the IDs give us some certainty about how to use the previous frame. ”
So far, so good. But what are the benefits of checkerboarding versus traditional geometry based rendering?
“[With] checkerboard rendering, the first two pluses are the same: crisp edges, detailed foliage, storm fences, but also, increased detail in textures, increased detail in specular effects,” Cerny said “But we’re doubling pixel shader workload, there are other overheads as well and it may not be possible to from 1080p native all the way up to 2160p checkerboard.”
The end result, however, is great looking games with relatively fewer resources and effort required.
“The point though is that these are techniques that can be implemented for a fraction of a per cent for the overall budget for the title,” Cerny said.
The PS4 Pro is due out next month, on November 10. It will be the first 4K capable console on the market (the Xbox One S technically supports 4K video, but for games, only goes as high as 1080p).
