Checkerboarding up to full 4K is more demanding and requires half the basic resolution - a 1920x2160 buffer - but with access to the triangle and object data in the ID buffer, beautiful things can happen as technique upon technique layers over the base checkerboard output.
"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 colour samples were arranged in a rectangular grid... In other words, image quality is immediately better than 1530p," Cerny explains earnestly.
"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. "
