Eric Demers and GCN, Part II

Company: AMD
Author: James Prior
Date: December 22nd, 2011

Anisotropic Filtering

R3D: We were pleased to see you've put together a team for investigating anisotropic filtering (AF), and are learning from that with some great new improvements there which I'm really looking forward to picking apart.

Eric: [laughing] I'm so happy to hear that ...

Eric: [laughing] More of a challenge!

Eric: Y'know, we didn't even put in [the presentation] all the changes we put in, we put in a lot of stuff but - I'll be honest with you, we never even saw the problems on Cayman until people started looking at it. Then we went back and we have about three or four guys that worked on this pretty consistently, a whole bunch of guys and the whole texture team. We found some problems and we fixed those and we found other things that we're going to fix over time as well. The one promise we can say is 'better'. For sure, better. I don't know if you guys could see it from there?

R3D: Yes, I could.

Eric: That is the only texture in the whole demo [ grass texture 2] that shows that, if you go to checkerboard they all look perfect. And the checkerboard is pretty high frequency.

Anisotropic Filtering Improvements

R3D: The checkerboard, when I was looking at, I had to get right up on the screen and at that point I wondered if it was actually the GPU or if it is the display processing chip inside the monitor?

Tom: [laughing] Yes.

Eric: I like the split screen because if you're getting getting interpolation on both sides you know its something else, right? It really was this high frequency ground texture that was showing it and even then it's very subtle. It was hard to come up with a test case to show it. There were some of our guys that would look at and just see it, 'oh yeah! There it is!' and sure, if that's your job then you may spot it faster. For me, and it was funny because Matt (Skynner) came in this morning and he looked at all of them and he said 'I can't see any of them'. I pointed at it with the laser and he said 'man, that's way subtle, they won't see that beyond the front row'.

R3D: If you know what you're looking for you'll find it pretty easily.

Eric: Yah, and magnification on BC4, BC5, there's a couple of other things that we improved that and you should be able to see those. I think Cayman was rocking and we still have the best rotation and variance and now this one [Tahiti] just makes it a little bit better.