Digital Foundry Article Technical Discussion Archive [2009]

[Laa-Yosh]

Joker, if you're still here, I was wondering about the various tradeoffs between resolution and AA when you're unable to use tiling on the X360. I think 60fps and a complex scenery with many vertical elements and with lots of particle effects pretty much rules tiling out.

So, for some reason IW prefers a sub-HD resolution with 2xAA instead of going full 720p noAA... I'd expect performance reasons, 600p 2xAA has less fragments to render and less texture reads maybe?

 

[assurdum]

I saw you post something similar over at EG. What makes you so sure the game is sub-HD due to the 360 and eDRAM? As the PS3 tends to struggle far more than the 360 with framerate, it seems just as likely to me that the sub-HD decision is so that the PS3 can maintain a fairly decent framerate and that the 360 version is the same resolution to maintain console parity.

ng 2 is sub hd on 360 for the same reason. TR underworld. I really doubt 600p is only caused of the ps3, not have much sense ... there are a lot of game hd & sub in the multi (more on ps3). Even on 360 fps dips below 60 so I think is obvious that is a choice forced.

 

[AlNom]

So, for some reason IW prefers a sub-HD resolution with 2xAA instead of going full 720p noAA... I'd expect performance reasons, 600p 2xAA has less fragments to render and less texture reads maybe?

Right, pixel shaders are run per-pixel, not per sample. 720p would be a 33% increase in pixel shader load. Bandwidth requirements are actually a bit higher for 1024x600 2x though (33% more).

I really doubt 600p is only caused of the ps3, not have much sense ... there are a lot of game hd & sub in the multi (more on ps3). Even on 360 fps dips below 60 so I think is obvious that is a choice forced.

The eDRAM sets a workable goal since Xenos will have all its fillrate available (and sans redundant geometry processing) although it is still a finite resource on either system. Given all the explosions and smoke and overdraw, rendering 33% more pixels would not have helped them towards 60fps.

 

[Laa-Yosh]

Yeah but less fragments require less texture reads as well, and that's actually about more then bandwith, at least on the 360 as far as I know, with its limited TMU capacity.

Also, 600p 2xAA uses 100% of the EDRAM compared to a single 720p buffer, so we could say that the subHD res is actually a more efficient use of the hardware, right?

 

[assurdum]

Right, pixel shaders are run per-pixel, not per sample. 720p would be a 33% increase in pixel shader load. Bandwidth requirements are actually a bit higher for 1024x600 2x though (33% more).



The eDRAM sets a workable goal since Xenos will have all its fillrate available (and sans redundant geometry processing) although it is still a finite resource on either system. Given all the explosions and smoke and overdraw, rendering 33% more pixels would not have helped them towards 60fps.

Yeah I expected something of that. The 60 fps require sacrifice in this generations.

 

[AlNom]

Yeah but less fragments require less texture reads as well, and that's actually about more then bandwith, at least on the 360 as far as I know, with its limited TMU capacity.

Assuming they don't use negative lod bias. *cough* But yes, you're right. One would actually get better cache hits with a higher resolution target with proper mip-mapping ( higher pixel : texel ratio) so fewer texture lookups needed.

Also, 600p 2xAA uses 100% of the EDRAM compared to a single 720p buffer, so we could say that the subHD res is actually a more efficient use of the hardware, right?

Perhaps. It's even "more efficient" if they can leverage the MSAA on say reflections or linearly filterable shadow maps or particle/alpha rendering for instance.

 

[joker454]

Joker, if you're still here, I was wondering about the various tradeoffs between resolution and AA when you're unable to use tiling on the X360. I think 60fps and a complex scenery with many vertical elements and with lots of particle effects pretty much rules tiling out.

So, for some reason IW prefers a sub-HD resolution with 2xAA instead of going full 720p noAA... I'd expect performance reasons, 600p 2xAA has less fragments to render and less texture reads maybe?

Quick answer as Bill & Ted's Excellent Adventure is on I figure if tiling was the main issue then they would have gone with 1024x640 instead of 1024x600, since the former fits in edram with 2xmsaa. But they dropped an additional 40 vertical lines down to 600p, so they must be pixel shader limited. I don't know if it would be alu or texture limited though, just got the game today but haven't tried it yet. Usually though it tends to be alu limited.

Incidentally, particle effects are handled by tiling easily because they are usually simple quads. So even if you had to process all their verts twice, it would still be a tiny increase in overall vert load for the entire particle system.

Vertical elements are only a pain if they aren't broken up. The soldiers are probably broken up into parts (head, legs, arms, torso, weapon) so they aren't as bad as one would think. The buildings might be though depending on how they are designed.

 

[liolio]

Joker454 when you get your hand on MW2 could you give an eye at the particle resolution.
In the article they criticize Infinity Ward for not using lower resolution particle on the ps3 and think it might be one of the reason behind the performance differences.
I think it's a bit unfair to them, they already render sub HD resolution, it's possible/likely that particle on both systems are rendered at even lower resolution. They may have lowered it but it may have become visible then they would have been pummelled for that too, tough choice.
what's your take?

 

[Billy Idol]

Is it just my eyes, or is smoke better looking on Xbox 360. I liked that the smoke often lasts very long and that it is even used to pepper up gameplay...but on the PS3, the smoke sometimes looked 'cartoony' (sorry, cannot find a better expression)...at a first sight, comparable to the smoke in R&C:ACiT.
And comparing the smoke for instance to the smoke in KZ2, it is really different looking.

 

[AlNom]

In the article they criticize Infinity Ward for not using lower resolution particle on the ps3 and think it might be one of the reason behind the performance differences.
I think it's a bit unfair to them, they already render sub HD resolution, it's possible/likely that particle on both systems are rendered at even lower resolution. They may have lowered it but it may have become visible then they would have been pummelled for that too, tough choice.

They already use lower res buffers, but they're comparing it to WaW, which used even lower res on PS3.

 

[Kasersky]

does the pc version have different set of textures or is it because the low resolution of the console version that makes the game appear less detailed?

@Silent_Buddha
blu-ray 2x is 8MBps, while 12xdvd(1st layer) is 8.2-16.5MBps, and 8xdvd(2nd layer) is on average 10MBps

but speeds can be improved by careful disc data layout and i think the inner rim of 360 discs are reserved for security data so most of the data is along the outer rim which skews the average read speed much higher. So double the read speed sounds very plausible.

 

[AlNom]

does the pc version have different set of textures or is it because the low resolution of the console version that makes the game appear less detailed?

Higher resolution textures.

 

[liolio]

interesting, After nitpick/digging attempts I've to say that they did a pretty good job on that game, they went way deeper than most others D-F wannabee. Serious job.

 

[ihamoitc2005]

Wow!

http://www3.telus.net/public/dhwag/NGS2_polydecuction_01.jpg

The character model is much better. I cannot believe this.

Also, question for Digital Foundry. Will digital foundry do a technical comparison for Infamous with other sandbox games?

Every other sandbox games like Prototype have ugly graphics. It will be good to explore how is Infamous looking so amazing and having so much detail and HDR using the same GPU when other games do not.

Nice Digital Foundry videos with some information:

http://www.eurogamer.net/articles/infamous-demo-investigated-blog-entry

http://www.eurogamer.net/articles/infamous-how-high-can-you-try

 

[Neb]

Every other sandbox games like Prototype have ugly graphics. It will be good to explore how is Infamous looking so amazing and having so much detail and HDR using the same GPU when other games do not.

Nice Digital Foundry videos with some information:

http://www.eurogamer.net/articles/infamous-demo-investigated-blog-entry

http://www.eurogamer.net/articles/infamous-how-high-can-you-try

Well sandbox game like GTAIV sports HDR, multiple lightsources and particle physics with world/dynamic objects to name some few things.

This video by DF is from PS3 version of GTAIV.
http://www.eurogamer.net/articles/digitalfoundry-gtaiv-time-lapse-video-blog-entry

 

[assen]

Vertical elements are only a pain if they aren't broken up. The soldiers are probably broken up into parts (head, legs, arms, torso, weapon) so they aren't as bad as one would think. The buildings might be though depending on how they are designed.

You mentioned vertical elements as a problem in tiling - but surely you can use a vertical split of the screen when tiling, if most of your polygons come from vertical elements?

 

[ihamoitc2005]

Well sandbox game like GTAIV sports HDR, multiple lightsources and particle physics with world/dynamic objects to name some few things.

This video by DF is from PS3 version of GTAIV.
http://www.eurogamer.net/articles/digitalfoundry-gtaiv-time-lapse-video-blog-entry

Thank you for the link.

Infamous also has HDR, multiple lightsources and particle physics with world/dynamic objects, no? You can even go above the buildings and jump down to the street from the top.

But textures and shaders are much more pretty and detailed. Even characters are better. What I wonder is why there is this difference.

 

[ihamoitc2005]

But Joshua's point is that they have made a lot of PS3 optimizations - the port is much better and closer to the X360 version then before.

Is there a big difference from COD4? I don't know. Frame-rate is worse, no? So hard to know if actual performance is better or only maybe different performance/quality trade.

 

[Laa-Yosh]

You mentioned vertical elements as a problem in tiling - but surely you can use a vertical split of the screen when tiling, if most of your polygons come from vertical elements?

Heh, ILM did something like that for rendering the clone armies in SW Episode II. However, the rendering engine did not support that - so they turned the camera on its side instead

 

[semitope]

Thank you for the link.

Infamous also has HDR, multiple lightsources and particle physics with world/dynamic objects, no? You can even go above the buildings and jump down to the street from the top.

But textures and shaders are much more pretty and detailed. Even characters are better. What I wonder is why there is this difference.

Great and interesting articles could be written comparing tech in these games but I see nothing like that. I too am impressed with infamous as an open world game and look forward to an infamous 2 to see what they can do.

In infamous ppl complain of a bit of pop-in though so maybe its not perfect. I'd also be interested in seeing any presentations the devs might have made about the tech used and spu and rsx usage % etc