Digital Foundry Article Technical Discussion Archive [2011]

[Shifty Geezer]

Well, normals are RGB 24 bits at least; If you do colored spec, that's 4 bytes; if you do monochrome, it's 2 bytes.

So at least 2x the read speed required. I can't see there being that much free capacity in the game at the moment, and we're not going to see HDDs get significantly faster. A 10k RPM HDD in a PC will do a lot better than 5k RPM HDD in the current consoles, but I'm not seeing the potential for VR to match the detail of standard texturing until the standard is fast SSDs.

 

[Gitaroo]

can we expect a quick run down on arkham city before the game hit? Kind of want to see which version is better before I buy.

 

[NRP]

I've been playing Rage a bit on the 360, and while it looks good at times, I can't help but think this megatexture thing (or at least id's version of it) has too many trade offs for the visuals it delivers. Overall, I'm not that impressed. I might have been more impressed had I not already played Reach, Gears, BF3, Crysis 2, Red Dead Redemption, Uncharted, etc. Rage is pretty mediocre overall imo.

I mean, listening to some of you guys talking about "ooh . . . imagine what they could do with 50GB or 100GB of storage!" kind of makes me laugh. All that space and long development time and they can't even match what other devs have done with a fraction of it. It makes me think there have been some fundamentally incorrect decisions made somewhere.

 

[djskribbles]

You also have to consider that it's an almost solid 60fps.

 

[NRP]

Not worth it imo. The gameplay doesn't need 60 FPS. It needs to look better, be more interactive, and be "bigger". It's ironic that despite all the vast landscapes you really can't go anywhere except follow a fairly linear path. It feels like a corridor shooter in an outdoor setting.

Anyway, my point isn't to rag on Rage. I really hope other devs can do something more compelling with this megatexture/virtual texturing technology.

 

[Laa-Yosh]

So at least 2x the read speed required. I can't see there being that much free capacity in the game at the moment, and we're not going to see HDDs get significantly faster. A 10k RPM HDD in a PC will do a lot better than 5k RPM HDD in the current consoles, but I'm not seeing the potential for VR to match the detail of standard texturing until the standard is fast SSDs.

Are you intentionally ignoring part of my post?
Most of the town areas have full normals and speculars on every surface and the loading doesn't seem to cause problems there.

I'd say there are some other factors involved, for example a simple canyon area with low amounts of overdraw is a far easier case for the streaming, compared to a lot of buildings or a complex interior space like a power plant with railings pipes and random objects etc.

All in all, cutting out these extra texture layers was more of a disk space driven decision. It probably would have caused some more streaming issues as well, but the number one reason had to be the need to fit the campaign on two DVDs for the X360.

 

[Laa-Yosh]

That's your opinion, NRP, just as valid as the opinion of people who agree with id's decisions and trade-offs.

 

[Fafalada]

What would normal be? 16 bits? 8 bits for specular?

I imagine they'd compress them the same way they compress RGB channels - so closer to 2-3bits/texel (besides the point though, it's still at least doubling the texture data to load).
Though on consoles which are apparently memory-limited on caching too, you'd get additional overhead from paging-in things more often to memory as well.

 

[Shifty Geezer]

Are you intentionally ignoring part of my post? :smile:
Most of the town areas have full normals and speculars on every surface and the loading doesn't seem to cause problems there.

I'm getting lost here. VT in Rage is just colour, right, and those objects with normal and specular maps are conventionally textured?

I imagine they'd compress them the same way they compress RGB channels - so closer to 2-3bits/texel (besides the point though, it's still at least doubling the texture data to load).

For some reason I was thinking normals would need higher resolution, but of course it's just an RGB image so can be compressed the same.

Looking forward to designing a new console with VT in mind, wouldn't a good glob of cheap RAM solve the streaming issues most economically? Say 4GBs of whatever the cheapest DDR is. I don't think flash RAM as a cache is going to cut it unless we can get SSD speed, which isn't going to happen affordably by next-gen. If we replaced that with volatile RAM instead, we'd have the performance. Especially if we move onto things like megameshes, streaming datasets will be a significant load on a system and it'd have to be designed for it IMO.

 

[Laa-Yosh]

I'm getting lost here. VT in Rage is just colour, right, and those objects with normal and specular maps are conventionally textured?

No, objects that have normal and specular data need to be uniquely textured too. Think about characters, weapons, where it's more obvious why tiling and re-use wouldn't work.

So at asset creation, everything is created with unique color, normal and spec/gloss information. The source texture actually has 12 bytes of data per texel according to the VT presentation from id.
This data is still used in the game in that it's necessary to calculate the baked diffuse lighting and the baked specular highlights. But it is only included on the shipping DVD for objects that have at least some level of dynamic lighting - cars, characters, moving objects, and some of the town location environments. The rest of these maps are only present on id's server that stores the source data.

For some reason I was thinking normals would need higher resolution, but of course it's just an RGB image so can be compressed the same.

Nope, in fact it's a common console optimization to downscale normal maps (and speculars) especially if the lighting is soft and the material isn't highly reflective or shiny. Mass Effect 2 does this as far as I know, Assassin's Creed 2 even re-uses the same head geometry and UVs for every character so that they have only one spec map for everyone, and so on.

Looking forward to designing a new console with VT in mind, wouldn't a good glob of cheap RAM solve the streaming issues most economically? Say 4GBs of whatever the cheapest DDR is.

No, because you can't guarantee to have the tiles of the upcoming area present in that 4 GB, you can not avoid running into the worst case from time to time. Granted, if memory is so low that turning 180 degrees will already drop some tiles then it's a cheaper solution. But overall, it's preferable to bring the worst case closer to the average case.

I don't think flash RAM as a cache is going to cut it unless we can get SSD speed, which isn't going to happen affordably by next-gen.

We'll see, I think a lot of devs would really like it. Noone has really tested what it could do yet, because no system has it included as a default, but I'm sure it'd make a lot of other new tech possible as well. Imagine what a GTA type game game could do with it!
Although I'm personally wondering about whether an SSD can last for a console's lifespan without noticeable degradation - it'd be bad if one would have to replace it...

 

[TheWretched]

Well, one thing you have to consider in Rages towns. Your sprint ability is SEVERLY cut down (i.e. you can't sprint very far, compared to outside environments). That is surely one of the concessions id had to go through to make the towns work better.

 

[FATBOT]

Crysis Face-Off

http://www.eurogamer.net/articles/digitalfoundry-crysis-face-off

Better visuals for 360, except shadow filtering. 360 has also much better performance.

 

[assurdum]

I'm a bit confused... in 3D mode crysis on ps3 works out at full 720p but not in 2d... what the...

 

[Rangers]

Seems I was wrong.

 

[dragonelite]

I'm a bit confused... in 3D mode crysis on ps3 works out at full 720p but not in 2d... what the...

It probably sends two 720p packed frames but upsized not native.

 

[Barbarian]

Well, normals are RGB 24 bits at least; specular needs an intensity/color and a power/gloss/roughness element too. If you do colored spec, that's 4 bytes; if you do monochrome, it's 2 bytes.

It's fairly standard practice to store 2-component normal maps (as long as they are in tangent space). On Xbox and PC the best option is DXN/BC5, while on PS3 you have to live with DXT5nm.
Alternatively you can store 1-channel hightmap and reconstruct the normal during streaming or in the shader.

As to specular, if you don't need to have exposed color metals like gold and copper, and other special case things like oil spills, you can get away with monochrome specular intensity.

I haven't played Rage yet, only seen videos, and while it does look "painterly" I do think that it's sort of subpar to ship a diffuse-only game in 2011.

 

[assurdum]

It's fairly standard practice to store 2-component normal maps (as long as they are in tangent space). On Xbox and PC the best option is DXN/BC5, while on PS3 you have to live with DXT5nm.
Alternatively you can store 1-channel hightmap and reconstruct the normal during streaming or in the shader.

As to specular, if you don't need to have exposed color metals like gold and copper, and other special case things like oil spills, you can get away with monochrome specular intensity.

I haven't played Rage yet, only seen videos, and while it does look "painterly" I do think that it's sort of subpar to ship a diffuse-only game in 2011.

Forgive me but what do you means exactly? I haven't understood, really, don't let me wrong.

 

[Shifty Geezer]

No fancy shaders can be used as everything is defined just by colour. That's very last-gen, static scenery, and you're locked into a 'painterly/cartoon' look because you can't pull off any other looks. For VT to gain traction, IMO, it needs to offer 'deeper' information, which means much more data streaming.

 

[Nesh]

Are you guys also planning to write an analysis on F4?

 

[Richard]

You guys should have paid more attention to JC's QCon keynote from 2-3 years. Of course, we'd suspected as much since ETQW's release but that's when he confirmed world geometry would only get diffuse (static lighting) while dynamic objects would get normal maps and translucent geometry would get even more channels. IIRC this last MT type was replaced with regular texturing, probably wouldn't have looked too good to have HUD pop-in , the extra channels would mean a very large file size and perhaps the transcoding of alpha channels would cause further delays.

Anyway, regarding Crysis face-off, DF needs HTML5 video. The removal of indoor misc detail throughout the levels is insidious, as is the removal of the most taxing level of all "because it wasn't fun" (did they remove every single vehicle from the game then? ). Also, just like the IQ comparison I would have liked to see a performance comparison between console and pc.