*Sub-Thread* Dithering in GTA4

[aaronspink]

I must be missing those missing shadows. What's not shadowed that should be in those bowling shots? All I see is the ceiling shadows or whatever shifted (and the usual warmer red/yellow tint).

obvious missing shadows are in the laundry mat shots. The vent tubing isn't casting shadows in the PS3 version and the lighting in the missing ceiling tiles is also flat in PS3 version but properly lit and shadowed in the 360 version.

For the bowling shots, there are significant location and intensity differences for the lighting, but no shadow issues as far as I can tell.

 

[speedsix]

If you flick between the two night intro shots with the car posted above, the ladder and the striped yellow bars to the left of the ladder look to be lit differently to me.

 

[btdvox]

Its probably just the time of day your seeing. Also The ps3 is missing some shadows but barely any, It could be vice versa also i just havent noticed anything out of the ordinary on the 360.

The blurring is because its 640p and not 720p in one sense, its also the habit of the way ps3 renders to be a bit more warm and in some senses "blurrier" but this effect looks great in alot of games such as uncharted, heavenly sword etc.

 

[Shifty Geezer]

You don't render 'warmer' and 'blurrier'! If the PS3's rendering is blurry, it's defective! Graphics hardware renders one pixel, one colour. You need to process that data to introduce blur between pixels.

I have my fingers crossed that Eurogamer will explain all in their head-to-head where they promise something 'special'.

Oh, and those of you wondering where our GTA IV Xbox 360 vs. PS3 Face-Off is, hang on for another few days, because we have something special in store to help get to the bottom of what unites and divides the two versions.

An interview perhaps? I hope so!

 

[btdvox]

^^ I didnt mean to say it renders it that way- Im saying its the over all look of the PS3. If you see any comparison videos versus 360 and ps3 which im sure you have- You'' tell that the Ps3 is almost always much more warm toned than the 360. This has been from any game since launch that ive checked - that is multi platform that is.

 

[Magalini]

Best example of texture dithering in bowling alley

I'm loving this thread - really intriguing.

I have the 360 version, and have just finished my first bit of bowling. Of course I was looking out for the differences and texture problems. Best example I could see, and one that nobody else here has pointed out -

When you're up for your second bowl, getting in position - hit Y to see the scoreboard. Your previous bowling speed should be displayed in mph. Hit Y again to go back to the ready stance, and glance up at the scoreboard from there. The numbers on the board representing the speed are really messed up. They're almost complete garbage in fact.

Sorry - I don't have screenshots, but if anyone else wants to look that'd be a good place to do it.

 

[grandmaster]

I have my fingers crossed that Eurogamer will explain all in their head-to-head where they promise something 'special'.

An interview perhaps? I hope so!

It's rare that a studio will talk about what can be perceived as technical deficiencies, and rarer still that a high profile developer will express that they had difficulties with any given platform. Put it this way - I can't see any developer coming up with a politically correct way to say that they had to render their game at a sub-720p resolution on PS3. Were it not for the ugliness of the texture dithering on the 360 game, it would be easily apparent which version looks better.

So no interview in the Eurogamer coverage, but the face-off features are undergoing a radical overhaul at the moment. So the precision shots and stuff like that will remain but there'll be major improvements in the way we handle the material, and the approaches we're looking at are not being done anywhere else online.

 

[Jawed]

Using "sharpen more" in Photoshop to emphasise edges, one can clearly see that XB360 has "dithering" over the entire frame. It is not as selective as people appear to think it is.

XB360:

PS3:

Jawed

 

[Dopefish]

http://imk.cx/screenshots/xbox360/Grand Theft Auto IV/signdist/

Just some screenshots of me walking closer to a sign.

 

[Jawed]

Here the billboard gantry mostly consists of geometry. But one of the pieces, a flat horizontal plane, appears to be a single texture with alpha-transparency (hence what appears to be two separate "L"s). On XB360 this texture disintegrates into "dither".

XB360:

PS3

Jawed

 

[paawl]

I know I'm coming late to this party, and I have little 3D graphics expertise, so take this as merely a kernel of an idea for others to expand upon, but, is it possible that the 360 version is compressing the textures more to save disc space or disc read time? This was suggested as early as post #13.

I ask again because MS advocates, on slide 30 of this Gamefest 2007 presentation, using a software compression codec, called MCT, on top of the usual DXT. I tried finding out more about the method of MCT, but I found little. It appears from the slides to be a vector quantization scheme, so it could account for the appearance of dither within a texture. Importantly, on slide 31, MS notes that the quality of MCT is "variable", as opposed to "good" for DXT and "best" for the JPEG-like PCT.

If Rockstar is using this, or some other form of software compression, perhaps in addition to the on-the-fly generation of mipmaps, as suggested by Mintmaster, could it account for the dithering on the 360 version?

I know it has been pointed out (by Shifty, IIRC) that the same odd effect seems to occur where the neon lights intersect the electrical conduits. What I can't tell from the screenshots is whether the neon is distinct geometry, or a transparent texture applied to the wall, or is simply a part of the wall texture itself. Only in the latter two cases could texture compression explain the observed effect.

 

[Shifty Geezer]

I know it has been pointed out (by Shifty, IIRC) that the same odd effect seems to occur where the neon lights intersect the electrical conduits. What I can't tell from the screenshots is whether the neon is distinct geometry.

It's geometry as determined by the perfect pixel edges. A texture would see smoother sampling of the edges. Unless they've turned off mipmapping and are point-sampling the texture, which would be crazy! As for the compression idea, no schema would advocate the wholesale corruption of image data as is happening in this noise (remember it's noise, not dithering, in the spotty textures!). You may as well not generate mipmaps and use one big texture, which would almost halve your memory requirements from a texture POV and create just a messy a look (think PS2). Also XB360 has more available RAM for textures than PS3, so why use a more aggressive compression? They should be using the same assets.

 

[Philip42]

"The shadows are definately the biggest source of dithering. Rockstar really didn't try very hard on the 360 version. They got 720p with 2xAA and completely ignored this obvious texturing bug, ignored 360 specific features life fetch4, possibly used alpha blending on PS3 for trees/fences but alpha-to-coverage on the 360 version, and tweaked the light color on the PS3 version to a "warmer" tone that people like but forgot to do the same on 360"

Mintmaster,

Do you think this is a texturing bug for sure?

And why so?

TIA


btw: About the PS3's warmer tone(yellow tint compared to a blueish tint on the 360 version), my main fault with it, that it's far too bright in the daylight.

I'm having the same fault on the X360 version in terms of overdone brightness, but i can slide the sliders in a way where there is more of a sweet spot, then on the PS3 version.

P.S. I know it's not my HDTV, as it's a CRT-->34" Sony XBR960 that has been calibrated.

 

[Philip42]

It's geometry as determined by the perfect pixel edges. A texture would see smoother sampling of the edges. Unless they've turned off mipmapping and are point-sampling the texture, which would be crazy! As for the compression idea, no schema would advocate the wholesale corruption of image data as is happening in this noise (remember it's noise, not dithering, in the spotty textures!). You may as well not generate mipmaps and use one big texture, which would almost halve your memory requirements from a texture POV and create just a messy a look (think PS2). Also XB360 has more available RAM for textures than PS3, so why use a more aggressive compression? They should be using the same assets.

Except that the PS3 has the 3Gig HDD install as well.

I'm wondering if this could be a case where the HDD install plays something into how the LOD textures(if that is the method the PS3 uses) are being swapped into Ram. Maybe it's a case where the DVD-9 is just not fast enough to swap in textures in this size of a 'map'/'world' at the speed of the PS3's HDD?.

Is it possible the HDD install is playing a part into the difference(graphically, we know it does performance wise) texture quality wise, of the two versions?

Maybe the dithering/noise/aliasing(whichever it may be) problems many have noticed is because the 360 version is trying to get by using lesser LOD textures?

I'm probably way off base here, but i just thought i'd ask it.

 

[Mintmaster]

Using "sharpen more" in Photoshop to emphasise edges, one can clearly see that XB360 has "dithering" over the entire frame. It is not as selective as people appear to think it is.

Try it on an object with texture magnification. I don't think you see the same thing.

Having said that, a bug that affects all minified textures is not exactly selective.

 

[Jawed]

Try it on an object with texture magnification. I don't think you see the same thing.

Taken from:

http://dot50cal.the-horror.com/b3d/gta4/dithering/x3-image23.png

which is the only magnified texture I can think of as having been posted. The "spots" disappear at the extreme left edge of the frame where the magnification is greatest. I can only find two in the burger itself.

Jawed

 

[paawl]

It's geometry as determined by the perfect pixel edges. A texture would see smoother sampling of the edges. Unless they've turned off mipmapping and are point-sampling the texture, which would be crazy!

Good observation! That would appear to rule out it being due to texture corruption, and indicates some sort of post-processing effect gone awry.

As for the compression idea, no schema would advocate the wholesale corruption of image data as is happening in this noise (remember it's noise, not dithering, in the spotty textures!).

Well, I'm sure the intent of the compression scheme isn't to corrupt the textures, but, it is a lossy scheme, and MS notes that the quality is "variable".

You may as well not generate mipmaps and use one big texture, which would almost halve your memory requirements from a texture POV and create just a messy a look (think PS2).

I'm not sure how you get from the a lossy compression scheme not always having acceptable results to "you may as well not generate mipmaps and use one big texture".

Also XB360 has more available RAM for textures than PS3, so why use a more aggressive compression? They should be using the same assets.

Well, I was thinking about Sam Houser's comments about the Xbox 360 disc storage limitations, and the 360s lack of a standard HDD. The textures are decompressed (and mipmaps can be generated) as the data are streamed off of the disc; I don't think that they're stored compressed in memory. The advantage of compressing them is to save on disc space and to reduce loading times.

 

[Rockster]

Does anyone here have connections at Rockstar or the XNA Developer Connection group? Perhaps it would be worth sending out a couple emails to see if they want to participate in this thread. Could be interesting.

 

[grandmaster]

Thanks for the screenshots, grandmaster.

That laundromat shot has the same washer control face texture repeated, and you can gradually see it getting messed up in a way that I think fits my theory. Can you give me one screenshot where you get at close to the machine as possible, preferably with you facing it head on? If it's magnified enough, I can recreate part of that texture, screw up the first mipmap, and see if it gives the same symptoms in a 3D app.

I did a face-on washing machine shot for you but am not sure I'm close enough for you.

 

[Dot50Cal]

Off topic, but Hahahha at the FUD detergent. I didn't notice that

No other multiplatform game has shown any difference in tone like this, and techincally speaking there really shouldn't be one.

Part of the issue with tone comparisons is that the time of day is always changing. However, there are some PS3 screenshots where the light is more yellowish than any 360 shot, and you even see a shift this way indoors. My guess is that it was an artistic tweak implemented by the guys that coded the PS3 renderer.

I missed this post, but you are right. I have captures from PS3 / 360 to show the color difference here that proves this is something more than the native color output differences:
http://forum.beyond3d.com/showthread.php?t=46549