Filtering and Perspective Correction

B

BigGreenMat

Member
I am just wondering. How much would it have cost for Nintendo to add these 2 rendering features into the DS hardware? I mean just these two things would have made the 3d on the machine SO much more palatable. What stopped them from adding it?
 
I'm curious myself, though Sony also 1-upped, to use a pun, Nintendo in controls as well. The disc analog control sounds really interesting and I do hope it works nicely.

But yes, back to the filtering, I don't get what's the problem with that. The shimmering effect is about the only thing that bothers me with the games. Not noticeable though after playing for a while. I'll get used to it, but I'm sure it'll never stop bothering me.
 
I'm curious to know how developers will work around this problem.

ss01a.jpg

ss01a.jpg

ss04a.jpg


IMO, These are the best looking shots I've seen for the DS.

I wonder why?
there's hardly any objects on screen
 
I'm pretty sure the DS has perspective correction, but I'd have to see the games myself to know for sure. Do you mean texture perspective correction, or geometry?
 
It can save you quite a bit of hardware while at the same time allowing you for quite a lot of polygons per second.

Forget about calculating STQ coordinates (Q = 1 / w; S = Q * s; T = Q * t... necessary for proper perspective corrected texturing), forget even (you certainly can) about 4x4 * 4x1 Matrix * Vector Multiplication or 4x4 * 4x4 Matrix * Matrix Multiplication... enter the world of 3x3 Matrices and 3x1 Vectors. Less calculations, whether you are doing them in software or in hardware.

Texture filtering is very expensive to do in software so let the 67 MHz ARM9 CPU to handle it is not an option and it does add a fair bit of circuitry to the GPU: you need higher VRAM bandwidth (you have to fetch 4 texels per pixel from the VRAM or your Texture Cache [which means extra logic]) and you need to place in the Texture-filtering Unit(s).

At this point those two features are goners: it would cause a massive delay to add them in the Hardware as they would have to re-design parts of the unit.

Perspective Correction can be done in Software: Tomb Raider 1 on PC had a High Quality option for the graphics that enabled Software based Perspective correction and besides if polygons are very small you will not notice texture's warping.
 
Tenkei said:
I'm pretty sure the DS has perspective correction, but I'd have to see the games myself to know for sure. Do you mean texture perspective correction, or geometry?
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Texture perspective correction which clearly lacks in ome games.

If the Hardware had it built-in they would use it: hey, even I managed to convert our PlayStation 2 engine to use STQ texture co-ordinates and thus enable perspective corrected texturing.
 
Mashing said:
Isn't that something that could be slipped in to future DS models?
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It would cost Nintendo a fair bit of money and the jump in graphics would be noticeable, too noticeable for early DS adopters.
 
They should've added it in as an optional feature even after developers got their development kits. 1995 3D graphics are just eye-cutting nowadays. Texture filtering really makes all the difference.
 
Drinky Crow said:
Like there won't be a DS SP.
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Well, shit, I'd bet dollars to donuts that there will be. But that doesn't mean they're going to up the system's processing power. Just a change to the form factor.
 
Sho Nuff said:
Yeah, it's not like anyone else uses filtering and perspective correction these days.

...
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... errr, right. i think you've missed the point of my post.
 
BigGreenMat said:
I am just wondering. How much would it have cost for Nintendo to add these 2 rendering features into the DS hardware? I mean just these two things would have made the 3d on the machine SO much more palatable. What stopped them from adding it?
Click to expand...
If you omit perspective correction, and the chip also doesn't use ZBuffer - you are effectivelly left with 2d accelerator (That's what PS1 and Saturn both are, btw), which obviously uses much less silicon to implement - cheaper, less battery use.

Filtering similarly adds some extra iterators/calculation, but also it eats up to 4xmore bandwith then unfiltered rendering.

Panajev said:
If the Hardware had it built-in they would use it:
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Depends - what if it's there, but halves your fillrate? (it's basically just a matter of having extra iterators per pixel - it could be possible to design some whacky loopback in hardware that works it out at extra cost).
I'd need to see it in motion, but ground in some screens looks perspective corrected - but there's also obvious warping on some other stuff.
 
Fafalada said:
Depends - what if it's there, but halves your fillrate? (it's basically just a matter of having extra iterators per pixel - it could be possible to design some whacky loopback in hardware that works it out at extra cost).
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Why do something like that ? Bah. I would not think that the cost of single cycle Perspective Correction in Hardware is as high as the cost of Texture Filterign (caches + TMUs).

I'd need to see it in motion, but ground in some screens looks perspective corrected - but there's also obvious warping on some other stuff.
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Let's see, the ground might be more finely tessellated than those objects which showed harsher texture warping.

Tomb Raider 4: The Last Revelation showed very minimal texture-warping compared to a lot of other PlayStation 2 games and developers admitted that they were working against texture warping by tessellating objects as they came closer to the camera (it was camera distance dependent tessellation IIRC).
 
Panajev said:
Why do something like that ? Bah.
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Well don't ask me, I was just thinking out loud :P Suppose that effect of filtering is minimized on the small screen, while warping is still clearly visible, especially on those ground textures close to camera.
Afaik PS1 GPU did something akin to this - it reused iterators for texture pass, that's how you got half the fillrate for texturing.

Let's see, the ground might be more finely tessellated than those objects which showed harsher texture warping.
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I know, but even the PS1 games that did that didn't eliminate the problem on ground planes. Now take for example that planar scroll mode on GBA (don't remember the number) that has perspective built in - it's rock solid.
 
Mode ? You can do that in all modes that support rotation and scaling of at least 1 background (I cannot remember which one does not allow at least 1 BG to be scaled and rotated)... then you go play with H-blanks by scaling each of the upcoming scan-lines accordingly... you basically change the scaling setting of the BG at almost every H-blank.

I know, but even the PS1 games that did that didn't eliminate the problem on ground planes.
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Not completely, but in most cases it did a pretty good job. Notice that on ground planes you always seem some traces of warping in all DS games.

Still you can do it in software as Tomb Raider 1 did on PC in one of the Graphics setttings.
 
I like this form-factor: I do not like the GBA SP vertical set-up, I like horizontal set-ups like the Game Gear, the GBA, the DS and the PSP.
 
Well I never coded for GBA, I just remember that thing required some mode in older machines :P
Anyway, does anyone know if DS has Z-Buffer? If not, that would pretty much confirm no persp.correction too.

Still you can do it in software as Tomb Raider 1 did on PC in one of the Graphics setttings.
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Well TR1 is a software renderer - of course they can choose how polygons are rasterized.
 
Wasn't there some point made somewhere about mainstream consumers not noticing the difference between texture filtered/perspective corrected 3d and non-such? I agree with that ideology. If no one's going to notice (except the hardcore gamers and early adopters), why invest the extra money (which has obvious drawbacks, such as battery life and system cost)?

Ok, so it'll look a little better. But that doesn't add anything to the game. Most DS games probably won't need it: Metroid Prime Hunters looks just fine. It's not like any of these games have glaring texture warps like MGS or VS had on PS1. And if they do, mainstream consumers will assume it's natural to the way the system works and not consider it a technical problem; i.e. they'll think it might look weird, but it's just something you deal wit much like you deal with ingame character models not looking 100% realistic.

As hardcore gamers ('hobbyists'), I think it's part of our responsibility to zoom out a bit and look at things from a realistic point of view, like the hardware manufacturer (in this case Nintendo) probably has done.

What's to benefit, really, from filtering/correction? I say: so little, it's negligeable. Costs outweigh benefits.
 
People notice, IMO...even the casuals. They are the same that buy the PS2 and home consoles...they're now accustomed to a certain level of visual refinement. Hardware-based filtering makes a big difference if your textures are going to be so blatantly low-res and full of color-banding. It's not super important, but it goes a long way toward making the games look more pleasing to the eye with long-term play. I still cannot understand why a 3D-capable system released in '04 doesn't have HW support for a HW feature that has pretty much been standard since '96-'97. It's far from high-tech.
 
filtered and to some extent perspective corrected textures is what made people go holy shit when they saw N64 for the first time.
 
Fafalada said:
Well I never coded for GBA, I just remember that thing required some mode in older machines :P
Anyway, does anyone know if DS has Z-Buffer? If not, that would pretty much confirm no persp.correction too.


Well TR1 is a software renderer - of course they can choose how polygons are rasterized.
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They say it has a hardware Z-buffer, but we have no confirmation yet.

I am sure milhouse and I could do some looking... how about PSP info to help us :P.

Not easily corruptible ? Ok, ok, we had to try.
 
My family members (hardly mainstream since they watched me grow up playing games) couldn't understand what specular surfaces were when I showed them Halo.

I think it's an illusion in that as long as the basics for real world interaction are there (3d, depth perception, movement, etc), then you can accept that as a recreation of reality on a tv screen. Anything beyond that won't be noticed if it's not there (such as refraction, real lighting, speculars, etc). Sure, we notice, but we're a trained eye, so to speak.

I agree that people may be used to seeing corrected textures etc. on home consoles. But comparing the handheld market to the home console market seems out of the way; compare it to the GBA (the main competitor for any new introductions to the handheld market) and 3d at this level is a huge improvement. I just don't see the argument when it's something as detailed as correction/filtering.

The change from 2d (GBA) to 3d (DS) is far bigger than raw (PS1) to filtered/corrected (N64). I think the former matters more to consumers than the latter.
 
I agree that people may be used to seeing corrected textures etc. on home consoles. But comparing the handheld market to the home console market seems out of the way; compare it to the GBA (the main competitor for any new introductions to the handheld market) and 3d at this level is a huge improvement. I just don't see the argument when it's something as detailed as correction/filtering.
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I don't really want to cause any arguments with this, but if Sony pushes the PSP hard enough...I think people will notice that DS is lacking from a visual standpoint. Will it matter in terms of sales? Perhaps not, but people will notice...

When a franchise makes an appearance on both platforms, I think it will become rather obvious.

Still, I think DS looks very nice. It's certainly more impressive than I expected...
 
Filtering is more of a practical feature rather than a fancy way of enabling visual detail. It's not eye-candy but, rather, a practical enhancement. To me, it's like playing Doom (1 or 2) or Quake 1 without filtering at a low resolution (something close to the 256 x 192 that the DS does)...it just looks fucking awful and can make the visuals unclear and muddied...negatively affecting the play experience. Sure, a game can be designed to try and avoid hectic or busy situations by using relatively simple level designs and high-contrast color schemes, but that seems very counter-creativity to me. Why impose these sorts of limitations when they didn't have to be there? I'm sure there will be ways around this, but at what cost?
 
There was plenty of creativity on PS1, so I don't think that's really a relevant argument. Certainly when the primary features of the DS rely not so much on 3d graphics as the type of game design in the first place. For example, consider the sudden availability of touch, dual screens, microphone, and wireless play. These factors increase the implementation rate of game concepts, be they 3d or 2d. So I think that something as infinitely detailed as correction/filtering comes out as minute compared to the new possibilities these new hardware features endow. That's how Nintendo's vision comes across to me anyway.
 
Rahul said:
There was plenty of creativity on PS1, so I don't think that's really a relevant argument.
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Sorry...I meant in a visual sense. And I didn't mean it would limit creativity...just that it seems like an unecessary limitation to impose on the developers.


Certainly when the primary features of the DS rely not so much on 3d graphics as the type of game design in the first place. For example, consider the sudden availability of touch, dual screens, microphone, and wireless play. These factors increase the implementation rate of game concepts, be they 3d or 2d. So I think that something as infinitely detailed as correction/filtering comes out as minute compared to the new possibilities these new hardware features endow. That's how Nintendo's vision comes across to me anyway.
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Yeah, I understand the balancing act...but this is a very low-end and standard feature that has been around for years. As this is a topic based on visual features, I was only responding based on that.
 
ninge said:
it does have hardware z and perspective correction :)
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Then why don't they use it DAMNIT ???!!!!!!!???

To have a too slow perspective corrections sound sto me like Sony engineers saying: hey, hey we do have mip-mapping... and I know some people would become very violent hearing these words.
 
Shompola said:
filtered and to some extent perspective corrected textures is what made people go holy shit when they saw N64 for the first time.
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Seriously, that and the minimal anti-aliasing the N64 had was what set it apart from the PSX. Take those three away and you're left with a console that produces sub-psx graphics. It really does make a difference to me.

On a similiar note, some PS2 games have unfiltered textures(like RRV...at least the textures on the cars/engines). WTF is the deal with that? :P
 
You know what's funny about casuals? In the PS1 time, Nfans would never cease to bitch the Ps1 for it's lack of perspective correcting and texture filtering.
But now with thh DS, they'll be like "ah man common, it's not important"
Just watch.
 
It's not as noticable in motion as it is in still screens, especially since unlike some PS1 games, DS games do not seem to have that jittery look to them (I apologize for my lack of technical terminology :) ).

The pixelated textures are there, of course, but in motion they don't look as bad, and overall the games are much more stable than some PS1 software.
 
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