*renamed* Lighting and shadows in games

M

muungano

Newcomer
After eyeballing both games (GTA4 and MGS4). I´ve found that the shadow on MGS4 looks really bad. Shadowmaps are so lo res and blootchy they seem to crawl.

On the other hand dispite larger world, the shadows in GTA4 has a blur filter to them which makes them smooth.

The question is why is not MGS4 using the same technique. Is there some technical limition on MGS4 or is it an pure art thing?

And what do you prefer? Blurry and soft or hard and jaggy.
 
Hi! Just a heads up, we frown upon versus threads, but your questions do have some merit across games in general.

The differences are really just down to the techniques involved, and some developers may not yet have caught up on the cutting edge tech.
 
Yes, rephrasing the topic somewhat, we have in GTA and MGS two expansive city environments employing different shadowing techniques with different results. Shadowing is one of the big eyesores in the current generation. We've progressed onto having shadows which is great, rather than lots of prebaked textures, but a lot of titles are using low-res maps that are seriously pixelated and detract as much from the game as they add in some cases. Another example is Heavenly Sword's self-shadowing, which in theory was wonderful, but the shimmer was in conflict to the fantastic models and graphics overall.

So what technique is GTA employing to good effect (in some people's eyes. I haven't been paying enough attention!), and how are they able to use it where other titles don't?
 
Shifty Geezer said:
So what technique is GTA employing to good effect (in some people's eyes. I haven't been paying enough attention!), and how are they able to use it where other titles don't?
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I don't know if I'm allowed to say it outright... but there was a certain talk at GDC this year from a certain someone here. :p
 
Thanks for rename.

What are the problems with creating good shadows in consoles then. On a PC you had it for years, since hf2 (at least :0 ).

What makes out how large shadow maps one can use. And whar makes out the blur filtering. I mean from an art stand point I think that most nextgen games look bad from an light/shadow point of view. So if I were Kojima shadow artifacting is probably one of the first thing I would fix. Or even consider to remove self shadow as a whole.

And by the way what does the codemonkeys have to say bout mgs4 lighting/shadow is it regarded as good or bad?
 
AlStrong said:
I don't know if I'm allowed to say it outright... but there was a certain talk at GDC this year from a certain someone here. :p
Click to expand...


From you :?:

Can you please read the FAQ on posting style. We hold high standards, especially in the technology forum.
 
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muungano said:
From U:?:
Click to expand...

Nope :p

muungano said:
What are the problems with creating good shadows in consoles then. On a PC you had it for years, since hf2 (at least :0 ).
Click to expand...

Memory and filtering quality/speed, the interaction of the shadows in the scene with regards to dynamic light sources and self-shadowing, which wasn't in HL2 IIRC, just simpler pre-determined projected shadows.

Good and proper dynamic self-shadowing is a performance hog. You may want to check out nAo's and Andrew Laurenitzen's posts or threads in the other forums.
 
muungano said:
What are the problems with creating good shadows in consoles then. On a PC you had it for years, since hf2 (at least :0 ).

What makes out how large shadow maps one can use. And whar makes out the blur filtering. I mean from an art stand point I think that most nextgen games look bad from an light/shadow point of view. So if I were Kojima shadow artifacting is probably one of the first thing I would fix. Or even consider to remove self shadow as a whole.

And by the way what does the codemonkeys have to say bout mgs4 lighting/shadow is it regarded as good or bad?
Click to expand...

Well good looking dynamic shadows tend to require quite some rendering power, especially if they are soft. PC's are quite potent and thus why games come with high-res dynamic self-shadows and many tweak it beyond that level.
Though I agree with you that better to use pre-baked/no shadows than to have utterly low-res blocky, crawling shadows that dont resemble the shadow casting object at all.

I have bought CoD4 and AC (rebate mind you) and those 2 games have (for me as a PC gamer) ridicolous LOD levels for the shadows. Just 3-5 meters ahead and the shadows goes down to what seems like a 128*128 or 256*256 shadowmap... tssss the disappointment. :cry:
 
Nebula said:
Well good looking dynamic shadows tend to require quite some rendering power, especially if they are soft. PC's are quite potent and thus why games come with high-res dynamic self-shadows and many tweak it beyond that level.
Though I agree with you that better to use pre-baked/no shadows than to have utterly low-res blocky, crawling shadows that dont resemble the shadow casting object at all.

I have bought CoD4 and AC (rebate mind you) and those 2 games have (for me as a PC gamer) ridicolous LOD levels for the shadows. Just 3-5 meters ahead and the shadows goes down to what seems like a 128*128 or 256*256 shadowmap... tssss the disappointment. :cry:
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Yeah but he Cell should be able to some heavy rendering work right. Could it be a question of RAM or graphic card issue?

Good thing AC was on rebate since it´s the world most overrated game in history.(Could be an other thread UBIsoft graphics :cry: )

But how come then that RaCToD looks good and CoD4 don´t? Doesn´t RaC have dynamic shadowing, I thought so.
 
muungano said:
But how come then that RaCToD looks good and CoD4 don´t? Doesn´t RaC have dynamic shadowing, I thought so.
Click to expand...

RaC has barely any dynamic shadowing and less texture mapping than CoD4. I would think Cell can do quite some to help but I dont know how it would compete with a GPU regarding shadows. Also Cell has to do other things that are not graphic related and they cant devote all CPU time for graphic tasks.
 
muungano said:
But how come then that RaCToD looks good and CoD4 don´t? Doesn´t RaC have dynamic shadowing, I thought so.
Click to expand...
R&C has "artistic" shadows instead of "correct" shadows. You don't have everything casting shadows and characters don't usually shadow themselves or each other.

Sometimes this is good, though. R&C has a cartoonish look, so realistic shadows aren't necessary. Half-life 2 shadows are quite limited in realism too, but avoid artifacts.

Good shadows are a tough problem in realtime graphics. Fortunately, there have been some great developments recently that run extremely well on current PC GPUs.
 
Nebula said:
I would think Cell can do quite some to help but I dont know how it would compete with a GPU regarding shadows.
Click to expand...

Cell actually helps quite a bit with shadows, assuming you've reworked your engine to support it. For example, one pitfall when dealing with shadow passes is poor pre transform cache performance. Each vertex has a bunch of data typically assigned to it, and it usually sits in memory in an interleaved manner (position / uv / normal / tangent / etc). But when rendering the shadow passes, the only data you need is the position. So during shadow pass rendering, it gets a vertex position and then has to hop a large number of bytes to the next vertex position because they are spaced far apart in memory. This plays badly with cache, and hence you get stalls that can cost a lot of performance. With cell, you can keep one set of interleaved vertex data in memory as before, but rework it on the fly to create a more shadow pass friendly data set, with position data tightly packed together.

It can help with culling as well which is very important for shadows. I think Uncharted uses 5 parallel split shadow maps. This basically means it has to render the scene as seen from the light 5 times, albeit in simplified form (depth only). Still, thats a ton of culling, which you can have cell do for you ahead of time.

I haven't seen Metal Gear yet, but I'm surprised it has worse shadows than GTA4. Metal Gear has the added advantage of a sun that doesn't move so they can contain shadow performance even more compared to GTA4, which I believe has a moving sun. The problem with a moving sun is that when its low in the sky, it's view frustum hits a ton of shadow casting objects, which in turn means more performance issues. In Metal Gear then could just put the sun at a fixed position high in the sky, which would minimize how many shadow casters it would need to process.

Anyways, maybe nAo will chime in with thoughts, he's definitely a shadow expert.
 
Laa-Yosh said:
GTA4 shadows flicker a lot... probably a resolution issue...
Click to expand...
I'm yet to see a game that doesn't exhibit shadowmap resolution issues at times (even in Uncharted you can find it if you look hard enough).
That said - a nice fat filter kernel covers that up most of the time, and from what I understand, GTA is in a different league there.

Turok said:
Hehe, ever since I saw Doom 3 I assumed every game from then on would use stencil shadows.
Click to expand...
We might have seen more if PS3 had a different GPU :p But hw evolution pretty much made volumes obsolete before we even discuss the authoring and other problems they have.
Also amusing note, that Stencil Volumes were the most widespread (and efficient) on the console that had no hw support for them at all.
 
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