Are contact shadows really that important?

[Dr. Nick]

Currently I would say that it is necessary for a game to have shadows for the characters and objects projected on to surfaces like the ground and such. Self Shadowing doesn't seem to be as common as one would think it should be, like in everygame that has shadows, but one day with enough power backing it I think that it will become necessary for games that have the slightest bit of realism to have characters and objects with self shadowing.

The question I ask in the title of the thread is to find out if you guys think that contact shadows are just as important as self shadowing or simple shadows projected onto the ground. Currently in many of the games I play the characters and objects seem to kind of be floating against the background and don't seem to be really a part of the scene. I was wondering if contact shadows would fix this but the more I think about it the more unsure I am that it is the solution and that maybe there is something else that I'm missing. Maybe you guys can point it out for me. If we do reach the conclusion that it would fix the issue do you think it should be something for developers to pursue in the future? Now you might think that is a silly question but the fact is most games don't use them right now for whatever reason. So is it something to look forward to in the future that will end up being as common as the simple projected shadows? Is there something even better in the works than contact shadows and SSAO? Is SSDO even viable in a game on these high end video cards that are coming out today?

 

[semitope]

Some pics would be nice to illustrate.

btw this isn't realllly a technical topic is it?

 

[nightshade]

Having SSAO is always good, but having it with poor artifacts is not very good as in case with Gears of War 2...where the SSAO fades away when you are in motion & atleast takes .5 to 1 second after you have stopped to get into process.Another poor example of Self Shadowing going wrong is the PC port of Red Faction where the contact shadows are just blurry & dithered and they make a huge impact on performance too.

IMO it totally depends on the game, tittles like Batman AA [PS3] can get away without any kind of AO because of the darker color palette but at the same time tittles like Resistance 2 look horribly bad in places & you would think that having SSAO in that place would've been so much better.

 

[Graham]

It's ironic that (in my opinion) the best implementation of SSAO remains the first: Crysis. Crytek's implementation was done with subtlety and only affected ambient lighting. You didn't notice it was there, but you would notice it it wasn't there.

Too many games use SSAO to darken all lighting, not just indirect lighting. And they use either a small radius (producing noticeable edge 'burn') or simply apply the effect far too heavily.

Gears 2, while implemented very intelligently (using re-projection for temporal coherence), was applied far too strongly - and was applied to all lighting. So the baked light maps already had their own AO, however you had this fake AO on top - which looked clearly out of place.

It reminded me of what happens when 'HDR photography' goes bad. You basically end up with loads of local contrast, but no overall areas of light/dark - resulting an overall washed out and gray look. Of course, lightmass seems to do a very good job of fixing this.

 

[Shifty Geezer]

Too many games use SSAO to darken all lighting, not just indirect lighting. And they use either a small radius (producing noticeable edge 'burn') or simply apply the effect far too heavily.

That's true. AO needs to be subtle to work, otherwise it looks like a dark halo. When it's good, SSAO can be surprisingly good, but I don't think many devs pull it off that well at the moment.

 

[Mobius1aic]

That's true. AO needs to be subtle to work, otherwise it looks like a dark halo. When it's good, SSAO can be surprisingly good, but I don't think many devs pull it off that well at the moment.

Crysis, UC2, Far Cry 2, and FEAR 2 do a decent job with it.

 

[PhilB]

I do believe Far Cry 2 doesn't use SSAO unless you're playing the PC ver with NV AO. Fear 2 in my opinion has by default the worst attempt at AO I've seen. The best I've seen is probably STALKERs hbao - fast, acts right and generally devoid of artifacts. If every game could do something like it I wouldn't mind. Stuff like Fear 2 though really just detracts from IQ and probably better off without it.

 

[nightshade]

For me the best implementation of SSAO were in UC2,Crysis & like Phil said STALKER's HBAO looks pretty solid with minimal artifacting as well

 

[Laa-Yosh]

One more thing for contact shadows: outdoor daytime areas usually only have one shadow casting light source, the sun. So once you move into an area that's shadowed by a building, a large cliff, or anything, then you completely loose shadows and their effect of integrating objects into their environment; everything will look a bit like it's floating above the ground. Contact shadows and/or fake AO can help this problem significantly.

 

[Shifty Geezer]

Crysis, UC2, Far Cry 2, and FEAR 2 do a decent job with it.

U2 is certainly hit and miss. I recall one ocassion of the characters tanding near a door and they just appeared to be surrounded by a dirty halo rather than be occluding light. I think the 'penumbra' (don't think that's the right word) wasn't diffuse enough. But at other times it's exceptional and produces some very convincing depth.

 

[zed]

Having SSAO is always good

Debatable
it looks good always in the greyscale images i.e. SSAO only
But once u add the diffuse image in often its hardly makes a difference, though u certainly notice the difference in framerate though.
little big planet would be the best implementation by head and shoulders (then again are they doing it with game?)

 

[Shifty Geezer]

Media Molecule aren't using SSAO, but irradiance slices. If you switch off the main light and just use point/beam lights, the AO type shading isn't applied on these and the end result is harsh direct lighting. In my Oonoi level, I have lots of hidden fill lights to provide uplighting etc. and add depth to the illumination.

 

[Mobius1aic]

I do believe Far Cry 2 doesn't use SSAO unless you're playing the PC ver with NV AO. Fear 2 in my opinion has by default the worst attempt at AO I've seen. The best I've seen is probably STALKERs hbao - fast, acts right and generally devoid of artifacts. If every game could do something like it I wouldn't mind. Stuff like Fear 2 though really just detracts from IQ and probably better off without it.

My problem with FEAR 2's SSAO is how it gives the game an overly soft look that I think detracted from what I expected FEAR 2 to look like, considering the first FEAR, of course didn't have it. As for NV AO on FC2, I'm pretty sure it was being used when I was running it on my laptop. I think I specifically remember it not being there when running it in WinXP on my desktop which had an ATi 4670 at the time. This was about a couple weeks ago. Is it a DX10 only feature in FC2 or is it available via DX9 as well? I only just procured Windows 7 today as a matter in fact :smile:

 

[homerdog]

As for NV AO on FC2, I'm pretty sure it was being used when I was running it on my laptop. I think I specifically remember it not being there when running it in WinXP on my desktop which had an ATi 4670 at the time. This was about a couple weeks ago. Is it a DX10 only feature in FC2 or is it available via DX9 as well? I only just procured Windows 7 today as a matter in fact :smile:

I don't think it's locked to DX10.

In any case it won't be used unless you force it through the control panel.

Debatable
it looks good always in the greyscale images i.e. SSAO only
But once u add the diffuse image in often its hardly makes a difference, though u certainly notice the difference in framerate though.

You may not notice it in screenshots (debatable), but the whole point is to have a decent realtime solution for indirect lighting. At the moment SSAO seems to be the only game in town, and it's miles better than no indirect lighting simulation at all IMHO.

 

[Neb]

At the moment SSAO seems to be the only game in town, and it's miles better than no indirect lighting simulation at all IMHO.

I dont think anyone sane would dispute this until other better method is doable in realtime. Either baked in AO or realtime SSAO it makes a world of difference. Just imagine Fallout 3 without baked in AO..uhhhh. And swtiching it on/off in Crysis games makes you know why you never would want to turn it off. Subtle but does so much and as said the most impressive implementation and results in a game (I'll guard my back by saying I haven't played games with HDAO so far).

 

[zed]

Media Molecule aren't using SSAO, but irradiance slices. If you switch off the main light and just use point/beam lights, the AO type shading isn't applied on these and the end result is harsh direct lighting. In my Oonoi level, I have lots of hidden fill lights to provide uplighting etc. and add depth to the illumination.

thanks I forgot, yes I thought the lighting was much higher quality than SSAO

You may not notice it in screenshots (debatable), but the whole point is to have a decent realtime solution for indirect lighting. At the moment SSAO seems to be the only game in town, and it's miles better than no indirect lighting simulation at all IMHO.

Well if u cant notice it in screenshots u cant notice it fullstop (though since its a framebuffer FX it does show aliasing with movement), though I think u misunderstand me, IMO the performance cost vs the image improvement makes it debatable wether or not to use it.
I myself ditched it in a recent program cause of the ~30% drop in FPS

 

[Neb]

IMO the performance cost vs the image improvement makes it debatable wether or not to use it.
I myself ditched it in a recent program cause of the ~30% drop in FPS

In Crysis/Warhead/Crysis Wars it has only an impact of a couple of frames ~5-10% or less.

 

[homerdog]

Well if u cant notice it in screenshots u cant notice it fullstop (though since its a framebuffer FX it does show aliasing with movement), though I think u misunderstand me, IMO the performance cost vs the image improvement makes it debatable wether or not to use it.
I myself ditched it in a recent program cause of the ~30% drop in FPS

Yes I must've misunderstood. But like Neb said, in Crysis (probably the best SSAO implementation yet) the perf hit is barely noticeable on decent hardware. Of course I understand other games can be worse about it.

Which game was causing the 30% drop if you don't mind my asking?

 

[Silent_Buddha]

Added to all that HDAO using CS 5.0 in Dx11 is pretty fast. Battleforge is pretty impressive in that aspect.

Regards,
SB

 

[nightshade]

As for NV AO on FC2, I'm pretty sure it was being used when I was running it on my laptop. I think I specifically remember it not being there when running it in WinXP on my desktop which had an ATi 4670 at the time. This was about a couple weeks ago. Is it a DX10 only feature in FC2 or is it available via DX9 as well? I only just procured Windows 7 today as a matter in fact :smile:

I think the game itself supports AO cause I remember the visual setting having AO option...& that was when I played on XP.