June update + Antialiasing glitch

Ross Scott

Ross Scott

Staff member
Well I've been getting some requests for updates. I haven't posted more because the situation is still the same; I'm still busy on the next CP episode and the website is still in development. I know It might seem like I'm not doing anything, but I've actually been making a lot of progress; it's just an inherently slow process to produce episodes at the quality level I strive for in Civil Protection. Each episode is much more than just recording and editing, it's more like a minature mod for the game.

On that note, I've been getting pressure on all sides to produce more episodes of Freeman's Mind. I'm still not producing any more until I finish the current CP episode, but after that, I may alter my plans to make it first priority and have them come up at a much more rapid rate. Many of you have said you prefer it over Civil Protection. I think you're only saying that because you don't know everything I have envisioned for the series. My imagination far exceeds my production capacity. On that same note however, I'm not even attempting the "jaw dropping" episodes in the near future because of how much more work they would entail. So due to the time involved with making those, I'll probably focus on easier projects, like FM. In the meantime, I'll continue blazing away on the next episode.

The next part of this post only applies to 3D graphics geeks, so you can skip it if you're just here for the videos. The glitch I'm listing below will NOT hold up production on the next episode.

- - - - - - - - - 

I've run into a minor nuisance in production that simply hasn't gone away. I'm a sucker for antialiasing; I think it cleans up the look of a 3D scene immensely. However I've gone through multiple generations of graphics cards and keep running into the same glitch when I enable antialiasing. For lack of a better term, I'm calling it "shimmering". This glitch seems to be especially noticeable in the Source engine in certain situations. It's similar to looking at a road in the distance on a hot day, giving the illusion of a puddle. It causes lines or gaps or something to be rendered that should not be there. It only happens for me for surfaces in the distance with antialiasing enabled. It's best seen in motion, but it's noticeable in screenshots. I recommend downloading "On A Rail" if you want to see it in action. Here is an example where it occurs from that video:

http://www.radford.edu/~rscott31/onarailshimmer.jpg

That's not just a reflection from the lights, this glitch occurs in 100% dark tunnels. While I'm on a Geforce 8800 right now, this has happened to me on multiple cards in the past and I've witnessed it happening on a friend's computer with a Radeon 4850. The ONLY solution I've found to this is to either turn off antialiasing completely or to render the scene using supersampling entirely; no multisampling whatsoever. This is not an ideal solution as supersampling is immensely slower and requires too much memory to hit the same quality levels as other antialiasing methods. If ANYONE knows what's causing this or can demonstrate a solution, please contact me at [email protected] or post here.

Feel free to test this for yourself! If you have a copy of Half-Life 2, a good spot to test this is on the first canal level (d1_canals_01) looking back at the dark train tunnel you see once you get outside. Here's an example of the effect for that level:

http://www.radford.edu/~rscott31/d1_canals_01.jpg

If this problem doesn't affect you, great, but I'm trying to find out WHY. Ask people who know a lot about 3D graphics. Ask ATI. Ask Nvidia. Ask on tech forums, it'll be a favor to me. Again, this glitch won't hold up production of any episodes, it's just a personal quest of mine to find out how to fix it and I'm hoping someone out there knows more about it than I do.

EDIT:

Viewer Carl Johnson (not the one from Grand Theft Auto) has made me aware that disabling AA and AF through the driver control panel, then setting the AA settings in-game will prevent this problem on ATI cards. Unfortunately I tried this and it didn't seem to have the same effect for me (since I'm currently on an Nvidia one), but that's encouraging to know this is fixable.

 
Finally an update

Im really excited for the new cp episode...But im seeing forward to fm too.

 
It's almost certainly showing up at a seam between two polygons (bear in mind that brushes get chopped up every 1024 units when the map is compiled). Am I right when I say that it only appears on ceilings?

 
AA issues have been my pet peeve since I first switched to nVidia cards over ATI's. Seems to be some sort of quirk on Source's end...

Seems like Z-Buffer or Occlusion Culling going mad, but I'm no expert on these thing... I think switching to really high AA (16x or whatever) cures a lot of these glitches though.

 
Thanks for the update again Ross. Best of luck.

Yes, I check your page frequently.

 
hmm, dont think ive run into this glitch personally, but then again i havent played for a while and never looked too closely at ceilings in tunnels... ill have to check it out.

thanks for the update though, always nice to hear from you.

 
Tom Edwards: No, I'm afraid you're not. This appears on the ground and walls too. It's also not a point where there's a seam (within Hammer anyway). It can be a perfectly solid brush and the effect is ongoing (not just in one area).

fire.esper: I actually didn't have this particular problem on my old X800, but that had a different visual problem. Both ATI and Nvidia seem to have this problem now. As far as pushing AA to extremes, no, it does NOT cure this particular glitch. The only solution I've seen is PURE supersampling AA and even then, that's capped at 4x and slow as glue.

 
Looks to me like the game is fine. If its an npc on the train then thats why.

 
It might be a solid brush in Hammer, but VBSP will have chopped it up if it's too big. Use mat_wireframe to examine what's happened in-game.

BTW, have you experimented with AF at all?

 
i dont know if it will help but iv got a nevida 9800 and i havent seen it happen to me so try that

 
Maybe theres a glitch where it super enhances normal backround light (eg. sunlight) to where it just comes through whatever. Similar to what you said about glimmers on roads too far away, but imagine if it was on a lighter surface (such as sand). There'd be glimmers, and glares from combined light bouncing back at you at that angle. As the angle gets lower relative to long surfaces, all the light from those angles are closer together and therefor "brighter". Maybe the renderer does this to an extreme and it just phases through materials once they arent in the vicinity.

 
AK-47

I havd seen many similar anti alising problems in other programs

Bryce 3D defenetly has it on lower sampling rate. Poser, Blender, 3dsmax,Vue 6, Cinima 4d all have some anti alising problems and boostiong sample rate helps but EATS UP A LOT OF RENDER TIME. So AA itself is troubeslome

So I basically photoshop those pixels.

Also , in this case I think it is just a general problem of pixels not acting correctly. In games there are a lot of tricks to simulate light and shadow by baking, faking, and shaking

But anti alising is more or less linear and light bases effect. So when many of the shortcuts they take to make lights,lamps,water and such intareact with the AA process, some artifacts arise.

And this deffientyl a softweare and not hardware issue. I rendered same image in bryce on totaly differnt machines with same effect.

My advice.. render the scene with and without AA, and then put a small mask over the area to revial the non AA part bellow.

that may seem crude, but in production similar tricks are used all the time, like camera projections for example

 
I'm getting weird graphical glitches in Team Fortress 2. They usually only appear when i have AA and Anisotropic filtering on.

 
Slow as glue? Your crazy...

Anyway, I keep AA turned off at all times due to slowdown(my computer sucks ass) but I know my friend gets this and a few screenshot from google images have this glitch.

 
I'll tell you one thing,

It's a commmon problem, there are things called PATCHES.

 
Tom Edwards: Well I can't tell because it's always at a distance when this happens, it never occurs close up. I'm still hesitant to believe this for two reasons:

1. It looks continual, not in one spot. It would have to be splitting the brush up every 4-8 units or so.

2. I've seen this happen in at least one non-Source game, it was far more extreme in that. Again, supersampling was the only way to solve it.

Yes, I have experimented with AF and practically every feature nHancer has to offer. It seems to make no difference.

Matt L.: I have no idea, but I doubt it's just Source. If it was the engine, it seems like this would happen in all situations, not just multisampling.

AK-47: I don't know about it being strictly software. This problem literally did not exist on my old x800, (although that did have a problem with actual seams, some sort of rounding error maybe). My conspiracy theory answer is that ATI/Nvidia are cutting corners on graphics quality to get more speed and in the majority of games this simply isn't noticeable.

Your solution would probably work, but that's too extreme for me. It's easier to just stick with the more reliable supersampling, even if it does make everything chug all to hell (and stay capped at 4x). That's only an option on Nvidia cards, and even then, only for Direct3D. It just seems insane to me as much money goes into making these cards we can't do AA properly.

Anonymous: Except for "Friday" my episodes are always completely smooth because I do frame by frame rendering so I never drop frames. The viewer doesn't see how slow things actually move when I'm recording. Believe me, some episodes CRAWLED.

 
i am not a great machimimator or anything but i might have a simple solution for this,

put the charachters in front of it, use angles that dont show as much of the back, and mabye just a bit of photodoctoring to cover it up with similar surrounding colors or just simply put something black in the backround just far enough so you dont see any of the material.

i might also suggest making it look caved in (because of a RAS) and use that as an excuse to keep it in the background

 
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