Lod

RoyGBiv

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some gifs of LOD. even when i watched the video for the first time the LOD popped out to me in two places. i made 3 gifs to show where the LOD is. and since the videos are suppose to be a new build then this is what you should expect. one is the city battle scene and the other is the jail scene.
 

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so where are u getting at?

we already knew that HL2 would have a huge level of detail...
 
yeah, just showing what it looked like from what we have available.
 
Hey nice find. It doesn't actually have to do much on a card like that tho ^_^ but still a good indication.
 
i'm sorry.. but what are we looking at exactly? :eek:

ohhhhh now i see it..
 
I'm not sure that's an LOD issue. It looks more like a texture error when I frame by frame the vids (there's also one in the tech demo) I mean, if it was LOD (which is supposedly used heavily), we'd be noticing it everywhere, not just in one or two very obvious places. Also, while the main engine development is done, that doesn't mean they aren't tweaking it to correct bugs and such. What they've stopped is the addition of new features.
 
LOD stands for level of detail. It means scalable level of detail. As you get closer, things become more detailed. It means you can have large outdoor (or indoor!) areas without slowdown, as distant objects are drawn at very low detail. Visual quality isn't compromised, if things are far enough away for the level of detail to be scaled down you can't really see the detail anyway.

A good example of an LOD system is Black&White. It featured really big outdoor areas! As the camera zoomed out the number of polygons used to draw the landscape reduced as did the texture resolution.

Up until now most FPS games only scaled textures with distance. I hope those images represent a real polygon LOD system rather than rendering artifiacts.
 
As I watched these it becomes clear that they are infact LOD level changes for sure. in the first one you can see the line where the seam of 2 polys flips and moves. inanother you can see the objects eng grow and get more detailed.
Question is now, is the LOD geometry generated by the engine, is it done by the modeler, or is it done to each model while compiling the level?
Being an old school Flight Sim Toolkit user I'm a bit partial Myself to doing all the LOD stuff Myself to My models when I build them, and tweaking the distance settings untill its just right. Its a lot of extra work, but it can also look better than the engine doing it all and should be a lot less overhead for the CPU.

Nice find on noticing these.

One other thing I noticed in your pics that would suggest LOD. It is only happening to "objects" which may just be imported models and not world geometry brushes.

The Punisher
 
Actually that's a really good point derby. I remember playing B&W on my Celeron 366 w/ TNT2 and it ran beautifully. Also about the scalability thing they WERE using a mint machine so I don't think it would've been necessary :/
 
As I watched these it becomes clear that they are infact LOD level changes for sure. in the first one you can see the line where the seam of 2 polys flips and moves.

I disagree. From watching the vids over and over, and the actual frames that are side by side, it still could be a lighting/texture artifact. Check out the board in the tech demo: same startling instant change from one texture to another on a piece of splintered wood. Why would the LOD engine do that when you are right next to it?

As I said, if it's LOD, then why aren't we seeing things "popping" all over the place?
 
well i made them from the gamespot and 500mb videos. the 500 one is the first gif that has 3 frames. and you can tell that something obvious is changing in that one.
 
disagree. From watching the vids over and over, and the actual frames that are side by side, it still could be a lighting/texture artifact. Check out the board in the tech demo: same startling instant change from one texture to another on a piece of splintered wood. Why would the LOD engine do that when you are right next to it?

I think you ARE seeing texture changes here, but I believe theres also a geometry change going on at the same time. I think the reason you arent seeing things poping up all over the place is that in most cases they did alot better job on the LOD distance setting and matching goemetry fome one level to the next.
I'm sure hoping thats whats going on, because if it is then that will possibly mean that we can get more carried away with the up close deatil of our models and still get good framerates in large open maps as well.
Geometry LOD is something thats been used in some flight sims for ages, when properly done you wont be able to notice the lod changes because they should take place far enough away that you cant detect the change. Some argue that it isnt nessesary on a FPS, but I think didtance is all relevent. You should never be trying to force the engine to draw multiple polys that are smaller than one pixel on youre monitor, its a waste.

Of course this is all just speculation at this point, were all just wizzin in the wind untill we got more confirmed details.
 
Here's My main reason for thinking that we are seeing an LOD level change.

Look at the red line I have drawn at top edge of the closer of the 2 beams
 
LOD is done by the coder/designer usually.

That is a good example of LOD in those gif files (it's not just texture errors or whatever that guy said, you can see the model changing slightly). It's like in say... Homeworld, when you're far away from your ship it's just a box, then you get in closer and it's a far more detailed shape. Just so it doesn't use as much graphics power when it's far away, because you can't tell the difference anyway. But when it's used poorly so you can see it changing (easily) then it kinda sucks.

Also, AI can be LOD'd, so when you're far away they just walk in a stupid circle, but when you get closer, they react to things and do different things (not just because your character is near them)
You can see this by looking through the sniper rifle at really far away enemies. It saves CPU cycles I guess.


I think Vice City had some of this in it from my playing experience.

The best way to us LOD is to hide it as well as possible.
Or get to a point when power isn't an issue, and there's no need for LOD.
 
Originally posted by Wesisapie


Also, AI can be LOD'd, so when you're far away they just walk in a stupid circle, but when you get closer, they react to things and do different things (not just because your character is near them)
You can see this by looking through the sniper rifle at really far away enemies. It saves CPU cycles I guess.


I think Vice City had some of this in it from my playing experience.

The best way to us LOD is to hide it as well as possible.
Or get to a point when power isn't an issue, and there's no need for LOD.

Top part, with AI, you could see in Morrowind, NPC would just stand there like trees, but when you would come closer, they would move. Anyway, and in my opinion GTA3\Vice City did horribly LOD, you could see these buildings changing on your eyes, not a plus. I think when you were on the helicopter, you could see them clearly (low poly models and washed out textures).
 
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