Terrain and background objects

[zingbat]

Can we do something like this easly ? Notice the terrain is heavly LODed. The question is if we want to use, possibly animated, background objects like the ones in the picture (those were put there with a paint program by me) how do we make it work with the terrain lod algorithm ?

http://elander.no.sapo.pt/_tower.jpg

Another situation is when player is traveling and the object is visible outside the scene range (the object is still a background object). At a certain moment the object enters the scene range and the background object is replaced by a scene object with collision, AI info, physics info, rooms stuff inside, etc… What problems can happen in this situation and is there an easy way to solve them ? Thanks.

[cfmdobbie]

Ah, Oblivion! ;D

Firstly a few words of caution: that game has been in development for over three years already. It isn’t likely to be released for another year to a year-and-a-half so won’t be expected to run on much less than a 3-4GHz PC. Also, note that the linked image has been described as an “in-game screenshot”, a “cut-scene screenshot”, and also as “concept art” - so exactly how much of that image is an accurate representation of their current technology is anyone’s guess!

But moving on, I agree - that background looks static to me. There definitely appears to be some serious LODding of the trees, but how much of that is down to JPEG artifacting, I don’t know.

From what I can see, games are trying to move entirely away from the “cell loading” problem, and as that was so heavily criticised in Morrowind, I expect Oblivion will use some kind of continuous streaming of data. Note that this just means you have a continuous stream of visibility issues rather than a big block of them at once!

The biggest problem with LOD systems is when the low-detail representations (of textures, meshes, sometimes even sounds) differ significantly from reality. The two main ways to deal with this are: firstly, to make sure your low-detail data closely follows the high-detail data; secondly, to handle the differences gracefully. Clever people have implemented LOD systems where high-detail meshes exactly match low-detail meshes at the point of coming into range, but rapidly morph into the “proper” data as time goes on.

Another issue with LOD is that it assumes that everything past a certain point is largely irrelevant and to be ignored. If you have interesting details a long distance away that are likely to attract attention, then performing any viable LOD on them becomes a knotty problem. The usual approach, I believe, is to give up.

EDIT: In case anyone’s interested, the original graphic can be viewed here.

[zingbat]

Also, note that the linked image has been described as an “in-game screenshot”, a “cut-scene screenshot”, and also as “concept art” - so exactly how much of that image is an accurate representation of their current technology is anyone’s guess!

They have already comfirmed the screenies are in-game shots in the forum and in the FAQ in the main site. One of the devs mentioned in the forum the last Radeon model to develop the game.

But moving on, I agree - that background looks static to me. There definitely appears to be some serious LODding of the trees, but how much of that is down to JPEG artifacting, I don’t know.

Ah yes. Sorry about that. These are the original screens:

Elder Scrolls

From what I can see, games are trying to move entirely away from the “cell loading” problem, and as that was so heavily criticised in Morrowind, I expect Oblivion will use some kind of continuous streaming of data. Note that this just means you have a continuous stream of visibility issues rather than a big block of them at once!

That usually looks a lot better than the cell way. Gothic2 has issues too even if the LOD system is far more efficient than Morrowind one.

Another issue with LOD is that it assumes that everything past a certain point is largely irrelevant and to be ignored.

Background objects are very important for me. They enhance gameplay imesurably. The detail of a structure in the background (animated if possible) is much more important than just another crate or tree. It plays an important rule in the game. I think that even with a little artifact showing (probably at the moment the object switches from the background scene to the active scene) this feature is very valuable for gameplay.

[divzero]

Regarding objects which you don’t want ignored, those objects can simply have a different LOD policy to the rest. I am implementing this soon in my game, where the important objects reduce their detail at much greater distances and never dissappear, and less important objects reduce their details sooner and are removed at great distances.

Will.

[zingbat]

You are are talking of Tank Commander III right ? What kind of objects are you thinking about using for background references ? I would think about what was the feeling of the world where the battles are taking place and decide from there.

For example on an heavy battle the player would see traces of bombers in the sky and explosions here and there all ocurring at random. At a certain moment one of these background objects would start falling and crashing very near the players tank location. The tricky part for me is how to make this happen so that the player doesn’t see the LOD transitions.