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Game mapping: What is a useful size? Polycount etc.

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Game mapping: What is a useful size? Polycount etc.

Postby Rmorph » Sun Apr 09, 2006 6:56 pm

Hi,

Sorry if these questions are a bit noob :-)

I know this is a difficult question to answer (subjective to speed, etc) but I am having a hard time with scaling (metres vs pixels etc):
I was just wondering, what is a useful size to export maps as for a 3d game? I am exporting to Terrangen (ter) format, and then importing into (primarily) blender? I am looking to make maps of the same basic size as for example world of warcraft. I am looking for a good balance between features and scale versus polycount. Obviously the larger maps will look gorgeous: but at significant polygon counts. I would like to strike a balance that I can use as a standard format for zone generation. Anyone else out there already thought this one through?

On a related matter: Is there a way to reduce polygon count in the L3DT program? Or set a max poly count?
Obviously maps with 100s of 1000s of polygons are a bit overkill, especially for plains, seabeds etc.



Secondly (and it might just be me) There seems to be some formatting issue where blender converts the scale to something quite small on output so that the terrain is just a small square.
I see that terragen does not seem to support the same large sizes as L3DT (hence the "L" in L3DT I guess). Is this an issue with Terragen formats then? or should I just make the maps smaller to begin with in L3DT (default to terragens maximum size).

Thanks for any responses.

Mike in Norway.
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Postby Aaron » Wed Apr 19, 2006 9:10 am

Hi Mike,

Sorry for the slow reply; I was kind of hoping a game-developer in the community might have something to say here, but alas.

Rmorph wrote:I was just wondering, what is a useful size to export maps as for a 3d game?


Hmmm...that's a tricky one. The short answer is I don’t know. The long answer is I think it depends on your rendering-system (level-of-detail, etc), how much RAM / hard-disk you’re willing to burn, what sort of compression you use to store the data, whether you use an optimised mesh or a heightfield to store the terrain, etc. Basically, I’d recommend working out your rendering system and then see how may bits you can pack-in before the performance suffers.

That's not a very useful answer, I’m afraid, but I'm not really a game-programmer. This might be a good question for gamedev.net, I suppose.

Rmorph wrote:On a related matter: Is there a way to reduce polygon count in the L3DT program? Or set a max poly count? Obviously maps with 100s of 1000s of polygons are a bit overkill, especially for plains, seabeds etc.


L3DT uses raster-data rather than mesh-data, so there are no ‘polygons’ as such. If you want an optimised mesh with a reduced polycount you’ll need to import it into a 3D-modelling program (eg. 3D Studio Max) and do the optimisation there. L3DT exports the heightfield as a .x file, which 3DS Max can read.

Rmorph wrote:Secondly (and it might just be me) There seems to be some formatting issue where blender converts the scale to something quite small on output so that the terrain is just a small square. I see that terragen does not seem to support the same large sizes as L3DT (hence the "L" in L3DT I guess). Is this an issue with Terragen formats then? or should I just make the maps smaller to begin with in L3DT (default to terragens maximum size).


Hmmm...I’ve never played with Blender, so I can’t help with that. Help, anybody?

As for the TER format itself, it really depends on the implementation of the reader/writer in the relevant programs. There is some funny business with the multiple, redundant scales defined in TER files, but a sensible reader/writer shouldn't have a problem. As far as I know, L3DT's TER files are kosher (well, no-one has told me otherwise yet).

Cheers,
Aaron.
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Postby demi » Sun Apr 23, 2006 4:44 pm

Hi Rmorph,

I been using Blender but I do it with .x because the ter to Blend is a pain in the butt since it tends to loose scaling. Get the directx import/export plugin from the Blender site.

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Postby Joshua » Tue May 16, 2006 12:27 am

Rmorph, one thing I wanted to clear up:

It sounds as if you're going to be using the exported maps in your engine as meshes exported from Blender? If this is the case I would recommend you look into displacement mapping instead, and import the exported terrain image files directly into your engine.

You'll need to use optimization techniques such as horizon and standard hardware culling as well as a functional LOD algorithm that takes more than just distance into play (roughness and complexity of areas of terrain). On top of this you'll probably want to implement geomorphing of the terrain so that each LOD level of the runtime mesh created will blend into the next for smooth transitions.
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Postby trollfiddler » Tue May 16, 2006 12:36 pm

Yep, a lot of this depends on your engine. Torque Shader Engine for example uses paged terrains and LODs automatically for very fast rendering of massive terrains. The size and complexity of the terrain is limited only by your disk space. It has little effect on rendering unless you have a slow machine and set a long viewing distance. Of course, once you start adding trees, grass, enemies and stuff like that you start to slow down. But your engine should be capable of rendering empty terrain pretty efficiently.

L3DT produces gorgeous detailed scenery that doesn't even make Torque blink on my machine.
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Postby TheMeatMan » Tue May 16, 2006 8:33 pm

I have used various terrain rendering techniques: ROAM with morphing vertices, quadtree techniques with morphing vertices, geomipmap, and straight triangle strips. I have found that triangle strips are the fastest, especially with newer video cards. But then again, I was using the fixed function pipeline, so it would be interesting to see things like ROAM implemented within the GPU via a shader. This was work that I have done at my day job (military sims). Cannot wait to get my hands on a Pro lic. of L3DT (if I am deemed worthy that is!).

I have a license for the TGE & TSE too, but I stopped using them because the type of game that I am trying to do would have required so much rework of either engine, I figured the effort to write specialized game code (not an extensible engine) that focuses on my game was the way to go. I just got the PhysX SDK and am looking at using Raknet for the networking piece. Not that what the folks at GarageGames are doing doing anything wrong by any means, it is just a matter of the right tool for the right job.
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Postby Joshua » Tue May 16, 2006 8:46 pm

For physics and collision detection, I'd recommend Newton Dynamics, if you haven't already checked it out. It has the additional bonus of being free. :wink:
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Postby trollfiddler » Wed May 17, 2006 8:34 am

@TheMeatMan,

Yep, I agree, use the right tool for the job, it always makes things easier.

In my case I tried many other engines/SDKs, some low level, some high. They supported various programming languages from Basic to Java to C++. In the end TSE was right for me as I'm writing a first person RPG, and there's plenty of support in the product (and in community resources) for that.

T.
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