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Atlas LOD issue - holes and chunk edges

by Arcanor · in Torque Game Engine Advanced · 10/18/2007 (1:06 pm) · 3 replies

Under TGEA 1.0.3, and terrain designed and exported using L3DT.

As you can see from these screenshots, I'm having a problem with atlas2 terrain. When I'm far away from a chunk boundary, there are some parts of the map where the terrain has a "depression" that is getting smoothed out by LOD calculations, i.e. vertices are being removed. This has the effect of "pushing up" the front edge of the distant chunk, so I can sometimes even see through the terrain completely.

Here's how it looks from far away, the LOD is kicking in fully:

www.arcanoria.com/tmp/terrain%20LOD%20error%20-%20far.jpg
Here's how it looks from a moderate distance. You can see that the "gap" is beginning to close up.

www.arcanoria.com/tmp/terrain%20LOD%20error%20-%20medium.jpg
Here's how it looks from nearby the chunk boundary. There's no error at all.

www.arcanoria.com/tmp/terrain%20LOD%20error%20-%20near.jpg
Anyone have any ideas about what can be done here? Has anyone seen this before?

Thanks in advance.
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Torque 3D Owner J.C. Smith
#1
10/18/2007 (2:02 pm)
You can try lowering your error metric, but they seem to be pretty common. I just try to get as few as possible when balancing my error metric, and then cover them up with dts objects or interiors.

Torque Owner Arcanor
#2
10/18/2007 (6:00 pm)
When you say "lowering your error metric" I'm not sure what you mean. Are you speaking of the Atlas advanced options dialog when doing an atlas export, in the geometryErrorThreshold field? This is currently set to 2.000000. If this is the correct field, what sort of guidelines are there for adjusting the value?

Thanks!

Torque 3D Owner Mark Dynna
#3
10/18/2007 (6:23 pm)
A good starting value is %1 the size of your map. Make successive export attempts, lowering the error each time, until you find the point where you overflow the verts/chunk limit. That's the point where you have effectively "maxed out" the level of detail possible with your geometry.