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[SOLVED] Cracks in terrain


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Ok, i know there have been several other threads about cracks in terrain, however this case is not the same as those raised before i believe.

 

The cracks are not at the edge of 2 terrain tiles - this is on a single terrain tile.

 

It is not at a LOD level change - Take a look at the screen shot supplied, the LOD setting for all terrains in our world is 45, but changing this even to 100 does not solve the problem.

 

I can remove it by editing heights - example by using the terrain heights or smooth brush across the crack. This is not an acceptable fix as it means we have to search our whole huge world for the cracks and then they just seem to randomly come back in another location anyway.

 

We are using a double proecion build of Unigine and our world size is very large (roughly 270km long, with many terrain tiles)

 

The tile is located at 633724.0,6539281.0,-12.100 in the world, so as you can see a long way from the origin.  I am suspecting a precision problem with the terrain?

 

It would be very hard to supply a test case example.

 

 

post-158-0-40683500-1363838036_thumb.jpg

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Can i get some comment on this please unigine team? this is a major bug on a project due to be delivered to a customer very soon.

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Shane and Anton,

 

It is not at a LOD level change - Take a look at the screen shot supplied, the LOD setting for all terrains in our world is 45, but changing this even to 100 does not solve the problem.

That could be a crack between two LODs - if the LOD distance is set very close. And in this case, setting higher LOD distance helps.

 

However, since you say that changing the LOD distance does not affect it (at all? does it change its position?), I'm afraid we'll need a test scene. Never encountered such bug on our side.

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We had several cracks in the terrain too how I fix it is by exporting the current heightmap and then re-importing that heightmap on the terrain it usually fixes it

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This old post just came to my mind and I can remember that I had a look in the ObjectTerrain source code and was unsure if all the local space transformations still done in float could somehow exceed float precision range in case of tiles really far away from the origin. Maybe a starting point for re-evaluation of above problems.   

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It might depend on the size of the terrain, as all calculations are done relative to one ObjectTerrain corner. How large is the size of your terrain km x km ?

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8km*8km

 

Well, with this size your crack problem is most likely not related to any float precision limit. Nevertheless in Shane's case with terrain sizes of several hundred km this is still a premium candidate.

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Shane and Anton,

Could you provide us a test scenes for reproducing this issue.

We can't reproduce this behaviour and a test scene would be really useful for us.

 

Thanks in advance

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  • 2 weeks later...

I have found the crack appears between surfaces viewed at any distance- I tried to put a test case together however it is too large (70mb zipped)

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  • 1 month later...
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