[Opensim-dev] DEM -> Raw

[dan miller]

I know I've been out of the loop for a while, but I think it's worth noting that last I looked at terrain, there was an odd issue.

The terrain maps are 256x256, but to generate accurate terrain with interpolation across a 256x256 region, you actually need 257 x 257 numbers.  Otherwise, you can't properly interpolate one column and one row.  If you have access to the adjacent region's data, you could use that, but in general I don't think that's possible (certainly not in grid mode).

When I looked at this late last year, I seem to recall that the rendering software and the physics both did funny things along two borders because of this issue.  Just a heads-up in case anyone is looking into it.


-danx0r


--- On Sat, 5/24/08, Frisby, Adam <adam at deepthink.com.au> wrote:

> From: Frisby, Adam <adam at deepthink.com.au>
> Subject: Re: [Opensim-dev] DEM -> Raw
> To: opensim-dev at lists.berlios.de
> Date: Saturday, May 24, 2008, 3:32 PM
> Formats are:
> 
>  
> 
> RAW = LLRAW (documented on the SL wiki) - terrible format
> best avoided
> unless you want to have artists edit the files by hand.
> 
> R32/F32 - float[256,256] - read directly into/out of the
> heightmap with
> a conversion to/from doubles (we store all intermediary
> values as
> doubles internally, but save to/from files and DBs in
> single precision)
> 
> BMP, PNG, GIF, WMF - saves to/from 256 colour grayscale
> image, uses IIRC
> a scale from 1-128m so each shade is 0.5m (may be 1-511, I
> forget. Test.
> Only really for exporting, importing is going to be lossy)
> 
> JPEG - exports a false-colour coloured heightmap similar to
> the above.
> Same as the world map image.
> 
> TER - Load-only, Terragen - 16bit precision.
> 
>  
> 
> I personally recommend R32/F32 as most if not all terrain
> editing
> software can understand it. 
> 
>  
> 
> Re: USGS DEM (Important distinction as there are several
> varieties of
> DEM, including JDEM, EUDEM, etc) - I have been working on a
> supplemental
> terrain library for OpenSim which has support for USGS DEM
> files (and a
> variety of other more esoteric formats), however it is
> highly highly
> untested - use at own risk. Contact me if you want a beta
> copy.
> 
>  
> 
> Regards,
> 
>  
> 
> Adam
> 
>  
> 
> From: opensim-dev-bounces at lists.berlios.de
> [mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of
> Diva Canto
> Sent: Friday, 23 May 2008 10:28 PM
> To: opensim-dev at lists.berlios.de
> Subject: [Opensim-dev] DEM -> Raw
> 
>  
> 
> Hi,
> 
> I have a couple of questions about terrains. Where can I
> get more
> information about these raw formats that OpenSim
> understands? I tried
> Googling, but couldn't really figure it out. Are these
> 32-bit floating
> points, one per what?
> 
> Has anyone tried to produce RAW format files from DEM
> files?
> (http://en.wikipedia.org/wiki/USGS_DEM)
> 
> Any info appreciated!
> 
> Thanks,
> 
> Diva /
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