RE: [osg-users] osgdem decend

Lynn,
I made this spreadsheet to help me figure out how many LODs are required to
produce the desired resolution output. I think I have correctly captured the
calculations in osgTerrain. Maybe Robert can verify.

You don't specify the extents of your output in the command line, so I
assume that you are producing a full globe. (You also don't use the
--geocentric option, so your output will be flat.)

According to my calculations, you'd need 17 LODs to see the full resolution
of the 1m (=0.033333 arcsec) imagery at 256 samples per tile. At 8 LODs you
are only seeing 19.77 arcsec/sample, or 593 meter/texel resolution textures.

HTH,
Thom

--
Thom DeCarlo
---------------------------------------------------------
 A polar bear is a rectangular bear after a coordinate transform.
> -----Original Message-----
> From: Lynn Thompson
> Sent: Monday, January 10, 2005 4:58 PM
> To: osg-users@openscenegraph.net
> Subject: [osg-users] osgdem decend
> 
> I have downloaded 1"NED elevation and LandSat7 data from
> seamless.usgs.gov.  When generating terrain via osgdem with this source
> data the cumulative size of the resulting tiles is less than that of the
> source data.  The output looks good and I am using the --compressed
> option, so that may account for the difference.
> 
> When I add 1.0m Ortho imagery to the mix, the Ortho imagery gets
> utilized but is grainy and not near the quality of the source imagery.
> My osgdem command is as follows.  This procedure completes at LOD 6 even
> though I've specified Level 8.  I've tried varying values for
> --tile-terrain-size, --tile-image-size,
> --radius-to-max-visible-distance-ratio, and --skirt-ratio.
> 
> Any help would be greatly appreciated.
> 
> Thanks.
> 
> Lynn Thompson
> 
> osgdem -t ../texture -d ../elevation -l 8 -PagedLOD --RGB-24
> --compressed
> --mip-mapping-hardware --max-anisotropy 1.0 --tile-image-size 256
> --tile-terrain-size 64 --cs "+proj=latlong +datum=WGS84"
> --radius-to-max-visible-distance-ratio 7.0 --skirt-ratio 0.002 -o
> MyTiles.ive
> 

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