Hi Robert, A bit off topic, but as far as preprocessing the data goes, I've found that building overviews using gdaladdo allows osgdem to run MUCH faster than if there are no overviews present, so it does more than just help with aliasing artifacts as you mention. By having the overviews built, the initial lower LOD levels build much quicker due to the fact that GDAL can take advantage of the pre-built overviews.
Another nice way to increase speed in database generation is to make sure that the images and terrain you use return tiles for their blocksize rather than scanlines. An easy way to do this is during the call to gdal_translate, create a geotiff using the "-of GTiff" option and use creation options "-co TILED=YES". As osgTerrain deals with tiled blocks in the quad tree, this makes more efficient use of GDAL's block cache than if the data returns an entire scan line for a block. Thanks! Jason -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert Osfield Sent: Friday, December 15, 2006 4:24 A To: osg users Subject: Re: [osg-users] Building Blue marble images Hi Looch, You shouldn't need to preprocess the data at all, save for creating the overlays using GDAL to help reduce aliasing artifcats associated with GDAL downsamping the data on the final database build. This step isn't critical though, its just a image quality step. I'd recommend just going for the main database pager generation run to make sure things are working sweetly first. You line: osgdem --PagedLOD --bluemarble-west -t west.tif --bluemarble-east -t east.tif --whole-globe -d topo.tif --geocentric -v 1.0 -l 12 -o earth.ive Could be simplified a little as --PagedLOD is the default, and -v 1.0 is the default so: osgdem --bluemarble-west -t west.tif --bluemarble-east -t east.tif --whole-globe -d topo.tif --geocentric -l 12 -o earth.ive Should work fine. As the parameters to osgdem can be a bit long winded I typically place the osgdem call into a shell script and simply run this when I need to rebuild. This way if I make a mistake in the options I can simple stop the build, edit the option, and rerun. Robert. _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/ _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
