[osg-users] [vpb] How to? - gdal_translate .asc to geoTiff and osgdem to flat terrain

tim paige tim.paige at cox.net
Wed Apr 6 17:05:42 PDT 2011


Hi,

My starting file of interest is an ASC file with the following gdalinfo

Driver: AAIGrid/Arc/Info ASCII Grid
Files: sd_1_3_110805.asc
Size is 11880, 9720
Coordinate System is `'
Origin = (-117.900000000000010,33.399999999999991)
Pixel Size = (0.000092592592593,-0.000092592592593)
Corner Coordinates:
Upper Left  (-117.9000000,  33.4000000) 
Lower Left  (-117.9000000,  32.5000000) 
Upper Right (-116.8000000,  33.4000000) 
Lower Right (-116.8000000,  32.5000000) 
Center      (-117.3500000,  32.9500000) 
Band 1 Block=11880x1 Type=Float32, ColorInterp=Undefined
  NoData Value=-9999
 
Then I would translate to a tiff

Code:
gdal_translate sd_1_3_110805.asc lj.tif



Then I used osgdem

Code:
osgdemd --cs "+proj=latlong +datum=WGS84" -d sd_1_3_110805.asc -l 6 -v 2 -o lj.ive 



I would like to translate that file to one suitable for creating a flat terrain for use with osgOcean. Doing anything less than specifying geocentric yields a nice terrain database that is 180 degrees out, so I give up on that.

My desire is to take my interesting combination of bathymetric and topographic elevation data (which I can view geocentrically correctly) and make a flat terrain which will still allow me to get lat lon and alt usage. I would like to be able to "fly" above and below my section of ocean which I hope to place in the area of interest while moving around. 

In this "ocean centric" world, I have had problems finding my terrain with reference to my ocean and model. 

Ongoing questions...
1. what may I use for gdal_translate to get in shape for flat terrain?
2. could I do it all with osgdem?
3. why is my conversion "backwards" unless I specify geocentric?
4. If I use a geocentric model... what would be appropriate to use in order to get my landmass in a position suitable for my fixed ocean?
5. Does a getBoundingSpere on a geocentric terrain model return the center of the earth? Or does it return the center of the peaks and valleys of the model? (either way I have been unsuccessful in moving mountains such that they are visible with my ocean)

I am using "bathymetryDEM" located at...
 http://seafloor.csumb.edu/SFMLwebDATA_s.htm#LJ 
Thank you!

Many cheers,
tim[/code]

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http://forum.openscenegraph.org/viewtopic.php?p=38274#38274








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