Re: [OSSIM] OSSIM Elevation

[David B. <db...@gm...>]

Hi Mike,

elevation_manager.elevation_source0.type: srtm_directory

Would look for dot.hgt files(raw raster). If you want to use tiffs change
it to "image_directory". Also don't forget to setup the geoid in your
preferences.
geoid_egm_96_grid:  /usr/local/ossim/share/ossim/geoids/egm96.grd

$ ossim-info --height 39.5 -105.5
elevation.info.cell:  /data1/elevation/srtm/1arc/N39W106.hgt
elevation.info.geoid_name:  geoid1996
elevation.info.geoid_offset:  -13.8020000457764
elevation.info.gpt:  (39.5,-105.5,0,WGE)
elevation.info.height_above_ellipsoid:  2769.19799995422
elevation.info.height_above_msl:  2783

Hope that helps.

Take care,
Dave


On Tue, Dec 6, 2022 at 6:04 PM Mike Thompson <mik...@gm...> wrote:

> I recently built and installed OSSIM but am having trouble using elevation
> data.
> OS: Ubuntu 22.04.1 LTS
> ossim-info --version
> 1.9.0
>
> Snip from my ossim_preferences.txt file:
> elevation_manager.elevation_source0.connection_string:
> $(OSSIM_DATA)/elevation/srtm/1arc_tif_from_USGS
> //elevation_manager.elevation_source0.connection_string:
> /home/mike/elevation/srtm/1arc_dt2_from_USGS
> //elevation_manager.elevation_source0.connection_string:
> /home/mike/elevation/srtm/1arc_ras_from_tif
> //elevation_manager.elevation_source0.connection_string:
> /home/mike/elevation/srtm/1arc_bil_from_USGS
> //elevation_manager.elevation_source0.filename:
> /home/mike/elevation/srtm/1arc_bil_from_USGS
> elevation_manager.elevation_source0.enabled: true
> elevation_manager.elevation_source0.type: srtm_directory
> elevation_manager.elevation_source0.min_open_cells: 25
> elevation_manager.elevation_source0.max_open_cells: 50
> elevation_manager.elevation_source0.memory_map_cells: false
> elevation_manager.elevation_source0.geoid.type: geoid1996
>
> (the lines which are commented out are other things I have tried)
>
> I downloaded 1 arc second SRTM data from USGS, I tried all available
> formats: .bil, .tif, and .dt2.  I also tried converting the .tif to a .ras.
> Specifically, I downloaded n39_w106_1arc_v2.*
>
> ossim-info --check-config reports:
> elevation sources loaded:
> elevation_source[0].connetion_string:
> /home/mike/elevation/srtm/1arc_tif_from_USGS
>
> This is encouraging, but
> $ ossim-info --height 39.5 -105.5
> reports:
> elevation.info.cell:  not_found
>
> I loaded the data from USGS into QGIS to confirm my assumption that 39.5
> -105.5 is within the specified file.
>
> I have also tried renaming the SRTM files from the USGS to:
> n39w106.*
> which I understand is the convention for SRTM.
>
> Any help would be appreciated.
>
> Thanks,
>
> Mike
>
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