[gdal-dev] Question on gdal_contour and limiting the range of contours generated.

[Stephen Woodbridge]

Jukka,

Thanks! After trying shapefile and exceeding 2GB, I switched to postgres 
and deleted the elevation as you suggested.

I'm working with a global relief model the includes both elevation and 
bathymetry depth over the whole world at about 15 arc-sec/pixel. I 
generates a lot of contour lines between 8,000 and -10,000 meters, I was 
think it would be handy to gdal_dem had a few more options to control 
the range and direction of contour generation.

I also have played with gdal_calc to create an elevation and bathymetry 
only files.

Thanks, I think I have workarounds for the moment.

-Steve W

On 10/31/2019 4:38 AM, jratike80 wrote:
> Second thought, perhaps I would just delete unnecessary contour lines
> afterwards instead of flattening the DEM.
>
> gdal_contour -f gpkg -a elev -off -121.92 -i 1.524
> bathy-value/crm_vol2.nc.tif bathy-contours/crm_vol2.nc-5.gpkg
>
> ogrinfo -sql "delete from crm_vol2.nc-5 where elev>0"
> bathy-contours/crm_vol2.nc-5.gpkg
>
> ogrinfo -sql "VACUUM" bathy-contours/crm_vol2.nc-5.gpkg
>
> -Jukka-
>
>
>
> jratike80 wrote
>> Hi,
>>
>> I believe I would use gdal_calc https://gdal.org/programs/gdal_calc.html
>> and
>> make the terrain above the sea level flat before creating the contours.
>> And
>> I would avoid shapefiles and use GeoPackage as output format.
>>
>> There is a button "Edit on GitHub" in the top-right corner on page
>> https://gdal.org/programs/gdal_contour.html, feel free to test it.
>>
>> -Jukka Rahkonen-
>
>
>
>
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