[gdal-dev] Geostationary Projection with microradians

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

[gdal-dev] Geostationary Projection with microradians

Zachary Flamig
Hi all,

The GOES-16 satellite has started delivering full disk netcdf files that conform to a new portion of the CF standard: https://cf-trac.llnl.gov/trac/ticket/72
Unfortunately, they choose to use units of micro-radians instead of meters so it doesn’t appear the files are immediately compatible with GDAL.

It is rather straight forward to convert from the radians to meters given the height of the satellite (which is included in the projection information). Would this be something appropriate for GDAL to convert or is it more of a PROJ4 problem?

I’ve uploaded some example netcdfs here: https://www.dropbox.com/s/ell4iy0hiwzquqy/fulldisk_wv.zip?dl=0
The data is tiled into 4 separate netcdfs that can be combine for the full disk image.

Cheers,
Zac

_______________________________________________
gdal-dev mailing list
[hidden email]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Geostationary Projection with microradians

Even Rouault-2

On mercredi 8 mars 2017 14:55:36 CET Zachary Flamig wrote:

> Hi all,

>

> The GOES-16 satellite has started delivering full disk netcdf files that

> conform to a new portion of the CF standard:

> https://cf-trac.llnl.gov/trac/ticket/72

> <https://cf-trac.llnl.gov/trac/ticket/72> Unfortunately, they choose to use

> units of micro-radians instead of meters so it doesn’t appear the files are

> immediately compatible with GDAL.

>

> It is rather straight forward to convert from the radians to meters given

> the height of the satellite (which is included in the projection

> information). Would this be something appropriate for GDAL to convert or is

> it more of a PROJ4 problem?

 

I don't pretend to have a very well informed opinion on the GEOS projection, but if you can fix that in GDAL and do the conversion from microradians to meters it seems reasonable. Projection support in WKT and proj.4 assumes that the units of x, y values are linear (meter, feet, etc...), so dealing with angular units would probably be complicated at that level. Especially since the conversion from microradians to meters depend on another parameter (height of the satellite). So a fix in the netCDF driver would seem OK to me.

 

>

> I’ve uploaded some example netcdfs here:

> https://www.dropbox.com/s/ell4iy0hiwzquqy/fulldisk_wv.zip?dl=0

> <https://www.dropbox.com/s/ell4iy0hiwzquqy/fulldisk_wv.zip?dl=0> The data

> is tiled into 4 separate netcdfs that can be combine for the full disk

> image.

>

> Cheers,

> Zac

 

 

--

Spatialys - Geospatial professional services

http://www.spatialys.com


_______________________________________________
gdal-dev mailing list
[hidden email]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
Loading...