[gdal-dev] using gdalwarp with a new projection in proj.4

[Markus Müller]

Hi Frank,

thanks for the reply. I did as you suggested and gdalsrsinfo acts accordingly.


>>>
gdalsrsinfo '+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext'


PROJ.4 : '+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext'


OGC WKT :
PROJCS["unnamed",
    GEOGCS["WGS 84",
        DATUM["unknown",
            SPHEROID["WGS84",6378137,298.257223563]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],
    PROJECTION["custom_proj4"],
    EXTENSION["PROJ4","+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext"]]

>>>


I then tried the same with gdalwarp (on one of the examples file that comes with GDAL)


>>>
 gdalwarp -s_srs EPSG:26711 -t_srs '+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext' ~/data/utm_orig.tif rhealpix.tif
Processing input file /home/markus.mueller/data/utm_orig.tif.
ERROR 6: Failed to initialize PROJ.4 with `+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext'.
0...10...20...30...40...50...60...70...80...90...100 - done.

>>>


It produces an output file though. Should I be concerned about the created error or can I ignore it?




Many thanks,


Markus

---- On Tue, 16 Jul 2013 23:55:05 -0700 Frank Warmerdam <warmerdam at pobox.com> wrote ---- 


Michael,


Healpix is not directly supported by OGRSpatialReference - the core of the coordinate system machinery for GDAL/OGR.  However, you can request GDAL to treat this as a PROJ.4 extension to WKT by adding the +wktext flag.  I would add that the -E and -f flags are options to the cs2cs commandline program, and not part of a PROJ.4 coordinate system and so should not be included.  The result is something like this:
 
gdalsrsinfo '+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext'

PROJ.4 : '+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext'

OGC WKT :
PROJCS["unnamed",
     GEOGCS["WGS 84",
        DATUM["unknown",
            SPHEROID["WGS84",6378137,298.257223563]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],
     PROJECTION["custom_proj4"],
    EXTENSION["PROJ4","+proj=rhealpix -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 +wktext"]]


Best regards,
Frank


 

On Tue, Jul 16, 2013 at 6:48 PM, Michael Speth <spethm at landcareresearch.co.nz> wrote:
  Greetings,   I am unable to use the HEALpix and rHEALPix projections which have been added about a year ago to proj.4 in gdalwarp.  Is there a configuration file for gdal that needs to be updated for this projection?
 
 
 Here is the command in question that fails:
  gdalwarp -s_srs EPSG:26711 -t_srs '+proj=rhealpix -f '%.2f' -I +lon_0=0 +a=1 +ellps=WGS84 +npole=0 +spole=0 -E'  ~/data/utm_orig.tif rhealpix.tif
 The error message
 “Translating source or target SRS failed:”
 
 
 
 Thanks
 -- 
 Michael Speth Research Systems Developer Landcare Research 
 
 
  
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-- 
---------------------------------------+--------------------------------------
 I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
 and watch the world go round - Rush    | Geospatial Software Developer
 
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