[FWTools] Van der Grinted apparent projection error

Frank Warmerdam warmerdam at pobox.com
Tue Jul 8 11:09:21 EDT 2008

Conor O'Donoghue wrote:
> Hello,
> I type gdalwarp -t_srs "+proj=vandg" 15deg02grid.tif 15deg02vandggrid.tif
> The input file is a whole world TIFF  (15degree raster grid, 5400 x 2700 
> pixels) and no compression.
> The output TIFF has two errors.
> 1) The image (map) that goes beyond 180 degrees to fill the corners of 
> this Van der Grinten tiff is incorrect in latitude, as evidenced by the 
> abrupt change of the angle of the latitude lines.
> 2) A band of longitude (approx 175 degrees to 180 degrees west arc) is 
> solid black where there should be projected image.
> I would be happy to supply the image that is self explanatory but not 
> sure if images are allowed.
> Con anyone help lead me to the solution?


I would encourage you to file a ticket with the GDAL project with this issue,
and attach the image describing the problem to that ticket.


(Note: you will need to create an OSGeo userid to file a ticket f you don't
already have one - instructions at above link)

There are a variety of challenges to doing world wide image reprojection so
it may be that you are running into known issues, and I can provide advice
on how to minimize the effect.  Or it may be something more specific that
needs to be fixed.

Best regards,
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    | President OSGeo, http://osgeo.org

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