[Proj] Fwd: [gdal-dev] gdalwarp EPSG:32662 problem

[Antti Castrén]

Hello Steve,

You asked for any thoughts, so here are some.

The 20km shift could easily be caused by using spherical version in
one implementation of equirectangular projection and ellipsoidal
version in the other. Amount of shift depends on the latitude.

You can find some information on these pages:

http://www.remotesensing.org/geotiff/proj_list/equirectangular.html

http://comments.gmane.org/gmane.comp.gis.proj-4.devel/981

Read especially the comments of the latter.

Hope these help,

  Antti

2014-02-08 8:11 GMT+02:00 Stephen Woodbridge <woodbri at swoodbridge.com>:
> Hi,
>
> Sorry for cross posting. This seems like a proj4 issue but might be gdal
> related.
>
> I've run into a problem that I think is related to a change in the EPSG
> definition for EPSG:32662
>
> The symptom is that the image after gdalwarp reprojection is about 20km
> south of where it should be.
>
> old system is correctly aligned:
>
> GDAL 1.4.2.0, released 2007/06/27
> proj Rel. 4.5.0, 22 Oct 2006
>
> # WGS 84 / Plate Carree
> <32662> +proj=eqc +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84
> +units=m +no_defs  <>
>
> new system is shifted about 20km south:
>
> GDAL 1.9.2, released 2012/10/08
> proj Rel. 4.8.0, 6 March 2012
>
> # WGS 84 / Plate Carree (deprecated)
> <32662> +proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84
> +units=m +no_defs  <>
>
>
> http://spatialreference.org/ref/epsg/32662/
> This indicates that the definition in proj 4.8.0 is wrong. Would the
> +ellps=WGS84 account for this shift?
>
> Any thoughts on this?
>
> Thanks,
>   -Steve