[Proj] Bad Mercator Projection string?

Mikael Rittri Mikael.Rittri at carmenta.com
Thu Jul 19 12:40:51 EST 2012

I don't know what the trouble is, but maybe GeoTIFF doesn't support Mercator with
a lat_ts parameter (latitude of true scale). If so, you can try to use a scale factor instead.

That is, replace your




This will give you an equivalent definition, and maybe it will work better.

Best regards,

Mikael Rittri

18 jul 2012 kl. 19:16 skrev "Geoff Shipton" <geoff at tritonimaginginc.com<mailto:geoff at tritonimaginginc.com>>:

Hello everyone,

We “inherited” this Proj4 string from a previous product – it has always seemed to work but we are having problems using it with gdalwarp, the warped .tif image looks valid but has errors in the TIF tags.  If anybody has any idea what’s wrong I would be grateful.  Comparing it with other Mercator Proj4 strings it looks a bit simple…

Here’s the string:

+proj=merc +datum=WGS84 +lon_0=0 +lat_ts=41.5 +x_0=0 +y_0=2000000

I am not a geodesist, be gentle.

Many thanks,
Geoff Shipton,
Triton Imaging Inc.
Customer Support.
Capitola CA.
geoff at tritonimaginginc.com<mailto:geoff at tritonimaginginc.com>

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