[Proj] Bad Mercator Projection string?

Geoff Shipton geoff at tritonimaginginc.com
Thu Jul 19 15:51:12 EST 2012



Many thanks you could be right, I had noticed that the lat_ts parameter was
not present in any of the other "typical" Mercator Proj4 strings I came
across - I will give this a try and let you know.




From: Mikael Rittri [mailto:Mikael.Rittri at carmenta.com] 
Sent: Thursday, July 19, 2012 10:41 AM
To: <geoff at tritonimaginginc.com>; PROJ.4 and general ProjectionsDiscussions
Cc: proj at lists.maptools.org; Howard Unkeles
Subject: Re: [Proj] Bad Mercator Projection string?


I don't know what the trouble is, but maybe GeoTIFF doesn't support Mercator

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>:

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

The information contained in this message may be privileged or confidential
information intended solely for the use of the addressee(s).  Any views or
opinions presented in this communication do not necessarily represent those
of Triton Imaging, Inc.  If the reader of this message is not the intended
recipient, you are hereby notified that any dissemination, distribution or
copying of this communication is strictly prohibited.  If you have received
this communication in error, please immediately notify me and you are hereby
instructed to delete all electronic copies and destroy all printed copies.


Proj mailing list
Proj at lists.maptools.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.maptools.org/pipermail/proj/attachments/20120719/d96c89f0/attachment.htm 

More information about the Proj mailing list