Hello all,
I have a quick question regarding the datum assumption when entering
lon/lat data into a Basemap object.
My understanding is that Basemap will use the datum specified upon
creation, the default being a sphere of radius 6,370,997 meters and
assume that the lon, lat entered in a call follows the same
convention. Then, if you have lon lat which uses a different datum
to the projection of the basemap you must convert this to lon/lat in
the correct datum before then converting to projection coordinates
using the basemap object. Is that correct?
Assuming my understanding above is correct, I don't feel that this
process is made clear in the documentation for basemap and I’m sure
many make the mistake of thinking of lon/lat as an absolute across
all geodetic standards. I know ignorance is not an excuse, but it
might be nice if people got a more explicit warning to take care
with their inputs.
For reference, I found this blog which describes the datum mistake
nicely:
Kindest regards,
Mat
···
http://ragrawal.wordpress.com/2009/01/24/a-point-about-latitudelongitude
–
Dr. Mathew Topper
Institute for Energy Systems
School of Engineering
The University of Edinburgh
Faraday Building
The King’s Buildings
Edinburgh EH9 3JL
Tel: +44 (0)131 650 5570
School fax: +44 (0)131 650 6554
mathew.topper@...3926...
[http://www.see.ed.ac.uk](http://www.see.ed.ac.uk/)