What I mean is that you can define almost any projection you like in
Geoserver, as long as the "math" (tranformation) is available via geotools.
For example, I needed an Albers projection for the USA lower 48 states which
was not already defined in geoserver. I was able to define this new
projection because geosever already has the math for Albers....I just needed
to provide new parameters such as the latitude and longitude of origin, the
standard parallels, etc....then I entered this new projection in both my
postGIS database and then in the epsg db in geoserver. Now geoserver can
"understand" coordinates in this projection, reproject data into and out of
this projection, etc.
For the Lambert Azimuthal Equal Area projection we would both like to use,
the math/tranformation is not yet available in geoserver, so I can't use or
define any variation of the Lambert Azimuthal Equal Area projection.
Hope that helps,
Steve
-----Original Message-----
From: Amy Johnson [mailto:ajohnson@anonymised.com]
Sent: Friday, August 10, 2007 12:51 PM
To: Stephen Crawford
Cc: 'geoserver users'
Subject: Re: [Geoserver-users] Projection question
Thanks very much. Can you help me understand part of what you said? I'm not
sure what you mean by defining my own projection based on a transformation.
I thought what Geotools is providing is a transformation between
projections. Is that not correct?
Stephen Crawford wrote:
The Lambert Azimuthal Equal Area projection is not available for GS
1.4.x or 1.5.x....I know beacause I REALLY NEED to use it also. This
is because the transformation is not available for geotools 2.3.x,
which GS 1.4 and 1.5 is based on. From what I understand, GS 1.6 will
be based on geotools 2.4, which does have the projection in question.
Geoserver CAN support any projection for which it's version of
geotools has the tranformations....though you may have to define your
own projection based on the transformation.
Transformatons for geotools 2.3 can be found here:
http://svn.geotools.org/geotools/branches/2.3.x/module/referencing/src
/org/g eotools/referencing/operation/projection/
And geotools 2.4 (in upcoming 1.6):
http://svn.geotools.org/geotools/branches/2.4.x/modules/library/refere
ncing/ src/main/java/org/geotools/referencing/operation/projection/
Good luck,
Steve
Stephen Crawford
Center for Environmental Informatics
The Pennsylvania State University
-----Original Message-----
From: geoserver-users-bounces@lists.sourceforge.net
[mailto:geoserver-users-bounces@lists.sourceforge.net] On Behalf Of
Amy Johnson
Sent: Thursday, August 09, 2007 3:59 PM
To: geoserver users
Subject: [Geoserver-users] Projection question
I am trying to understand how to choose an EPSG for a map. I am using
Geoserver 1.4.0-RC5 and having trouble with a Lambert Azimuthal Equal
Area projection. The data for it is as follows:
Longitude_of_Projection_Center: -100.00
Latitude_of_Projection_Center: 45.00
False_Easting (metres): 0.0
False_Northing (metres): 0.0
Semi-major_Axis: 6370997.0
Denominator_of_Flattening_Ratio: 1.0
Ellipsoid_Name: Sphere
Units: metres
I can find nothing similar in Geoserver. Also, does Geoserver
necessarily support what Geotools does for EPSG values?
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