[mapserver-users] MapServer 4.8.3: MapScript setProjection

Rob gis at vanbooth.com
Tue Mar 11 07:10:11 EDT 2008


Hi

I'm supporting an instance of MapServer 4.8.3 and I am trying to improve the
performance of the map drawing.

I've a java app that modifies the JNI setProjection object, using
'init=epsg:27700' as its argument.

This seems to take approx 200ms for every layer that I add to my request
(rendered or not), which can drastically increase the time taken to draw a
map (my standard request includes 18 layers).

I read http://mapserver.gis.umn.edu/docs/howto/mapfiletuning about using
inline projection parameters and how it is much quicker than using an epsg
lookup, but I'm having problems.

Using http://spatialreference.org/ref/epsg/27700/ I determined that the
projection parameter should now be

'+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000
+ellps=airy +datum=OSB36 +units=m +no_defs'

but this just gives me an error in setProjection - unknown eliptical
parameter name.

The advice here (
http://comments.gmane.org/gmane.comp.gis.mapserver.user/18519) suggests that
I should be using the proj4 format - is that correct?

Does anybody have any idea how I can modify my projection parameter so that
it works?  FWIW, upgrading MapServer is probably out of the question.

MTIA

Rob
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