[Mapserver-users] Projection Questions - MapScript

[Lowther, David W]

although, im running a mapserver reprojecting ALL of my vector data (roads,
hydro, etc...) from LL to albers and it doesn't seem to care a bit. the data
are in shapefiles and range in size from 20 records to 900,000 for the
roads.

Dave

-----Original Message-----
From: Hankley, Chip [mailto:Chip.Hankley at GASAI.Com]
Sent: Monday, December 16, 2002 3:34 PM
To: 'bwragg at tpg.com.au'; mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] Projection Questions - MapScript


Yup... all that's possible. Note that 'buffer' is a bit of a loaded word, as
MapServer does not currently support buffers in the traditional GIS meaning
of the word. However, you can do queryByPoint (specifying a buffer) or
queryByShape (if you made a shape using other MapScript commands).

As far as the projection question, yes, you can change the projection of the
map.

As far as performance goes, it depends. If you set up your app so that you
are re-projecting a lot of detailed data on the fly (images, detailed vector
data sets, etc.) it will obviously result in a greater performance hit than
if you were reprojecting simple stuff.

Chip

-----Original Message-----
From: Benjamin Wragg [mailto:bwragg at tpg.com.au]
Sent: Monday, December 16, 2002 3:25 PM
To: mapserver-users at lists.gis.umn.edu
Subject: [Mapserver-users] Projection Questions - MapScript


I'm doing some investigation into the use of MapServer and I have a
query on the projection capabilities of MapServer. From what I've learnt
the following steps should be possible, but I just wanted to check them
with someone:

1. Pass an x y coorindate to the ms_newPointObj() constructor to create
a new point.
2. Change the projection of the point to the projection of the rest of
the map, using the project method.
3a. Use the newly projected point to select features in a layer that
intersect the point.
							Or
3b. Put a buffer around the point and then select features in a layer
that intersect the point.
 
Also is it possible to change the projection of a whole map by using the
setProjection method? 
What is the performance degradation of re projecting a whole map?

Thanks,

Benjamin Wragg


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