[Projection problem] - simple translation

[Gail]

Selim,

There are 4 places where projection information is specified in a mapfile. 

1) The first is in the WEB object e.g. "wms_srs" "EPSG:27700" This gives the
projection the data is originally in, in this case you would specify 2 epsg
codes if you have data in two different projections. In my case the data is
originally in EPSG:27700

2) The PROJECTION object e.g. PROJECTION "init=epsg:4326" This tells
MapServer which projection the data should be viewed in therefore if the
data is not originally in this projection it will be projected on the fly to
the projection specified here. So in my case the data is reprojected to espg
4326

3) In the LAYER object there is a PROJECTION object within the LAYER object.
This should be specified the same as that within the PROJECTION object
towards the top of the mapfile, in my case this is EPSG 4326 (2). Finally in
the METADATA object which is also within the LAYER object the "wms_srs"
should be what the original data layer projection is so in my case this is
EPSG: 27700 (same as in the web object).

I hope you find this helpful and get the two layers showing up together.

Gail

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Gail Rebecca Millin
Geodata Interoperability Support Officer
-------------------------------------------------------------
MIMAS
Manchester Computing
The University of Manchester
Oxford Road
Manchester
M13 9PL
 
Telephone: +44 (0) 161 275 0581
E-mail: Gail.Millin at manchester.ac.uk
Website: http://www.mimas.ac.uk/spatial
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-----Original Message-----
From: Selim Hernandez [mailto:pimpoumvlan at HOTMAIL.COM] 
Sent: Tuesday, August 02, 2005 9:56 AM
Subject: [Projection problem] - simple translation

Hello,

I think my problem is simple but since I don't understand how the
projection system work, it seems confusing to me.

I have a map file with 2 layers that have 2 types of coordinates.
In fact, the two types are nearly the same, but on one of them, 3000000 has
been addded to the Y coordinate.

For example : (from a mif file)
here are the 2 types of coordinates (with or without 3000000) for the same
2 points.

REGION 1                   REGION 1
6                          6
887807.365 3091440.265     887807.365 91440.265
887818.530 3091439.880     887818.530 91439.880
...                        ....

I don't succeed in displaying both at the same time. I think I have to add
a PROJECTION object in my layers on maybe in my map object but I don't
understand the way it works.

If anyone has any idea, it would be very helpful.

thank you