[Mapserver-users] Serving PostGIS Projected Data

Mon Jun 16 14:57:42 PDT 2003

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Hi list,

With my limited use of PostGIS and MapServer I've only ever played
around with data in geographic coordinates which is loaded into PostGIS
with an SRID of -1. I now need to load up some data that is in a custom
Mercator projection (changed the central meridian to 150 instead of 0).
The SRID number of our custom projection in the spatial_ref_sys table is
999001 which is based on the record with an SRID of 54004. The proj4text
for 999001 looks like "+proj=merc +lat_ts=0 +lon_0=150 +k=1.000000
+x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 units=m". When I load up the
data, each record has an SRID of 999001.

Is this all I need to do on the PostGIS side of things?

I've now added the layer to a bare mapfile but the data is showing up
like it would with a -1 srid. I have no projection information of any
sort defined in the mapfile so I assume I need to define a PROJECTION
section in the mapfile. Correct?

How do I do this for a custom projection? I've found examples on the
list like the following which show how to enter the projection section
in a mapfile, but I can't figure out what I should put in here.

PROJECTION
  "proj=lcc"
  "ellps=GRS80"
  "lat_0=49"
  "lon_0=-95"
  "lat_1=49"
  "lat_2=77"
END

Thanks,

Benjamin Wragg

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<div class=3DSection1>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hi list,</span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>With my limited use of PostGIS and MapServer =
I’ve only
ever played around with data in geographic coordinates which is loaded =
into
PostGIS with an SRID of -1. I now need to load up some data that is in a =
custom
Mercator projection (changed the central meridian to 150 instead of 0). =
The
SRID number of our custom projection in the spatial_ref_sys table is =
999001
which is based on the record with an SRID of 54004. The proj4text for =
999001
looks like “+proj=3Dmerc +lat_ts=3D0 +lon_0=3D150 +k=3D1.000000 =
+x_0=3D0 +y_0=3D0
+ellps=3DWGS84 +datum=3DWGS84 units=3Dm”. When I load up the data, =
each record
has an SRID of 999001.</span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Is this all I need to do on the PostGIS side of =
things?</span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

I’ve now added the layer to a bare mapfile but =
the
data is showing up like it would with a -1 srid. I have no projection
information of any sort defined in the mapfile so I assume I need to =
define a
PROJECTION section in the mapfile. Correct?

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

How do I do this for a custom projection? I’ve =
found
examples on the list like the following which show how to enter the =
projection
section in a mapfile, but I can’t figure out what I should put in =
here.

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

<pre><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt'>PROJECTION</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"proj=3Dlcc"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"ellps=3DGRS80"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"lat_0=3D49"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"lon_0=3D-95"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"lat_1=3D49"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt'>  =
"lat_2=3D77"</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt'>END</span></font></pre><pre><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt'> </span></font></pre>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thanks,</span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Benjamin Wragg</span></font></p>

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