[mapserver-users] Basic Projection Help

Matthew Pettis matthew.pettis at gmail.com
Sat Jun 28 01:47:49 EDT 2008


Hello,

I'm trying to get a handle on projections and reprojections.  I have a
dataset in a postgis database table that is in epsg:26915 (it's the state of
MN).  I know this from the metadata provided by the provider (state of
Minnesota itself).

When I loaded it into postgis, the geometry_columns row for this
table/column combo set srid=-1.  As I know that this is in epsg:26915, I
manually changed the geometry_columns row entry to it (see: ===
geometry_columns === section).

Problem is, I get an error of using two different geometries.  Anybody have
any idea how i set the srid to the correct value of epsg:26915?  I'd like to
set this correctly so I can reproject it as necessary.  The map will render
with srid=-1, but then I don't think I can reproject the image correctly,
right?

below are what I think are the important sections to this problem.  Thanks
in advance for your help.

Matt

=== url ===
======================================================================
http://localhost/cgi-bin/mapserv.exe?map=C:\ms4w\Apache\htdocs\ol\mapreproj.map&mode=map
======================================================================

=== error message ===
======================================================================
msDrawMap(): Image handling error. Failed to draw layer named 'state'.
msPOSTGISLayerWhichShapes(): Query error. Error executing POSTGIS SQL
statement (in FETCH ALL): DECLARE mycursor BINARY CURSOR FOR SELECT
asbinary(force_collection(force_2d(the_geom)),'NDR'),gid::text from
shp_state WHERE the_geom && setSRID('BOX3D(141095.125 4809728.25,810342.625
5478975.75)'::BOX3D, find_srid('','shp_state','the_geom') ) -ERROR:
Operation on two geometries with different SRIDs
======================================================================

=== geometry_columns ===
======================================================================
oid;f_table_catalog;f_table_schema;f_table_name;f_geometry_column;coor_dimension;srid;type
336791;"''";"public";"shp_state";"the_geom";2;26915;"MULTIPOLYGON"
======================================================================

=== mapreproj.map ===
======================================================================
MAP

    ################
    # Map attributes
    ################
  IMAGETYPE   PNG
  EXTENT      184056.505 4809728.25 767381.245 5478975.75
  SIZE        600 600
  IMAGECOLOR  255 255 255
  FONTSET     "C:/ms4w/Apache/htdocs/fonts/fonts.list"

    ####################
    # Web settings
    ####################
  WEB
    IMAGEPATH   "C:/ms4w/Apache/htdocs/tmp/"
    IMAGEURL    "/tmp/"
  END

    ####################
    # State
    # Background shows through missing precincts to show where no votes will
be coming from
    ####################
  LAYER
    NAME              "state"

    CONNECTIONTYPE    postgis
    CONNECTION        "user=postgres dbname=gisvote password=postgres"
    DATA              "the_geom from shp_state"
    STATUS            default
    TYPE              polygon

    CLASS
      NAME            "state"
      COLOR           200 200 200
    END

  END # Layer state

END
======================================================================


-- 
It is from the wellspring of our despair and the places that we are broken
that we come to repair the world.
-- Murray Waas
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