[Mapserver-users] SDE queries and projection

[Steve Lime]

You only have to define a LAYER projection object if it differs from the
overall MAP projection object. So, if the layer and the output map are
in lambert then there's no need to define any projections. For SDE, as
will all data sources projections are handled by MapServer using Proj.4
for consitancy. Queries of projected data work like this:

  - image xy coordinates are converted to the display projection
(defined in MAP block)
  - the resulting coordinates are then converted to the LAYER
projection, if necessary
  - search proceeds as normal

Depending on how the rest of your mapfile is setup this could certainly
be the root of your problems.

Steve

Stephen Lime
Data & Applications Manager

Minnesota DNR
500 Lafayette Road
St. Paul, MN 55155
651-297-2937

>>> "Debbie Pagurek" <pagurekd at agr.gc.ca> 12/13/02 09:32AM >>>
Hi everyone, 
I have determined that the problem I've been having with getting
mapserver to query (nquery) an SDE layer is related to projection.

The SDE layer is in Lambert Conformal Conic.
I am defining this in the mapfile "LAYER" as:
PROJECTION
  "proj=lcc"
  "ellps=GRS80"
  "lat_0=0"
  "lon_0=-91.866667"
  "lat_1=49"
  "lat_2=77"
END

I only have this one layer in my application.  Do I have to set the WEB
projection object as the same?  My extents and units are set up
correctly in meters.

A click on the map for an nquery is returning
msSDELayerGetShape(): SDE error. SE_stream_fetch(): Shape or row not
found. (-22) 

and I suspect that the pixel coordinates are not being transformed
properly to map coordinates.

FOr those of you who have SDE queries working, what projection setup
are you using?  i.e. what projection is the sde layer stored in and how
are you setting up your mapfiles?  Any copies of mapfiles would be much
appreciated!

Thanks,
D. Pagurek



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