[mapguide-users] Access DB and coord systems

[Gord McKenzie]

I am using UTM Zone 12 North Meters.  As you can see from the details below,
the data does draw in the map but the objects are still at there LL
coordinates.  This is data that works just fine in a Mapguide 6.5 install
doing the same basic thing.  The data is in the right part of the world.

 

We had our local Autodesk dealer try to do something similar and they had
the same problem.

 

The Server is Enterprise 2007 and the Author software is Studio 2007.  Works
the same on open source server.

 

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From: Dave Wilson [mailto:dave.wilson at autodesk.com] 
Sent: Thursday, August 31, 2006 11:49 AM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Access DB and coord systems

 

I can't see anything obvious from the XML.

 

What UTM coordinate system are you using?

 

Does the LL83 data actaully map within the UTM coordinate system? I know
this is a dumb question, but it's possible to mistakenly try to display
Hawaii data from LL83/4 in a UTM for say Montana which will never work. If
the map was orginally created with the data in UTM it's extent was set to
that of the first layer imported. This may not be the full extent of the UTM
coordinate system. Are you sure that when you zoom out the data isn't in the
correct place within the UTM extent and it's just a zoom issue?

 

Dave

 

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From: Gord McKenzie [mailto:gord.mckenzie at canam.com] 
Sent: Thursday, August 31, 2006 8:10 AM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Access DB and coord systems

Here is the result of my getresourcedata query.  Does this help clarify
where the problem is occurring?

 

As this happens right in the Autodesk Studio tool, shipping version, I
wonder if anyone from Autodesk can tell me what they think might be going on
here.

 

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From: Traian Stanev [mailto:traian.stanev at autodesk.com] 
Sent: Wednesday, August 30, 2006 4:11 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Access DB and coord systems

 

 

Reprojection is done on a stream of data that is independent of the source
-- SDF, SHP, Oracle, etc. all pass through the same code for reprojection.
That's why it has to be a problem with the way that code gets the coordinate
system from the FDO provider (or the provider giving it the wrong coordinate
system). 

 

It makes sense that the data still displays because one of the possible
fallbacks in that code is to default to identity transform. So your LL data
will (incorrectly in this case) display at UTM coordinates close to the UTM
origin (between 0 and 180 meters).

 

-----Original Message----- 
From: Gord McKenzie [mailto:gord.mckenzie at canam.com] 
Sent: Wed 8/30/2006 5:33 PM 
To: users at mapguide.osgeo.org 
Cc: 
Subject: RE: [mapguide-users] Access DB and coord systems

Not sure if this means much but the data is actually drawn on the map.  If I
pan and zoom to the LL coordinates I find my data is there.  So my source
data is in LL and my map in UTM.  The weblayout preview shows me that I am
zoomed to the extents of my UTM window.  Never the less, the data from my
access table is still drawn at it's LL coordinates.  Going to try this with
a SQL Server table and see if that makes any difference.

 

I used the getresourcedata function to get an XML output of the Access data
source and it would seem to confirm that it knows about LL83 and only LL83.

 

Anyone actually successfully transforming LL cords from a DB to something
else and if so what database are you using?

 

Gord 

 


  _____  


From: Traian Stanev [mailto:traian.stanev at autodesk.com] 
Sent: Wednesday, August 30, 2006 1:40 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Access DB and coord systems

 

 

One thing I can think of would be if your ODBC connection lists more than
one coordinate system when queried by the server and the server then could
end up using the wrong one for repro, which would result in the behavior you
describe. Another possibility is that it didn't parse the WKT string
correctly for the ODBC connection, although that's unlikely, given that LL83
is a popular one.

 

Traian

 


  _____  


From: Gord McKenzie [mailto:gord.mckenzie at canam.com] 
Sent: Wednesday, August 30, 2006 3:34 PM
To: users at mapguide.osgeo.org
Subject: [mapguide-users] Access DB and coord systems

I have a table in access with lat and long.  I can create and successfully
Test Connection to the ODBC database which is identified as LL83.  I can
create a layer, a map and a web layout that will show this data.  If I set
my map coord system to UTM zone, the data is not transformed.  I can add
shape and sdf layers that are LL83 source and reproject just fine.  Only DB
data sources don't seem to want to reproject.

 

Can anyone offer any reason or advice?

 

Thanks

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