Regina,
To use the approach below you need to 'Stop Editing' so that the union
edits are written to the shapefile.
However, I think an easier approach is to not use the GUI Editing
interface and rather the 'Dissolve' tool in the (Geoprocessing tool
reference > Data Management toolbox > Generalization toolset > Tools),
which will take and input datasource and output a new one through the
'ArcToolbox' dialog.
Here is the direct link to the tool help (should help you find it in
the Toolbox view):
http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Dissolve_(Data_Management)
A Happy-PosGIS-User-Once-A-Confused-Clicky-ArcGIS-User,
Dane
On Aug 18, 2008, at 9:02 AM, Obe, Regina wrote:
Thanks Mike,
Yap that looks more like a union and was pretty fast, but then
couldn't figure out how to export it.
I right clicked on the layer - selected export data to shape.
Very strangely when I reopen the new shape file in ArcMap - it looks
unioned, but then when I open the same shape file in OpenJump - I
can still see the boundaries still and opening up the dbf there are
clearly 274 records. I even deleted the mxd, sbn, sbx files ArcMap
created and it still looked unioned when I reopened it in ArcMap and
not unioned when I look at it in open jump.
The union created in open jump is half the size of the ArcMap one
too and dbf is empty as I would expect since I didn't ask for any
roll up of attributes.
I'm very puzzled. I have no idea why ArcMap shows this as unioned
when the size of the shape and the stats don't look that much
different from the original. I'm sure I must be missing something
here.
Stats looks like this is in open jump
Layer: OpenJumpUnion
Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 1
Min Max Avg Total
Pts 69795 69795 69795.0 69795
Holes 0 0 0.0 0
Components 219 219 219.0 219
Area 1104.3917345465716 1104.3917345465716 1104.3917345465716
1104.3917345465716
Length 733.4595414659133 733.4595414659133 733.4595414659133
733.4595414659133
ArcMap Union
Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 274
Min Max Avg Total
Pts 5 45836 688.0 188644
Holes 0 0 0.0 0
Components 1 219 1.0 492
Area 1.0783706500011592E-5 1104.373302353546 8.061118897843844
2208.7465780092134
Length 0.013284095041776186 733.3902842391406 8.213194606088345
2250.4153220682065
Original
Layer: st99_d00
Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 274
Min Max Avg Total
Pts 5 45836 688.0 188644
Holes 0 0 0.0 0
Components 1 219 1.0 492
Area 1.0783706500011592E-5 1104.373302353546 8.061118897843844
2208.7465780092134
Length 0.013284095041776186 733.3902842391406 8.213194606088345
2250.4153220682065
Signed,
Very confused Regina
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
] On Behalf Of Bresnahan, Mike
Sent: Monday, August 18, 2008 10:12 AM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] PostGIS 1.3.3 on Windows XP Unstable
> How the hell do you get it to do a real union?
Heh. Intuitive ArcMap is not. It took me forever to figure it out as
well. You can do a union a couple different ways. The way that
seemed to work the best for this is to:
1) Run ArcMap
2) Add the shapefile to your map
3) Open the edit toolbar.
4) Click on Start Editing.
5) Select the entire dataset by left clicking and then dragging a
rectangle around the geometry.
6) Select Union from the menu on the edit toolbar.
You should see the union happen right before your eyes.
I think I tried the Union Tool like you did and didn't get what I
expected. I think it just did a union on each individual feature
instead of doing an aggregate union.
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