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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | GISList: RE: Redefining projections for geodatabases |
| Date: |
06/02/2003 12:20:01 AM |
| From: |
Tina Brister |
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Hi Analisa,
The coordinate information on an existing feature dataset CANNOT be modifie=
d. There is no way to accurately reproject your data when its being stored =
in an inaccurate coordinate system and/or unit of measure.=20
1. EXPORT- Try exporting your geodatabase feature classes to shapefiles (ra=
ther than coverages).=20
2. REDEFINE- The shapefile format will enable you to modify a unit of measu=
re on an existing dataset. Use ArcCatalog to set the coordinates. [Open Arc=
Catalog. Right-click on the shapefile. Select Properties. Click on Fields t=
ab. Select the Shape field. Under Field Properties, there is a gray ellipse=
box next to Spatial Reference. Click that. Select the coordinate system (N=
AD 83) that contains the correct unit of measure (International Ft). I'm un=
sure which coordinate system would be using International Ft., but I am ass=
uming you know if you have changed the coverage.]
3. REPROJECT- Import the newly defined shapefiles into a new feature datase=
t that contains the coordinate information you want (ie NAD27). You should =
not lose any attributes.
Hopefully that helps.
Cheers,
Tina
=20
-----Original Message-----
From: Analisa Gunnell [mailto:analisa@ecotrust.org]
Sent: Sunday, June 01, 2003 8:14 PM
To: gislist@geocomm.com
Subject: GISList: Redefining projections for geodatabases
Hello List,=20
I am working with an Arc 8.3 geodataset that needs to have its projection m=
odified from NAD83 US FEET to NAD83 International feet (an unfortunate proj=
ection mishap at the beginning of my digitizing from aerial images that we =
were told were in US feet), and then reproject the layers into NAD27. Does=
anyone know how to do this while still working within a geodatabase? I've=
tried, unsuccessfully, to modify the projection of my feature dataset, but=
this does not give me the proper projection after I reproject the data int=
o NAD27. The only way that I've been able to get my data to match the proje=
ction of the images that are in NAD27, is to export them to coverage's and =
then manipulate the projection from there. However, I am losing attributes=
of my data, which is, obviously, unacceptable. Any, and all suggestions a=
re greatly appreciated in advance.=20=20
Sincerely,=20
Analisa Noel Gunnell=20
GIS Technician=20
Ecotrust=20
721 NW Ninth Avenue, Suite 200=20
Portland, Oregon=20
97209=20
503.467.0750
analisa@ecotrust.org=20
www.ecotrust.org=20
www.inforain.org
CONSERVATION ECONOMY
ECOLOGY-ECONOMY-EQUITY
=A0
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