The program extension Projector!, part of the 3.0a upgrade for ArcView, can be used to
project data into standard or custom projection systems. The ArcView 3.0a upgrade is
currently available from Environmental Systems Research Institute (ESRI) at
After downloading the upgrade kit, follow the "readme" instructions for
installation the kit will find the main ArcView program and run a series of fixes on it
and add the new features. After installation is complete, look at the ArcView directory.
It should include:
The upgrade kit normally places the new extensions in a subdirectory of "samples" called ext. Grab the files from "ext" and move them into the ext32 directory, or you won't be able to find the new goods easily from within ArcView.
To access the extensions, launch ArcView, choosing "ArcView 3.0a patch". Under the main file menu, choose extensions. A pop-up window will appear listing several dozen programs, including Projector. Click the box for Projector or any features you want enabled. When you bring up a new view, a button is added to the top menu bar, toward the right side. This button (showing an upward arrow in a circle with four corner points) launches the Projector! program. Before you can convert data, you must:
1. Add the data theme that you want to convert and select it as the active theme. 2.
Specify the view units of measurement (decimal degrees for unprojected data). This is
under: View
Properties
Map Unit
When projecting decimal degree data into UTM, the first window will ask for your desired output measurement units. Select meters. The next window offers a variety of projection options. If you wand to view your point data with scanned quad or airphoto imagery, you will need to know which datum was used in preparing the imagery files - NAD 27 or NAD 83. Arc View uses the more recent datum as its default, so if your imagery also uses the more recent datum, you can choose a standard projection, such as UTM zone 15. If your imagery uses the older datum (such as DRGs or scanned quadrangle maps) you will need to set up a custom projection. The parameters to enter for a UTM projection with the older datum are:
| Zone 14 (102 - 96 degrees) | Zone 15 (96-90 degrees) | Zone 16 (90-84 degrees) | |
|---|---|---|---|
| Projection | Transverse Mercator | Transverse Mercator | Transverse Mercator |
| Spheroid | Clarke 1866 | Clarke 1866 | Clarke 1866 |
| Central Meridian | -99 | -93 | -87 |
| Reference latitude | 0.00 | 0.00 | 0.00 |
| Scale factor | 0.99960 | 0.99960 | 0.99960 |
| False Easting | 500,000.00 | 500,000.00 | 500,000.00 |
| False Northing | 0.0000 | 0.0000 | 0.0000 |
Projector! will convert the data and will add a new shapefile to the view that you select. It will ask you to provide a name and target directory for the new shapefile.
To convert projected data to another projection, you must know the specific projection parameters originally used for the data you want to convert. Projector! uses a two-phase conversion for projected data: it asks for the original measurement units and projection parameters as "inputs", and allows you to specify new measurement units and projection parameters as "outputs". A simple example is conversion of a shapefile from one UTM zone to another.
After highlighting the shapefile to convert in the legend bar, and setting the
measurement units in "View"-"Properties", click on the button for
Projector!
Enter input measurement units - meters.
Enter input (existing) projection parameters as a custom projection.
| Zone 14 (102 - 96 degrees) | |
|---|---|
| Projection | Transverse Mercator |
| Spheroid | Clarke 1866 |
| Central Meridian | -99 |
| Reference latitude | 0.00 |
| Scale factor | 0.99960 |
| False Easting | 500,000.00 |
| False Northing | 0.0000 |
Enter desired output measurement units - meters
Enter desired output projection parameters as a custom projection.
| Zone 15 (96 - 90 degrees) | |
|---|---|
| Projection | Transverse Mercator |
| Spheroid | Clarke 1866 |
| Central Meridian | -93 |
| Reference latitude | 0.00 |
| Scale factor | 0.99960 |
| False Easting | 500,000.00 |
| False Northing | 0.0000 |
Select a name and target directory for your new shapefile.
While Projector! May not be able to handle conversions involving data with highly customized original projections, it seems to work well for fairly standardized ones. Within the projection parameters window, one can see which parameters this extension uses as defaults for a wide variety of projections by selecting the standard button. Of note, the above example proceeds using the "custom" option because the standard spheroid used in Projector! is GRS 80, rather than the Clarke 1866. Many of the DRG files currently available from USGS are registered to the older datum using the Clarke 1866 spheroid.
For additional information regarding this Web page, contact Deb Southworth Green, in the Division of Information Technology Management, at Deb_Green@fws.gov
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Keywords=GIS, data, projections, ArcView
Last Modified January 08, 2001 10:21 AM