Proceed to GeoCommunity Home Page


SpatialNewsGIS Data DepotGeoImaging ChannelGIS and MappingSoftwareGIS JobsGeoBids-RFPsGeoCommunity MarketplaceGIS Event Listings
HomeLoginAccountsAboutContactAdvertiseSearchFAQsForumsCartFree Newsletter

Sponsored by:
TOPICS
Today's News

Submit News

Feature Articles

Product Reviews

Education

News Affiliates

Discussions

Newsletters

Email Lists

Polls

Editor's Corner


SpatialNews Daily Newswire!
Subscribe now!

Latest Industry Headlines
DMTI Spatial Joins the BlackBerry ISV Alliance Program
GGP Transforms Planning Information in Rother
ESRI's New ArcGIS API for Flex Improves the Look and Feel of Web Mapping Applications
TomTom Sets New Standard for Navigation Industry
NGA Debuts New Public Website
MiTAC Extends Relationship with Tele Atlas to Provide Digital Maps

Latest GeoBids-RFPs
Surveying Equipment-Canada
Satellite Tool Kit
GIS Database-FL
Training Development-UT
Various Sources Sought-FL

Recent Job Opportunities
GIS Specialist
GIS Analyst
Information System Application Developer
GIS/GPS technician
GIS Technician
Senior Research Analyst
SR. INFORMATION TECHNOLOGY ANALYST (GIS)
Geographic Information System Map Technician
GIS Specialist
GIS Analyst / Coordinator

Recent Discussions
Hosting costs - ArcServer
GIS Viewer and Linux
Copan -- Free coordinate geometry software
NED's and Autodesk Map 3D 2009
Geo-Spatial
Contents | Solid Waste | Metadata | New GIS Products |UNIGIS | WebMapping | Free Data
Free Software | Canada | Events | TechTip | Grads | GeoSpatial 101

Tech Tip - Reprojecting California DRGs

In a recent post to a popular ArcView discussion list, Bob McLaughlin noted a common problem encountered when working with USGS DRGs available from the GISDataDepot or the USGS. He downloaded several files from The GISDataDepot website:

One is a 1:100,000 DRG with the following world file:

10.160000000000
0.000000000000
0.000000000000
-10.160000000000
497423.048936912615
4430747.867833577096
He then projected some polygon shape files to the appropriate UTM zone to match the DRG. He opens both the polygons and the DRG and, success, a perfect overlay. 
1.52787825968654 
0.00000000000000 
0.00000000000000 
-1.52787825968654 
-237517.47266643188777 
168824.16153494617902
He opens the same polygons used with the 1:100,000 DRG and now get a total mismatch. Obviously, the 1:24,000 DRG was scanned using different units, or projection, or something else less obvious.

SOLUTION:
He was indeed using 1:24,000 DRGs for California, which are in the custom Teale Albers projection. Once he projected the shape files to these settings, he got the correct overlay. Dave LaPlante kindly provided the paramenters for the Teale California Albers projection, which are included below for all who are interested.

projection                  albers
units                       meters
1st standard parallel       34 00 00
2nd standard parallel       40 30 00
Central Meridian            -120 00 00
Latitude of Origin          00 00 00
False easting (meters)      0
False northing (meters)     -4000000
Datum                       NAD27
Sheroid                     Clarke 1866

Return to NewsMagazine #15 Index


Sponsored by:

For information
regarding
advertising rates
Click Here!
Copyright© 1995-2008 MindSites Group, LLC / Privacy Policy

GeoCommunity™, Wireless Developer Network™, GIS Data Depot®, and Spatial News™
including all logos and other service marks
are registered trademarks and trade communities of
MindSites Group, LLC