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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

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