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.
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.
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
Sheroid Clarke 1866
Return to NewsMagazine #15 Index