[GRASSLIST:1143] Converting DRG Albers to UTM

Jeshua Lacock jeshua at SierraMaps.com
Thu Nov 16 19:01:29 EST 2000

Hello all,

Being completely new to grass, I am having a hard time figuring out an appropriate method to convert a USGS DRG from Albers projection to UTM.

The DRG has a .tfw forld file in Albers coordinates.  The .tfw file only has coordinates for the South-East corner and the meters per pixel value.

So would I set up my database in UTM or Albers?  How do I associate the .tfw world file with the DRG?

When I attempted to set up the Albers projection parameters, I was prompted to enter a value for the Central parallel.  I was not given a Central parallel parameter, just the 1st and 2nd standard parallel values.  Here are all of my known Albers projection parameters:

 units:                                   meters
 1st standard parallel        34 00 00      (would this be 34N?)
 2nd standard parallel      40 30 00
 Central Meridian             -120 00 00    (would this be entered as 120W or -120 ?)
 Latitude of Origin              00 00 00
 False easting                    0
 False northing                   -4000000
 Datum                                 NAD27
 Sheroid                               Clarke, 1866

Note that I did not notice anywhere to input the "False nothing" or "False easting" values.

Does anyone know how I can figure out what the value for the Central parallel?

Sorry for so many questions!!  I would greatly appreciate an outline of suggested events to complete this re-projection.

Thanks in advance,

Jeshua Lacock
Telephone: (760) 935-4481

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