[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
Cartographer/Owner
http://SierraMaps.com
http://3dTopoMaps.com
Telephone: (760) 935-4481
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