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Re: Converting distance to degrees [message #76532]

Fri, 17 June 2011 01:44

Klemen
Messages: 80
Registered: July 2009

Member

Ashely,

the data you have are projected and transformation into another
projection is not as easy as it seems. You have to first find out, in
which map projections are your data. Check metadata, ask the data
creator... Perhaps such a link might help:
http://egsc.usgs.gov/isb/pubs/MapProjections/projections.htm l

Then:
1. Use MAP_PROJ_INIT to define a structure for definition of your map
projection.
2. Transform the location of your data from Chartezian XY into
ellipsoid LON LAT coordinates using MAP_PROJ_INVERSE.
As your original data are quite detailed comparing to the results you
might think of aggregating your original data into e.g. 25 km grid
first. This will speed up the gridding in step 3 significantlly.
3. Grid the data using TRIANGULATE and GRIDDATA. In both cases use /
SPHERE option.

See also this discussion:
http://groups.google.com/group/comp.lang.idl-pvwave/browse_t hread/thread/688e9587fa29ecb7/2f7820d787d6047f?hl=en&q=# 2f7820d787d6047f

Cheers, Klemen

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[Message index]

		Re: Converting distance to degrees By: Klemen on Fri, 17 June 2011 01:44
		Re: Converting distance to degrees By: Ashley Berg on Thu, 16 June 2011 10:49
		Re: Converting distance to degrees By: Kenneth P. Bowman on Thu, 16 June 2011 06:32

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