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Georeferencing Errors [message #41513]

Tue, 02 November 2004 10:20

will.mccarty
Messages: 2
Registered: November 2004

Junior Member

OK, I've posted on this before, and this time I'm using a bit of a
more common dataset (GTOPO30 terrain elevation), but getting similar
geolocation errors. Thus I'm interested in seeing what (if anything)
you guys can come up with. I use the following code:

--test_lat_lon.pro
ulx = -99.99583333333334
uly = 39.99583333333333
dx = 0.00833333333333
dy = 0.00833333333333

lat = fltarr(4800,6000)
lon = lat
for i = 0, 4799 do begin
for j = 0, 5999 do begin
lat[i,j] = uly - dy*j
lon[i,j] = ulx + dx*i
endfor
endfor

openr,1,'W100N40.DEM'
z = intarr(4800,6000)
readu,1,z
close,1

z = swap_endian(z)
map_set,mean(lat),mean(lon),/cylindrical,limit=[min(lat),min (lon),max(lat),max(lon)],/noborder

rmz = map_patch(z,lon,lat,missing=-9999)
tvscl,rmz
map_continents
end
---end

to put the topographic info to a projection. The result is at
http://vortex.nsstc.uah.edu/~mccarty/georef-err.png. Clearly there
are some georeferencing errors. I've tried both idl 5.6 (my normal
version) as well as 6.0. Similarly, I've tried multiple projections.
I've got some theories, but i'm looking to the experts on this one.

Thanks for any help you folks can provide.

Will

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[Message index]

		Georeferencing Errors By: will.mccarty on Tue, 02 November 2004 10:20
		Re: Georeferencing Errors By: Kelly Dean on Wed, 03 November 2004 21:21
		Re: Georeferencing Errors By: will.mccarty on Wed, 03 November 2004 12:19

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