| Re: IDL Procedure to read/write USGS DEMs [message #17295] |
Wed, 29 September 1999 00:00 |
Kelly Dean
Messages: 92
Registered: March 1997
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Member |
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Reading DEMs are pretty simple. Below is an sample of a routine I used to
read the GTOPO30 Elevation data from the CD. Swapping is required if you
are on a PC.
Kelly Dean
CSU/CIRA
========================Colsm.pro=========================
PRO COLsm
;
; Retrieve an area around Colorado
;
topo = INTarr(4800,6000)
OpenR, 1, 'e:\w140n90\w140n90.dem', /swap_endian ; Swapping required on PCs
ReadU, 1, topo
Close, 1
; Rotating not really required, IDL displays from bottom to top. Just my
preferred method.
topo = ROTATE(TEMPORARY(topo),7)
toposmall = topo(4150:4249, 0:99) ; Retrieve Colorado
SHADE_Surf, toposmall, shades = BYTscl(toposmall), ax=83, az=0
LoadCT, 11
END
=========================================================
John Brock wrote:
> I am working on integrating topographic data at various spatial
> resolutions within a single
> USGS 7.5 minute DEM. This requires changing the data structure for a
> DEM to
> handle sections of variable resolution.
>
> Does anyone know of an existing IDL procedure that reads or writes USGS
> DEMs?
> (DEM = digital elevation model). If so, I would like to use it as a
> starting point.
>
> Thanks,
>
> John Brock
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