SRTM PROCESSING - ENVIRSI - ENVI Version 1: BEFORE
GETTING STARTED:
Download SRTM data from ftp://edcftp.cr.usgs.gov/pub/data/srtm/ For GMT users, ENVI Runtime includes an SRTM import function
which preserves the 3-second interval value required for GMT's xyz2grd command.
(Ex. xyz2grd srtm3.dem -Gsrtm3.grd -I3c/3c -R34/37/90/97 -ZTLh -N-32768) IMPORT
ELEVATION FILE
-On the ENVI command bar -Click on File > Open External File > Digital Elevation > SRTM DEM -Navigate to the SRTM data directory > shift-click *.hgt files to load -Command prompts you for filling missing data points >
select Yes (ALT +Y) Warning: importing a .hgt file which has been previously processed in ENVI will
permanently corrupt the data. MOSAIC
ELEVATION DATA
-On the ENVI command bar -Click on Basic Tools > Mosaicking > Georeferenced -On the Map Based Mosaic panel -Click on Import > Import Files
and Edit Properties... > LMB select input files > Ignore -32768 -Press OK (multiple tiles will fill
the ignore value automatically). The mosaic definition and projection information should appear on the
Mosaic panel's title bar. -Click File > Apply > Save *.dem
file (name & extension is arbitrary, of course). Output file will appear in Available Bands List panel. Open
to verify mosaic operation is complete. At this point, the file is ready for
import into GMT. For ArcGIS users, verify that you have the ENVI reader for
ArcGIS loaded. You can download a free copy at http://www.rsinc.com/download/. Be sure to rename your *.dem to *.dat. Otherwise, after the mosaic definition can be applied
using ENVI's virtual mosaic parameters. -Click File > Save Template... Save *.mos file -On the ENVI command bar -Click on File > Save File As > TIFF/GeoTIFF > Save
*.tif file
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