read_SRTMtile

reads an SRTM (Shuttle Radar Topography Mission) 3-arc second file

read_SRTMtile: returns lon, lat, & height (height in meters) from SRTM 3-arcsec data

USE: [vlon vlat vhgt] = read_SRTMtile(filename,sc)

INPUT:
1) filename: filename, e.g. 's23w041.hgt'
the 3-arc sec files can be found at:

http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/

2) sc: spot check, any value here will produce a low resolution image of tile (note: image rendering can be time consuming)

OUTPUT:
vlon: column array of cell longitudes
vlat: column array of cell latitudes
vhgt: column array of cell heights (in meters)