[GRASS-user] SRTM data aliases in UTM

[John Stevenson]

Hi,

I have imported some tiles of 1 arcsecond SRTM data into GRASS 6.3 using 
r.in.srtm into a lat-long region.  Whenever I import them to a UTM 
region, res=30, I get aliasing problems.  This results in a grid of 
lines of jumps in elevation running through my data.

This happens when I use r.proj.  I have also tried generating a text 
file of UTM coordinates via r.stats -1g, and cs2cs.  Importing this as a 
raster or vector, and interpolating with r.surf.rst or v.surf.rst also 
give aliasing errors.

What is the best way round this?  Importing at a higher resolution?  How 
much higher?  My ultimate aim is to compare the SRTM with LiDAR data, so 
if possible I would like to use an exact interpolation where possible.

Cheers

John

-- 


Dr John Stevenson
Postdoctoral Research Associate
School of Earth, Atmospheric and Environmental Sciences
Williamson Building (Room 2.42)
University of Manchester
Manchester M13 9PL, UK
tel. +44(0)161 306 6585; fax. +44(0)161 306 9361;
john.stevenson at manchester.ac.uk