# GDAL commands for assembling SRTM and ASTER DEM tiles associated with

# the 60N Canada boundary analysis, and resampling into the desired 3"

# (~90m) resolution even-boundary grid.

#

# These commands generate strips of elevation data (GeoTIFFs) along a

# 40-degree longitudinal extent matching (at least one of) Rick Reeves'

# mosaicked CDEM grids. The strips extend 150 pixels south of 60N and

# (in case of ASTER only) 150 pixels north of 60N, which should provide

# a sufficient but not excessive latitudinal range for fixing and

# assessing boundary artifacts.

#

# Note:

#   Working with the original ASTERs yields this warning from GDAL:

#     Warning 1: TIFFReadDirectoryCheckOrder:Invalid TIFF directory;

#     tags are not sorted in ascending order

#   I then ran gdal_translate on several of the offending ASTERs, then

#   repeated the vrt/warp on those -- now without warnings. However, the

#   output data was the same as when I operated on the original files

#   (with warnings), so for the moment I'm just going to ignore the

#   warnings.

#

# Jim Regetz

# NCEAS

# at the time of script creation, these paths were correct on vulcan

export ASTDIR="/home/reeves/active_work/EandO/asterGdem"

export SRTMDIR="/home/reeves/active_work/EandO/CgiarSrtm/SRTM_90m_ASCII_4_1"

# SRTM (also convert to 16bit integer)

gdalbuildvrt srtm.vrt $SRTMDIR/srtm_*_01.asc

gdalwarp -ot Int16 -te -136 59.875 -96 60 -ts 48000 150 -r bilinear \

  srtm.vrt srtm_150below.tif

# ASTER

gdalbuildvrt aster.vrt $ASTDIR/ASTGTM_N59*W*_dem.tif \

  $ASTDIR/ASTGTM_N60*W*_dem.tif

gdalwarp -te -136 59.875 -96 60 -ts 48000 150 -r bilinear \

  aster.vrt aster_150below.tif

gdalwarp -te -136 60 -96 60.125 -ts 48000 150 -r bilinear \

  aster.vrt aster_150above.tif

# note that the top 150 rows of this one are, somewhat surprisingly,

# slightly different from the above!

# gdalwarp -te -136 59.875 -96 60.125 -ts 48000 300 -r bilinear \

#   aster.vrt aster_300straddle.tif

#

# and this yields an even different set of values

# gdalbuildvrt aster_N60.vrt $ASTDIR/ASTGTM_N60*W*_dem.tif

# gdalwarp -te -136 60 -96 60.125 -ts 48000 150 -r bilinear \

#   aster_N60.vrt aster_150above.tif