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curt 2005-12-19 15:52:05 +00:00
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README
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@ -21,6 +21,15 @@ smaller chunks is much more doable though.
Building the Tools
==================
IMPORTANT: if you are compiling with gcc, I recommend that you compile
the /Libs/TriangleJRS code without optimization (-O2). Optimization can
lead to problems for some tiles. (Different numerical stability properties
in the optimized code????) Usually I will go and remove the -O2 option (twice)
from the Makefile after it has been generated from the Makefile.am file. Be
warned that any time you change the Makefile.am, or rerun autogen.sh or
configure, you will have to go back and fix this particular Makefile.
These tools are primarily compiled and tested under Unix with the Gnu
C/C++ compilers. I believe they also build and run on windows with
Cygwin. If anyone has patches for supporting other platforms, I will
@ -74,11 +83,11 @@ TerraGear supports several terrain data sources:
b) Then process the resulting files with "Prep/DemChop/demchop"
4. SRTM (1 and 3-arcsec nearly world wide coverage):
4. SRTM (version 1 & 2) (1 and 3-arcsec nearly world wide coverage):
ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/
a) Chop up the .zip files using "Prep/DemChop/hgtchop"
a) Chop up each .zip files using "Prep/DemChop/hgtchop"
5. 3-arcsec ASCII DEM files:
@ -95,7 +104,24 @@ TerraGear supports several terrain data sources:
The result for any of these terrain sources should be a "work" tree
with a .arr.gz file for each FG tile.
6. After you create the .arr.gz files you have to create a
6. SRTM data comes with 'voids'. These are areas where their
automated data processing system could not reliably determine the
elevation. Often this happens over water, or over mountain peaks.
There is a big chunk of the Grand Canyon missing, a big chunk of
Rhode Island, etc.
So as a partial fix I came up with a little program that will fill
in the voids from another data source. In this case the only thing
I half trust is the USGS 3 arcsec DEM data for the USA. So we
can't fix voids outside the USA right now.
In the same directory as DemChop and HgtChop there is a "fillvoids"
program. You might wish to run it with something like the
following command line:
find /export/fgfs05/curt/Work/SRTM2-North_America3 -name '*.arr.gz' -exec ./fillvoids {} /stage/fgfs05/curt/Work/USGS-DEM-USA-3 \;
7. After you create the .arr.gz files you have to create a
corresponding .fit.gz file for each of these. This is a data
reduction step which fits a set of polygons to the raw terrain with
a set of constraints on the maximum error allowed relative to the