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<br>Hi Rob,
<p>My answers are below your questions. However, if you like, go
ahead and
<br>give me a call at the office. We worked with a couple of very
similar projects
<br>to the one I think you are describing. My number is 254-710-6814
<p>Bruce
<p>--
<br>Bruce Byars
<br>Hydrologist and Senior Research Scientist
<br>CAGSR - GRASS Dev. Team - Baylor University
<blockquote TYPE=CITE> <font face="Arial"><font size=-1>I am considering
developing a package that will calculate signal reception for specific
stations using the Longley Rice Irregular Terrain Model. I need vector-topo
data for the entire country.</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>First, do you have to use vector data?
Can you use rasters and then script up r.mapcalc,</font></font>
<br><font face="Arial"><font size=-1>r.los, and r.binfer to perform your
analysis? Raster data may be easier to work with from</font></font>
<br><font face="Arial"><font size=-1>your description. Vector topo
map for the entire country will be BIG. Gigabytes. We already</font></font>
<br><font face="Arial"><font size=-1>have the US DEM's assembled, rectified,
and cleaned up and at 90m grid resolution the DEM</font></font>
<br><font face="Arial"><font size=-1>is about 2 gigabytes (raster data...I'll
calcualte the vector for you tomorrow).</font></font>
<br><font face="Arial"><font size=-1></font></font>
<br><font face="Arial"><font size=-1></font></font> -------------------------------------------------------<font face="Arial"><font size=-1>1.
What are my options this data? I suppose that I should use the DEM
data from USGS?</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>You can produce vector data from the
USGS DEM data without any problem using the</font></font>
<br><font face="Arial"><font size=-1>r.poly tool.</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>------------------------------------------------------------------------------------</font></font> <font face="Arial"><font size=-1>2.
Are there C or Perl libraries for working with DEM's? Specifically,
to use Longly Rice, I have to resample the vector data to generate an elevation
profile between two arbitrary points from the vector-topo data. Any
ideas on that either?</font></font>
<br>Personally, I think you will be better off cutting raster transects.
Tools are already in GRASS
<br>to do this.
<p>---------------------------------------------------------
<br> <font face="Arial"><font size=-1>3. When I am done I my
data will be <long>,< lat>,<reception index>; which I plan on
treating as a height field. What Grass tools can I use to create
an image from height field data.</font></font> <font face="Arial"><font size=-1>You
can create a raster "elevation" map of your surface with no problem.
To create</font></font>
<br><font face="Arial"><font size=-1>nice visualizations, use NVIZ or possibly
d.3d</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>-------------------------------------------------------------------------------------</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>4. Also, are there any books
out there to jumpstart someone who knows things like MapInfo, and Linux,
but not Grass??</font></font><font face="Arial"><font size=-1></font></font>
<p><font face="Arial"><font size=-1>We have a brand new tutorial that will
be ready this week.</font></font></blockquote>
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