Re: ElevationGrid

[Mike McCann <mccann@mbari.org>]

Theresa-Marie Rhyne wrote:
> 
> Hi Bob:
> 
> "(1) Do folks in the geo community actually use
> height field maps, or is this something that's
> pretty much in the domain of modelers and
> raytracers?"
> 
> -- yes height field maps are used.
> 

An example I've used is output from ArcView that looks like
this:

ncols         82
nrows         58
xllcorner     548681.904174
yllcorner     4042161.445462
cellsize      1000
NODATA_value  -9999
-110.25 -108.5625 -108.3125 -108.875 -103.8125 -95.75 -89.625 -84
-78.625 -72.5 -69.875 -65.8125 -61.25 -56.25 -49.75 ....
... (82x58 numbers representing the elevation)

These data make a nice mapping into the ElevationGrid node, though
we have to create a new origin (offset) for the UTM coordinate 
system, which are the xllcorner & yllcorner numbers.

I've seen this format use a lot by marine geologists, who would
then like to place real image data, such as acoustic reflectivity,
over the terrain.  These images are co-located with the terrain
data within the ArcView tool.

-Mike

-- 
Mike McCann                         | E-mail: mccann@mbari.org
Monterey Bay Aquarium Research Inst.| Phone: (408) 775-1769
PO Box 628 (7700 Sandholdt Road)    | Fax:   (408) 775-1620
Moss Landing, CA 95039-0628         | URL: http://www.mbari.org/~mccann