[Mapserver-users] DTED Mapping Data

[Frank Warmerdam]

James Anderson wrote:
>  
> Hello,
>  
> I have a big problem.   I have been sent a lot of DTED data, extention 
> .dt1, also some .cov files.   I have since found out that this is U. S. 
> Department of Defense Digital Terrain Elevation Data, which is some sort 
> of three dimensional spacial data.  I have no idea how I am supposed to 
> convert this data or get it to work with the mapserver.  Currently this 
> does not look good, and I am under a lot of pressure from my work to 
> produce something with it.
>  
> Currently I need the data to work in Mapserver.   I also have Mapinfo 
> professional 6.5 which I could perhaps use for something, but it does 
> not seem to support .dt1 data.  If there is a way to convert this data 
> to tab or shape files, or for mapserver to work with it directly, then I 
> would be very very very happy.

James,

DTED is a raster format, and is currently supported by GDAL if you have
a mapserver build with GDAL support.  But the data is 16bit, not 8bit, so
you will need to use some scaling to 8bit for visualization.  Adding a
PROCESSING "SCALE=AUTO" declaration is likely sufficient to start though
you might want to review the section on scaling at some point.

However, you indicated an interest in converting the data to tab or
shapefiles.  This leads me to suspect you want to see contours or something
similar.  If so, you will need to do some pre-processing.  The development
version of GDAL includes a new utility for producing contour vector data from
elevation data that might be of some use.  Lots of other packages can do
similar things.

Note, if you have many DTED files, it likely makes sense to use a tile index
for them so you can treat them all as one layer.  If you do this, using
fixed scaling likely makes more sense otherwise different scaling may be used
for different source files displayed in the same map view which would be
confusing.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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