[Mapserver-users] best way to color ramp topo/bathy data that's in PostGIS

[Jan Hartmann]

Hi Charlton,

I've been using GRASS/MapServer on a few 30sec global databases 
(elevation, satellite, landcover, going to show them on the User's 
Meeting). In my experience, putting everything in a GRASS database and 
displaying them directly from there in MapServer is the most efficient 
way. It's quick, lets you manipulate your rasters (e.g. colortables) in 
GRASS while immediately displaying them in MapServer, makes it 
incredibly easy to create tiles and tileindexes, etc. As to your other 
suggestions: I don't think PostGIS already has raster support, and the 
maximum number of classes in MapServer is 50 by default. You can compile 
in a larger number, but you'll get horrible mapfiles.

Some time ago, Frank Warmerdam wrote about the possibility of color 
table processing in GDAL 
(http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0304/msg00621.html). 
Is this something for a feature request? I think there are many people 
who could use such a feature.

Jan

Charlton Purvis wrote:
> Hi, folks:
> 
> I've got an approach question to ask.  I've been boning up on GRASS and
> r.colors and MapServer integration.
> 
> Say I'm updating my PostGIS data based on :15 minute pings of netCDF
> DODS-available data.  In these datasets is some interpolated bathymetry
> data.  What is the best way for me to store and then render it?
> 
> We're already going from netCDF to PostGIS.  I don't think I really want
> to break my .map into a lot of classes (255?) to display a nice and
> gradual color ramp for different sea depths.  So should I be pumping my
> PostGIS data into GRASS and somehow doing an r.colors on it to then be
> displayed by MS as a raster dataset?  Or should I be trying to take
> advantage of the alpha (?) GRASS version which already talks PostGIS (I
> think I heard that somewhere)?  Or should I spend a little bit of time
> making a large .map file that contains many layers w/ unique RGB's?
> 
> Truth be told, I think the less pieces, the better.  I'd love to keep it
> all wrapped up in MapServer.  But I'm trying to bone up on GDAL, too
> however, I don't quite see where that fits in.
> 
> Any help always appreciated.
> 
> Thanks.
> 
>  
>  
>  
> Charlton Purvis
> (803) 777-8858 : voice
> (803) 777-8833 : fax
> cpurvis@sc.edu
>  
> Advanced Solutions Group
> Department of Physics and Astronomy
> University of South Carolina
> Columbia, SC 29208
> 
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