[Mapserver-users] raster query

[Lawrence, Kevin]

Yes  
I have been doing raster query for a couple of years.  This was the main
reason we used mapserver in the first place.  We use perl and mapscripts (a
little slower in some ways).  Actually the query is done in perl (C if you
want it to be faster).  We store the grids as arc/info GRIDFLOAT format for
query and a tif format for display.  using the header information for the
gridfloat we calculate which cell is being sampled and jump into the grid to
that cell.  The value is a 32bit work which can be simply converted and
returned as output.  We are able to apply look up tables to classified data
and get back a textual responses on a grid as well.

The concept can be moved to different fgrid formats and work just as well.  
Check out a specific example at
http://g4.glfc.cfs.nrcan.gc.ca/makemap.pl?layers=1952,8652,53859,2057,4240&t
itle=Abies+balsamea 


Kevin Lawrence
GIS analyst
1219 Queen Street East
Sault Ste. Marie
Ontario  P6A 2E5
ph: (705) 541-5600
email: klawrenc at nrcan.gc.ca

> ----------
> From: 	Frank Warmerdam[SMTP:warmerdam at pobox.com]
> Sent: 	Tuesday, November 25, 2003 3:03 PM
> To: 	mdoggett at coas.oregonstate.edu
> Cc: 	mapserver-users at lists.gis.umn.edu
> Subject: 	Re: [Mapserver-users] raster query
> 
> Matt Doggett wrote:
> > Been a while since this question has been asked...  Has anyone had
> > success in performing gridcell queries on raster layers?
> 
> Matt,
> 
> This still doesn't exist though there is a feature request filed for
> it in Bugzilla.  There is talk that DM Solutions may drive it's
> implementation in the coming months.
> 
> Best regards,
> 
> -- 
> ---------------------------------------+----------------------------------
> ----
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
> 
> 
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