Raster Analysis and MapServer

Aaron Racicot aaronr at ECOTRUST.ORG
Mon Dec 19 18:54:52 EST 2005

Hi there Brian,

I do just this type of stuff all the time.  We use this type of
"workflow" for web-based decision support tools, with Mapserver on the
front end and GRASS on the back end.  I can talk to you more about this
offline if you want, but the basic idea is to create an "on the fly"
GRASS work area in a sessions temp directory and run grass from a
scripting language based on user input from Mapserver.  I use PHP and
have developed a little PHP object structure that emulates the "batch
GRASS" type structure to allow for doing raster manipulation via
r.mapcalc.  All in all it is fast and pretty straight forward once you
have done it a couple of times.  We have done raster display directly
from GRASS, but tend to output to other formats for display in Mapserver
for many reasons.  Again, there are probably others out there doing
similar or other unique things to get the job done, but I am more than
happy to talk to you more about how I go about implementing a web-based
real time stack via Mapserver and GRASS.

Hope this helps to get you going!


| Aaron Racicot  | aaronr at ecotrust.org   |
| GIS Programmer | 503.467.0759          |
| e c o t r u s t                        |
| Jean Vollum Natural Capital Center     |
| 721 NW Ninth Avenue                    |
| Suite 200                              |
| Portland, OR 97209                     |
| www.ecotrust.org                       |
-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Fischer, Brian
Sent: Monday, December 19, 2005 3:38 PM
Subject: [UMN_MAPSERVER-USERS] Raster Analysis and MapServer

MapServer users,
I have a project that I would like to generate raster data on the fly
and use MapServer to display the results.  I am curious if anyone else
has tried this.  If so what tools did you use to do the raster analysis
and how did it work?  Let me explain more about the process.
1. Someone would go to a web page and click a button to start the
2. Some tool would create raster1 from a line vector file (contours)
(need a contour to raster algorithm)
3. Some tool would do a raster calculation (raster1 minus raster2) to
produce a final raster
4. MapServer would display the final raster.
I need all of this process to happen over the web.  I think I can use
GRASS to do the raster analysis, but I am curious if anyone else has
done this sort of thing.  My other option is to go to ESRI's
ArcGISServer (which I don't want to do, if I don't have to).  Are there
any other tools available to do raster analysis (spatial analysis) on
the web?
Any insight would be helpful.
Brian Fischer, GIS Specialist/Programmer
Houston Engineering, Inc. | Leave Nothing to ChanceTM
10900 73rd AVE N, Suite 106
Maple Grove, MN 55369
Phone:  763.493.4522 / Fax:  763.493.5572
Email:  bfischer at houstonengineeringinc.com
Website: www.houstonengineeringinc.com 

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