Friday, August 29, 2008

[Geomedia-l] Using GeoMedia to find shutoff valves for water mains‏

From: geomedia-l-bounces@directionsmedia.net on behalf of Alan Rich
Sent: Fri 8/29/08 11:49 AM
To: geomedia-l@lists.directionsmag.com

All,

A few weeks back, I asked if anyone had ever used GeoMedia to identify which shutoff valves should be turned off in the event of a water main break. My data consisted of water main line features and valve points snapped to the main lines.

Thank you very much to everyone that provided solutions to the problem.

That includes:
Bryan Clarke, Christchurch City Council, New Zealand
Jeff Hobbs, San Jose Water Company
Steve Hoffman, Intergraph Corp.
Pat Smith, Intergraph Corp.
Shahid Mujtaba, City of Milpitas GIS Volunteer


As it turned out, we ended up using parts of the various solutions in order to solve our problem. We had some data issues that kept us from using the provided solutions in their entirety. Shahid finally developed the workflow that we used. Here are the steps:

  1. Perform an Analytical Merge of the water main features using the “All” option.

  2. Create a small buffer zone (1 or 2 centimeters) around each valve

  3. Perform a Spatial Difference between the merged mains (output from 1.) subtracting the buffered valves (output from 2.)

  4. Take the output from 3. and apply Functional Attributes using the Geometries option.

  5. Take the output from 4. and apply an Analytical Merge using the Touching option.

  6. Take the output from 5. and perform an Aggregation using the output from 5. as the “Aggregate to summary features in”, and the buffered valves (output from 2.) as “From detail features in”, using “Touch” for the spatial aggregation. For the output, use the concatenate option specifying a comma for the separator and the valve id number to concatenate.

This will then allow the user to double click on a main which will expose the attribute window indicating which valve ids need to be turned off. The valve ids have previously been labeled on the map. This solution will allow us to use GeoMedia Viewer on field laptops to find which valves need to be turned off.

I plan to post this to both Shahid Mujtaba’s blog http://geomedia-analysis.blogspot.com and Jeff Hobb’s blog http://jeffhobbs.net.

Thanks again to everyone that offered advise. Your help made the difference!

Alan Rich
Geographic Information Systems (GIS) Manager
City of Milpitas
Milpitas, CA 95035


1 comment:

Shahid Mujtaba said...

This description is a clean concise easy to understand wokflow of only the necessary steps required to solve the problems. Further details on the solution are provided in detail on a prior post.