[TCMUG] How do you match up two datasets?

Brian Fischer bfischer at houstoneng.com
Thu Aug 19 11:41:43 EDT 2010


Ian,
Coming at it from a time perspective, I would want to just to remove the old stuff and replace it with the new stuff.  There maybe a few cases where someone updated a road centerline in OSM that is not in the new GIS dataset, but in my opinion this would be pretty rare and it would take forever to compare each line one by one on an import.  The counties do a good job keeping the road centerlines accurate because they have to for E911 purposes.  At least for horizontal accuracy, names and even address ranges.  The exception might be if an OSM users adds a tag like speed limit.

I would much rather see OSM have 98% of the road centerlines by correct for MN and see the update taking minimal time versus trying to compare every line for accuracy and having the process take years.  I only think this is a valid point for road centerlines.  I think there are other datasets that you would not want to take this approach in OSM like place of interest points, parks, buildings, etc.

If you want me to get you a County road centerline file let me know, I'm sure I can come up with some county in MN (maybe Douglas, Rock or McLeod) that I could give to you.  This might be a good way to test your methodology for an import tool, at least with road centerlines.

Just my 2cents.

Brian Fischer, CFM  GIS Project Manager
Houston Engineering, Inc.
Phone: Direct: 763-493-6664 / W: 763.493.4522 / M: 763.229.2734

From: tcmug-bounces at lists.osgeo.org [mailto:tcmug-bounces at lists.osgeo.org] On Behalf Of Ian Dees
Sent: Thursday, August 19, 2010 10:29 AM
To: tcmug at lists.osgeo.org
Subject: [TCMUG] How do you match up two datasets?

Hi TCMUG,

I've been pondering a way to help people import into OSM while respecting the existing data. To that end, I'm wondering if anyone on the list could talk about how they would go about applying one (newer, presumably better) dataset to another. I'm thinking of the usecase where MetroGIS has old street centerline data from 1990 and receives an update from 2010. How would you go about doing that? What tools would you use and what are they called?

I'm envisioning a web map that allows you to view the new data as an overlay on the existing data, marking whether or not to import each new feature and how the import should happen (completely remove old stuff and replace with new stuff, update the metadata on the old stuff with the new stuff, or something else). However, when there are a gazillion things to import, it might not make sense to do that one-by-one.

Thanks for your thoughts!
Ian
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