Zillow, CrowdSourcing and MapCruncher

Shortly after Zillow announced they are releasing their neighborhood boundaries, The Virtual Earth blog described how this data can be chopped up by MapCruncher into tiled vectors for more efficient display.

I don’t see a realistic editing workflow though.

Let’s pretend I’m a realtor with in-depth knowledge of the boundary for a particular neighborhood and would like to edit Zillow’s boundary. Let’s assume my web map editing skills are limited to editing polygons in Google’s My Maps.

Editing the Neighborhood
I would like to go to a Zillow Web map displaying the neighborhoods (as vector tiles), choose a neighborhood, provide a Google My Maps account URL and click a button that says “edit”. Zillow would then would forward the outline of the selected neighborhood to My Maps account. I would then edit the neighborhood polygon using My Maps editing tools.

Is Google exposing My Maps in their API? When I search the Google Maps API reference for “My Maps” I don’t see anything. It would be great if I could leverage it as an editor.

Updating the Tiles
After editing the neighborhood I would then go back to the original neighborhood at the Zillow site submit the My Maps URL and click “Update”. Zillow would then retrieve the edited polygon, review it, and submit it to a MapCruncher queue. The MapCruncher process would read the queue and update the affected tiles. Maybe they could include a URL to my realty site in exchange for me improving their data. An edit history list could also be maintained.

HPC Cluster for MapCruncher
Granted there would probably not be a lot of updates to this dataset, but if there were, I think the MapCruncher queue would quickly fill up. I wonder if MapCruncher could be deployed to a cluster using Windows HPC Server 2008 cluster. If such a system could be implemented, it seems like, for example, a crowd of appraisal districts could be harnessed to maintain tiled vectors of parcels across an entire state.

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4 comments so far

  1. Pamela Fox on

    My Maps are saved as KML files. You can embed KML files on your map via the GGeoXml function. Enjoy!

  2. Kirk on

    Hi Pamela –

    Thanks! BTW, would you know when the libkml mentioned by High Earth Orbit will be released?
    http://highearthorbit.com/open-source-libkml-coming-from-google/

  3. Darrin Clement on

    Is there a way to ensure topological correctness with kml? I mean, with each polygon being edited by different people, and since changing 1 neighborhood necessarily means changing the adjacent neighborhoods, now will they prevent overlaps, gaps, and even self intersections?

  4. Kirk on

    Hi Darrin –
    Yeah, I think the “review” step I mention above at Zillow would need to check for overlaps. While KML is certainly a good exchange format, especially once it gets canonized into OGC, Zillow should probably store it in a spatial database. When Update button is pushed I think Zillow would pull it into a pending spatial database where topology could be cleaned up. Then once it’s reviewed, loaded onto a production spatial database, where the MapCruncher cluster could see it and refresh the tiles using the latest polygons. Historic polygons would be kept but not shown on tiles to support historic lineage. The production database would also serve out KML to others wishing to edit the latest version or to compare different historic versions of a neigborhood. I think a diff tool could be written for a Mapplet to compare two kml polygons.


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