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status update

2010-11-24 16:26:18.492345+00 by Dan Lyke 8 comments

playing with Sonoma County GIS data. Does this give Petaluma people any ideas? http://www.petalumaopen.com/en/Using_GIS_Data

comments in descending chronological order (reverse):

#Comment Re: made: 2010-11-27 12:33:24.412248+00 by: jeff

> I like to say GIS really adds "Where" to SQL

That's funny and undoubtedly true, Eric! :)

#Comment Re: made: 2010-11-27 02:42:49.741919+00 by: ebradway

The zip file has areas as well as lines and events. It should be best available for your area. If you need better, you'll want to start tracing lines in OSM.

I like to say GIS really adds "Where" to SQL.

#Comment Re: made: 2010-11-25 16:15:32.298491+00 by: Dan Lyke

Eric, thanks, I'll take a look at that ZIP file you sent. The USGS hydrology data I got from the county was pretty sparse, and line only.

Mapnik has a server mode that I should be able to point OpenLayers at, but I've also got QuantumGIS for just exploring the data.

Jeff, there are all sorts of distance and intersection and expand modifiers in PostGIS. It even adds spatial indexes for faster searching to PostgreSQL. It's full-on SQL that knows about a couple of geometry types, polygons, lines, points, and so on, and map projections.

#Comment Re: made: 2010-11-25 14:52:16.434727+00 by: jeff

Dan--I love your last SQL query example in your link above.

What other interesting attributes can be added to the where clause?

#Comment Re: made: 2010-11-25 05:17:23.752524+00 by: ebradway

FYI: You can use GeoServer to provide a WFS vector data source for OpenLayers. That should be more dynamic than Mapnik. GeoServer is a Java Servlet but it can also run stand-alone. It's probably one of the best pieces of Java-developed software I've used.

#Comment Re: made: 2010-11-25 05:00:22.1736+00 by: ebradway [edit history]

It's a little obtuse the first time you do it, but you can download current NHD from The National Map. Peta luma is in Subbasin 18050002.

To actually download the data:

  1. Turn on the "GIS Toolbox" in the upper left corner
  2. Open the "USGS" Tab in the tool box
  3. Click the button on the far left - the arrow pointing down - it's "Download"
  4. For the dropdown box "Choose a reference area", select "NHD Subbasins"
  5. Click on the map in the general area of Petaluma
  6. Click on the Green "A" push pin icon on the left-hand side of the window
  7. Click on "See available data" on the window open on the map.
  8. From here you can actually select "Hydrography". Be sure to specify "Shapefile" for the format. The others you can't read without Esri ArcGIS

    The rest is too painful to recount, but it's like buying something from a terribly designed online store. Eventually, you'll get to "checkout" and be issued a ticket number. Sometime later in the hour, day or week, you'll get an email with a link to the data.

    Yes, this is the paragon of user centered designed. Yes, the research project I work on is titled "User Centered Design for The National Map". No, I do not have any input on how this process was setup. The current "viewer" and download process is the result of Bush's Circular A-76 which forced the National Geospatial Program to bid competitively against private companies to continue the role it served since John Wesley Powell stared the Topographic Mapping program in the late 1800s. NGP kept the "contract" but everyone with any marketability left for greener pastures. So we have a viewer that meets some requirements, was very cheap (it was actually developed for NGA as a the Palanterra viewer). And, despite the fact that the USGS as a whole got a decent budget increase for FY2011, NGP had it's budget cut.

    [sarcasm]But, as you know, mapping and geospatial stuff just isn't relevant in today's world.[/sarcasm]

    #Comment Re: made: 2010-11-24 21:52:53.352427+00 by: Dan Lyke

    And using QGIS (rather than going all the way through to rolling my own viewer using Mapnik and OpenLayers) I can see that, indeed, the streams disappear through downtown.

    #Comment Re: made: 2010-11-24 20:27:34.200172+00 by: Dan Lyke

    This should be all parcels within 50 meters of a USGS stream. Interesting gap in there downtown, but I haven't figured out the tools to look at the USGS stream data more closely yet.