Recap: Web Mapping & The Power of Where
March 19, 2011 Zerek Welz
For our March 2 event, Lisa Arnold discussed how to translate geographic information onto the web. If you were unable to attend or need a refresher, we've got you covered:
Howdy web friends! It's March and that means Lisa Arnold came to talk to everyone about GIS, Geographic Info Science. Lisa showed us how to take geo oriented data and put it on a map for interactivity and research.
GIS is a computer based tech to collect, integrate, analyze, query, model and vizualize geo oriented data (like a visual database). You can track things like wetlands, soils, rocks, elevation, political boundaries and prairie dogs. Everything coordinates with a specific point on the earths surface. All of this data can be flipped in or out of the map like layers in a Photoshop file.
What can we use all this for?
- Location - What is it at? What exists at a particular location?
- Condition - Where is it? Find location where certain conditions are met.
- Trends - What has changed since 2 months ago? 2 years ago? Track the differences in the area over time.
- Patterns - Do any spatial patterns exist? What spatial relationships exist between the geo data?
- Modeling - Predict cause and effects of new scenarios from past data
OK, cool. How do we use it?
Glad you asked. Lisa just happens to know and she gave us a handy dandy list. I won't list them all, but you can grab them from the slides if you need some extras.
- ArcGIS, ArcView - ESRI, this is the leader in the professional industry.
- Geomedia - Intergraph Corp.
- MapInfo - MapInfo Corp.
- QGIS - open source
- GRASS - open source
- ArcGIS Server - ESRI
- MapServer - open source
The Geospatial Revolution Project is an integrated public service media and outreach initiative about the world of digital mapping and how it is changing the way we think, behave, and interact. Using GIS they helped to solve problems with obesity in neighborhoods where no grocery stores had been built nearby. You can view the website at http://geospatialrevolution.psu.edu/.
Web GIS Models
- The Head
- Consumer web GIS applications
- Limited but commonly used functions
- Large user bases
- Emphasis on usability
- Advertising business models
- The Long Tail
- Professional web GIS applications
- A wide array of functions
- Many small user bases leading to a large user base
- Emphasis on functionality
- Organizations acquire software and then configure or customize for specific needs which may or may not be free to end users.
Web GIS Architecture
The GIS application architecture consists of 3 main parts. The GIS database, the GIS server and a Web Server. A client can make a request to the web server which calls back to the GIS server. The GIS server uses the GIS database to construct the data. This data is then returned through the web server to the client. The slides have a prettier not so wordy example of the above.
GIS Application Components
- Basemap - often caches services pre-created by server.
- Road maps
- Aerial imagery
- Operational Layers - dynamic data rendered by the browser.
- Real time weather
- Disease locations
- Find an address
- Get directions
- Query or search
Geospatial Web Services
GIS application components are driven by geospatial web services. The web service is a method of communication. The programming interface can be accessed by other applications. There is a really nice slide that goes into a lot more detail for this one.
- Map Services - most basic
- Display, query, identify
- Data Services
- Edit, serve images, sync
- Analytical Services
- Geocode, route, proximity, buffer
- Geoprocessing - custom analysis models
- Open GeoSpatial Consortium
- Web Map Service (WMS)
- Web Feature Service
- Web Coverage Service
- Other Related Standards
- KML (Keyhole Markup Language)
- GML (Geography Markup Language)
The communication between the web server and a client is RESTful allowing URLs to access information from GIS servers. Using the ArcGIS Server REST API to generate a 800 x 500 JPG map covering the United States would look like the following:
?bbox=-183.33, 15.20, -9.53, 74.08
ArcGIS Viewer for Flex can be pointed to a RESTful URL and be used to create a basic application in just a few minutes. Lisa demonstrated this by pulling in some prairie dog info and over a map with prairie dog sightings and population numbers. With this you get all the things you expect from a map: scrolling, zooming, geographic data and roads.
The application uses XML to pass and display info. Data from the application can be exported in GDB formats and more.
Start using it now!
Now don't mind me, but I have a prairie dog dating site to go create.
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Video of the presentation is available on Vimeo:
The slide deck is available on SlideShare:
Photos are available on Flickr:
Thanks to All Our Volunteers!
Webuquerque just wouldn't be the same without helping hands from our community members:
- Photos: Virginia DeBolt
- Live Tweets: Brooks Walch
- Equipment Breakdown: Andrew Collins
- Recap: Zerek Welz
Want to help? Let us know if you'd like to lend a hand. Interested in speaking? Let us know that too!
Stay Tuned for Our Next Event!
For our April 6 event, Brian Arnold will discuss why you should use Git, how to do so, and how you can use it to share your work with others via Github:
- Version Control
Let Us Know What You Think
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