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:

Recap

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?

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.

Desktop
ArcGIS, ArcView - ESRI, this is the leader in the professional industry.
Geomedia - Intergraph Corp.
MapInfo - MapInfo Corp.
QGIS - open source
GRASS - open source
Server
ArcGIS Server - ESRI
MapServer - open source

GeoSpatial Revolution

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
Tools
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.

Service Functions

Map Services - most basic
Display, query, identify
Data Services
Edit, serve images, sync
Analytical Services
Geocode, route, proximity, buffer
Geoprocessing - custom analysis models

Service Standards

Open GeoSpatial Consortium
Web Map Service (WMS)
Web Feature Service
Web Coverage Service
Other Related Standards
KML (Keyhole Markup Language)
GEORSS
GML (Geography Markup Language)

REST Services

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:

http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_ShadedRelief_World_2D/MapServer/export
?bbox=-183.33, 15.20, -9.53, 74.08
&size=800, 500
&format=jpg
&dpi=96
&f=image

The Mashup

So now we have all these cool new toys lets bring them all together. Using our resources we can create an application using a client side API to represent web services and handle user interaction. There are APIs for Javascript, Flex and Silverlight.

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.

Rate Our Speaker

If you attended the event and have not yet rated our speaker, please head over to SpeakerRate and let Lisa Arnold know you what thought.

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Video

Video of the presentation is available on Vimeo:

Slide Deck

The slide deck is available on SlideShare:

Photos

Photos are available on Flickr:

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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:

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