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VIRTUAL INTEGRATION OF
WISCONSIN PARCEL DATAHoward Veregin
Brenda HemsteadState Cartographer’s OfficeUW-Madison
Martin GoettlGeography & AnthropologyUW – Eau Claire
A RESEARCH PROJECTResearch focus: virtual data integration
Exploring feasibility of the approach
• Advantages • Limitations• Challenges• Best practices
WHAT WE HAVE DONECombined existing county Web map services into single multi-county online parcel map
Counties supplied REST service endpoints
• No physical data exchange• No edgematching or
common data model• Web map points to
published county dataset (most current data)
WHAT ARE WEB SERVICES?
It depends on who you ask
Technology perspective• Software and standards supporting
computer interaction over the Internet
User perspective• Web apps offering data, product, or
service delivered over Web
WHAT ARE WEB MAP SERVICES?
Technically • Web Map Service = WMS • OGC standard for online maps display• One of a family of standards
Generically• Way to deliver map content over Web• Also, feature and geoprocessing
services…
OUR GOALSProject goals broadened over time
Initial goal: create multi-county parcel Web map
Our focus now is on the research side• Not just parcels, but any theme• Limitations, challenges, best practices• Alignment with other GIS/IT trends
OUTLINE OF PRESENTATION
Background (Howard)
Project status (Brenda)
Main challenges (Howard)• Performance• Availability of map services• Resymbolization and map appearance• Distributed analysis and querying• Legal issues
BACKGROUND
GEOSPATIAL DATA INTEGRATION
“Combining data from different sources to provide a unified view of data for users”
A mashup combines different geospatial themes over one area.
Data integration combines the same theme over different (adjacent) areas.
ADVANTAGE #1“Well-behaved” problem
Once source datasets are delivered, no further external inputs are needed
Relatively easy to allocate personnel and budget to the task
ADVANTAGE #2True integration is possible (in theory)
Rubber sheeting and edgematching eliminate spatial “gaffs” (slivers, overlaps)
Common data model facilitates analysis and querying
ADVANTAGE #3Republishing is relatively easy
Integrator can make data available in a variety of formats
DISADVANTAGE #1Data producers provide copy of dataset
Issues:• Data sharing arrangements• Loss of local control over data• Possible quality decline due to spatial
and/or attribute adjustments
DISADVANTAGE #2Integrated data may not be current
Depends on time it takes to perform integration, plus volatility of the layer
Re-integrating updated data is frequently costly (so often never happens)
DISADVANTAGE #3Curating integrated datasets is increasingly impractical
Large data volumes (“big data”)
More frequent updates, data collection
Need a solution that incorporates distributed
access, visualization, analysis and querying
STATUS
PROCESSSupported and facilitated by LION
Contacted stakeholders (county LIOs) via email
Gathered REST URL (or other URL)
Followed up in person or by phone
Dear <<LIO>>,
This email is to inform you of a joint research project by the State Cartographers Office (SCO) at UW-Madison and the Department of Geography and Anthropology at UW-Eau Claire. The purpose of our project is to investigate the feasibility of using Web map services to create a statewide view of geospatial data collected and maintained at the county level.
Our initial goal is to incorporate existing map services showing tax parcels into a single online map application. We have chosen parcel data for this initial test because this type of data is of interest to a wide range of users. However, our project has a broader purpose, namely to explore how Web map services can be used to support virtual data integration for simple mapping and display. Specific research questions we will be investigating include:
- How much flexibility exists to resymbolize map services from different counties? Can we apply a common set of map symbols to different services to make the integrated map look more consistent?- What are the limitations on querying and analysis, given that data models and attributes are not consistent from county to county? What implications does this have for data standards?- How much of an issue is performance? Are there performance improvements that can be implemented?- Can we integrate commercial and open-source services in a single Web application?
Since our approach makes use of existing Web map services, we do not need to ask for copies of your geospatial datasets. Instead, we will simply be tapping into existing services that are already available on the Web. This also means that any map that includes your county's data will be up-to-date and accurate.
We do have one request. We would greatly appreciate your assistance by providing the URL of your parcel data Web service. For most counties, this will be an ArcGIS Server REST endpoint of the form:
https://<host>/ArcGIS/rest/services
We are also interested in other types of services -- such as ArcIMS, WMS, etc. If you have such a service, we would appreciate your help identifying its URL.
To provide us with your URL, simply reply to this email or to one of the email addresses listed below. So that we can keep on schedule for our project, we would greatly appreciate a response by May 1, 2012.
Please let us know in your email response if you have any conditions or terms associated with accessing your Web services in this way.
We plan to integrate the services into an online map viewer, and then make the viewer available through the SCO Web site (www.sco.wisc.edu) for general access. Users will be able to map and view your county's online parcel data, but will not be able to download the data. The purpose of our project is not to develop a statewide parcel dataset, but rather to explore the feasibility of virtual data integration as a simple way for users to view published Web map services. The end goal of our project is a Web map viewer and a brief report that lists the outcomes of our research questions. We will make this report available on the SCO Web site.
We appreciate any assistance that you can provide. If you have any questions about the project, please contact us. We also plan to attend the WLIA regional meeting in Minocqua in May and will be available to discuss the project there if needed.Sincerely,
Howard Veregin, [email protected], 608-262-6852Brenda Hemstead, [email protected], 608-263-4371Martin Goettl, [email protected], 715-836-4709
REST ENDPOINTS
Representational State Transfer
A communications protocol for the Web
http://example.wi.us/arcgis/rest/services
Once a service is published through ArcMap to ArcGIS Server it is visible at the REST URL
REST SERVICES DIRECTORY EXAMPLE
EXAMPLE
STATUSMost counties use Esri ArcGIS Server (REST)
ArcIMS still widely used (but, migrating)
Small number of counties using Open Source technology
ARCGIS ONLINE
SOME EXAMPLES
Waupaca County
Outagamie County
County Line
REST Services
SOME EXAMPLES
Waupaca County
Outagamie County
County Line
SOME EXAMPLESWashington County Ozaukee
County
Waukesha County
Milwaukee County
Popup
CHALLENGES
PERFORMANCEMany county REST services designed for internal access or occasional citizen use
Impact on these users if site usage increased significantly?
One of the reasons we are not releasing a public-access viewer at this time
SERVICE AVAILABILITYServices can be added, removed, or modified
Affects where the map viewer points to the data
Services may also go off-line
Virtually no control over these changes
SERVICE AVAILABILITY
Map service not responding
SERVICE AVAILABILITY
Map service unavailable
RESYMBOLIZATIONNeed to control symbol color and size
Also need to control zoom levels where features appear and disappear
Relatively easy to do, but little consistency or standardization between counties
DISTRIBUTED QUERYING
How to query across multiple datasets with different schemas
A big research issue (“semantic web”)
“Distributed query” or “federated search”
user query subqueries to participating data sources aggregation of query results
LEGAL ISSUESOpens up new legal issues
Data readily incorporated into any mashup for any purpose
Loss of control over data
How will local governmentsreact to this new technology?
CONCLUSION
WHO BENEFITS FROM INTEGRATED DATA?
Geospatial professionals• Demonstrate ROI for cost of geospatial services• Model a successful data integration scenario
Counties• Active participants in an effort that will have
impacts beyond county boundaries
Citizens and taxpayers• Maximizing utilization of taxpayer investments• Obtaining greater benefits • More effective and efficient governance!
BENEFITS OF STUDYEducation about GIS Web services
Forward-looking way of thinking about data integration
Challenges and solutions to this new approach
Standards and best practices for Web services
THANK YOU!Howard Veregin, [email protected]
Brenda Hemstead, [email protected] Goettl, [email protected]
Photos by UW-Madison, University CommunicationsGeology Lab Michael Forster Rothbart/University of Wisconsin-Madison/2003Globe Jeff Miller/University of Wisconsin-Madison/2011Community Engagement Jeff Miller/University of Wisconsin-Madison/2009Jeopardy Bryce Richter/University of Wisconsin-Madison/2008All photos © Board of Regents of the University of Wisconsin System
Other photosVIIRS Suomi Earth Image Norman Kuring/NASA/NOAA/GSFC/Suomi NPP/VIIRS
