Posted by: socalgis | July 20, 2011

Regional Task Force on the Homeless uses Data Driven Pages to Collect GIS Data about San Diego County’s Homeless Population

We were elated to see one of our clients, the San Diego-based Regional Task Force on the Homeless (RTF), present at the TechSoup/Esri NGO Showcase during the 2011 Esri User Conference. This session included a series of interesting stories on how GIS is being used to empower citizens while improving advocacy and efficiency to help build a better society. The RTF is a non-profit organization that strives to obtain accurate data regarding the populations of homeless persons in San Diego County.

The RTF coordinates an annual survey, called the Point-in-Time Count (PITC), in which they enlist and organize the help of countless volunteers who hit the streets to locate homeless individuals across San Diego County. This event occurs on one very early January morning. As you can imagine this is an enormous effort. The data collected offers a snapshot of the homeless population that will inform policy-makers and organizations at all levels.

Through GIS, RTF is able to locate homeless populations as they relate to Cities, Assembly Districts, Ambulance Response Areas or any other relevant geospatial layer. GIS provides an effective way to compare year-over-year changes in the homeless populations as infrastructure is built and the economy changes. GIS complements the RTC’s traditional efforts as the local manager of the Homeless Information System (HMIS) which provides support for numerous local service providers. They bring value by leveraging both GIS and the HMIS program to provide a clearer picture of services homeless populations use and identify opportunities to bring needed support.

One of the key goals of our training with the RTF was to empower them to create the maps used by volunteers in the PITC. Data Driven Pages is new functionality offered with ESRI’s ArcGIS 10 Desktop software; employing Data Driven Pages functionality allows for the generation of a series of organized map pages through one map file. It also ensures the pages are consistent in terms of data content as well as layout and GIS data shown. The pages can then be printed individually or as a group without having to open and close multiple files. Exporting the pages to PDF, or other formats, works the same way. Changes made to the map will reverberate throughout all of the pages. This technique is an easy way to quickly and efficiently produce multiple maps using the same layout and data. Additionally, all the maps will be produced and saved in one ESRI map file. This saves time and computer resources.

The way Data Driven Pages work is simple: the user creates an index file which determines the extent of every map to be created. The tool offers flexibility as to how this file is created but basically there are 2 options: creation of a uniform grid, or using existing GIS data. If you choose to use existing GIS data, the map extents are based upon each feature in the file used. Point, line, and polygon feature classes are all allowed.

Link to ArcGIS Desktop Help for Data Driven Pages

Link to learn about or volunteer for the Regional Task Force for the Homeless Point-in-Time Count


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