What is GIS Day? It’s an annual global event to raise awareness of Geographic Information Systems (GIS) and to demonstrate how technology and geography work together to solve a diverse set of problems such as environmental protection, pollution, health care, land use, natural resources and business efficiency.
About the GIS Mapping Center
Arlington County’s GIS Mapping Center works every day to bring the power of maps and information to constituents and staff members. The Mapping Center not only makes maps, they also:
- Create and maintain the data behind those maps like bike trails,
- Develop applications for staff to collect and edit data such as tree canopy,
- Provide tools like ACMaps for constituents to keep track of changes in their neighborhood, and
- Work with DTS and CPHD on new projects such as open data and the new permitting system.
How We Use GIS Data in WordPress
The Mapping Center uses ArcGIS Server, which exposes a REST API. Our WordPress forms are built with the Gravity Forms plugin. Using the gform_pre_submission hook, we can use the API to do several things with a user-supplied address before the form entry is recorded:
- Standardize (e.g. “2100 N Clarendon Blvd” to “2100 CLARENDON BLVD”) using findAddressCandidates. This is better than a rules-based approach because Arlington’s street naming has a number of quirks.
- Geocode, to facilitate mapping.
- Identify which polygon(s) contain it.
Tips for Developers
- The server uses the Virginia State Plane North coordinate system, not the WGS 84 system you may be familiar with. Specify 4326 as the Output Spatial Reference (
outSR=4326) for WGS 84.
- When requesting JSON output (
f=json), you may provide a callback parameter for JSONP. See Output Formats for more information.
- Your application should handle multiple results with the same score. Some addresses (e.g. 11 Garfield St) exist as both North and South.