Feature Loudoun County, Virginia, has a mature enterprise GIS implementation. The county recently developed an application that integrates computer-assisted mass appraisal (CAMA) with GIS to improve the workflow of the county Assessor's Office. With this application, county appraisers can easily search, map, and analyze assessment data. Loudoun County, Virginia, part of the Washington, D.C., metropolitan region, has experienced rapid growth since the mid-1990s. In 2008, the county had an estimated 98,000 households. Real property assessments have declined approximately 9 percent in the last two years, mirroring national trends in real estate values. The county was an early adopter of GIS and has used Esri products since 1986, developing processes to map property boundaries and assign addresses. Its GIS currently has more than 150 data layers and supports a wide range of internal users through ArcGIS Desktop products and intranet applications as well as hosting an Internet mapping site. ArcGIS Desktop is served through Citrix application servers while the database is managed using ArcSDE running on an IBM AIX server with DB2 as the underlying relational database. Since DB2 is the county mainframe standard, spatial data can be used in a variety of ways in conjunction with other county databases and systems including computer-aided dispatch (CAD) and permitting. Past GIS Use: A Laborious Manual Process The CAMA system used in Loudoun County is a mainframe system designed in the 1980s. It lacks functionality and requires a great deal of knowledge and expertise to manipulate the data from the CAMA system and link it to the GIS parcel layer. The Assessor's Office does not have dedicated mapping staff, so staff appraisers must work with the GIS staff to map any detailed assessment data. Appraisers download assessment data to spreadsheets that are given to the GIS staff. These spreadsheets are joined to tables in the county's GIS so assessment data can be mapped. This time-consuming process was required even when an appraiser simply needed to review data and didn't need a printed map. Alternatively, appraisers could view data using WebLogis (www.loudoun.gov), the public mapping program created by the GIS staff using ArcIMS to view GIS data. Appraisers must view their data in a separate window and the program does not include data needed by the appraisers, such as values, structure type, sales, improvement square footage, and year built. Appraisers must first use the parcel identification number (PIN) search to locate the parcel. Once the parcel is found, clicking the See Assessment button sions can perform analyses on this data. Loudoun County's spatial data includes land records data (e.g., parcels, addresses, and centerlines) maintained daily in the geodatabase. Assessor's data on residential and commercial properties is maintained regularly as tables in the CAMA system. An external DB2 database called Parcel Database System (PDBS) contains the weekly upload of CAMA data that is maintained by Loudoun County's Department of Information Technology for data distribu- Loudoun County Assessor's GIS main tool screen shows parcel ownership, structure information, recent sales, and tax history information for that parcel from the Real Estate Tax, Assessment & Parcel Database. The process must be repeated to view information on each parcel and is extremely time consuming. Present GIS Use To remedy this situation, Loudoun County created an easy-to-use application for the Assessor's Office that allows appraisers to map and query assessment data. The first version of this application was completed in September 2008. Since that time, five additional versions have been released. Initially it was used for querying and mapping assessment data, but later vertion purposes. After identifying the information needed for the mapping application, an extract of PDBS tables containing the required fields is maintained in the GIS ArcSDE database and updated weekly. DB2 stored procedures are also used to instantly access the external PDBS database for creating callouts in the application or returning pertinent data by clicking on a map location. The application provides access to specific GIS data layers and labels those layers with associated data (i.e., PINs and street names). To make the map more readable, the parcels are symbolized by shading them using the assessor's neighborhood codes. Users can toggle between different classifications for other analyses. To Continued on page 24 www.esri.com ArcUser Winter 2010 23