Hennepin County GIS Division Creates Mobile Assessor Tool
By Zachary Christoff, Principal Information Technology Specialist, Hennepin County GIS Division
The Hennepin County GIS Team was pleased to receive a “2007 Special Achievement in GIS” Award from ESRI. The award was presented at the 2007 ESRI International User Conference in San Diego this past June and recognized the GIS Team for work it conducted on the newly created Hennepin County Assessor’s Mobile Field Card application.
The Hennepin County GIS team developed the Mobile Field Card application to assist the Hennepin County Assessors Department during on-site residential assessments. Previously, assessors edited information using either a paper card or a PDA. They had to print paper maps of the area in which they were working to be able to view information on sales and rate adjustments in the surrounding area. The paper cards required separate data entry, printing and filing. The PDA was slow and displayed only a few fields at a time, making it impossible to do a quick, comprehensive overview of all attributes. Neither method kept a history of updates, so there was uncertainty about the source of changes and no ability to review them or roll them back. Photos were taken with a digital camera and the images had to be manually uploaded and named with the 13-digit property ID number, which was time-consuming and prone to error. Furthermore, there was no way to view the existing photos and sketches in the field without taking along paper copies. Last, there was no way to easily plot or track the completion of revaluations in relation to those that were due to be revalued.
Using the latest technology from ESRI and Microsoft, the GIS Team developed a disconnected (offline) tablet PC application that collects residential assessment attributes, provides interactive mapping capabilities and manages property photos and sketches. The applications framework is composed of:
ESRI’s ArcGIS Server 9.2 Mobile .ADF
Visual Studio 2005 (.NET)
Microsoft SQL Server 2005 CE
While the Hennepin County assessors still have access to an Internet and/or a network connection, they download pre-defined map caches (a collection of pre-rendered map tiles that can be used for display of a map service) before entering the field. While in the field and onsite the assessors have the ability to:
Recall existing GIS data (assessment year, property sales, site adjustments, etc.) on the structure
Edit residential attributes to reflect changes made to the property since the last assessment
Capture and store photographs (using USB cameras)
Review and edit sketches (through linking to third-party software)
All this is accomplished while never needing a ‘live’ internet connection. It is completely distributed and local to the assessor’s own tablet PC. At the end of the day, from any available network connection or wireless hotspot, the assessors can upload and synchronize their data to a temporary holding database pending supervisor approval. The approval process, found as a separate module integrated into the overall application, allows supervisory oversight and record checking prior to the changes being cleared for input into the mainframe database. Completing the synchronization process, all other newly approved assessments are updated back into the field assessor’s tablet PC.
The Mobile Field Card application highlights the many uses of GIS in the field for data capture, manipulation and display. Hennepin County GIS plans in the future to extend the application to other groups and departments within the county for “in the field” data collection.
The Mobile Field Card development team:
Lead developer: Greg Lindberg, Principal IT Specialist (GIS)
Mobile ADF developer: Zach Christoff, Principal IT Specialist (GIS)
Supervisory Review developer: Hart Gilchrist, Senior IT Specialist (GIS)
Database developer: John Gitzen, Senior Systems Software Programmer (Central IT)
Contributing database developer: Warren Fong, Senior IT Specialist (GIS)
Contributing database developer: Jay Meehl, Senior IT Specialist (GIS)