Cook County Ground Imagery Maintenance Project

About this Project

Urban GIS was part of a team responsible for collecting 360 degree imagery of more than 200,000 parcels throughout Cook County. Vehicles equipped with GPS, high resolution cameras and various data collection equipment were used to create images, location points and attributes for Cook County parcels. In addition to the imagery, the project deliverables included address verification and the collection of a variety of critical property attributes.

As a part of the Geospan team, Urban GIS utilized GeoVista technology, which incorporated real-time Six Degrees of Freedom (6-DOF), GPS technology, and an inertial navigational system. These technologies enabled accurate surveying by using oblique and panoramic imagery, collection of latitude, longitude, and elevation in real-time, and vehicle motion correction within .01 degrees. This technology is referred to as “Direct Image Measurement” and allows measurements from calibrated camera imagery without the need for ground control.

The Assessor’s Office was responsible for setting fair and accurate values for 1.8 million parcels of Cook County property. The value of these properties was not determined on an individual basis, but rather by a mass appraisal system. The mass appraisal system was a way to put fairness into the entire assessment process. Imagery collected by Urban GIS assisted the County in developing a computerized sales comparison model. This model was largely dependent on extensive data that was obtained from the field collection that our team performed. The data was heavily utilized in a variety of workflows by the County, partnering municipalities within the County, and the general public at large.