Overview:
The City of Chicago and surrounding Aviation Boundary chosen for the project, consists of 441.45 square miles and includes some of the highest elevated features found anywhere in the country. The City's goal was to obtain six-inch resolution imagery that would supplement their geospatial database to support change detection, planning and asset management.

Problem:
Historically, the height of the buildings created problems with the quality of data the City needed to achieve their goals. Minimizing building lean and obscured features, as well as leveraging their existing investment in their current mapping data was key to the success of this project. The City opted for higher resolution imagery, selecting 6-inch in lieu of 1-foot as previously done. This, along with the increased radiometry of the direct digital camera, dramatically increased the level of detail visible in the imagery.

Solution:
Pixxures' solution included using a direct digital process that would deliver the level of quality needed within a tight time frame. With its patented ortho-update technology, Pixxures leveraged the City of Chicago and Cook County, Illinois' existing Digital Terrain Model (DTM) data to reduce the overall cost and expedite the turn-around time. The capture of imagery along with ABGPS/IMU and supplemental ground control will support DTM updates where required. The multi-spectral capability of Pixxures' technology offers the City of Chicago the option to take receipt of the near infrared (NIR) band to support environmental needs.

Pixxures designed a specific flight plan that leveraged the advantages of the digital line scanner technology to facilitate a cost savings for Chicago, while providing them with the most advanced data set of the downtown metropolitan area to date. The 12-bit data capture bandwidth increased radiometric depth in the shadows of the tall buildings in the major metropolitan area of interest. Additionally, the nadir configuration of the RGB bands on the focal plate 4, captured a near true ortho perspective of the tall buildings, thus minimizing the angles of incidence in the metropolitan areas. Eighty percent overlap flight plans in the metropolitan area coupled with a LiDAR DTM data set, facilitated correction of building lean and other elevated features such as transportation.

The net result is an extremely accurate high-resolution data set of America's 3rd largest city. Increased resolution and greater image quality, offer more valuable data to the City of Chicago.