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2008 City of Baltimore Lidar
browse graphic In the spring of 2008, the City of Baltimore expressed an interest to upgrade the City GIS Database with mapping quality airborne LiDAR data. The City of Baltimore currently had in place a contract for mapping GIS/services with the KCI/Sanborn Joint Venture Partnership, L.L.C. under Project 1051. The City of Baltimore issued Change Order #1 on on Project 1051 for the LiDAR acquisition and processing. KCI/Sanborn acquired the LiDAR data over the City of Baltimore (approximately 90 square miles) during one long mission on 15 April 2008. A Leica Airborne Airborne Laser Scanner Model ALS 50 was used in a Sanborn Aero Commander 500B (Registration N6172X) to acquire the data. The airborne mission was flown 15 April 2008. The LiDAR system acquired calibration data the same day by conducting flight passes over a known ground surface before and the LiDAR mission. During final data processing, the calibration parameters were used in the final post-processing software. The acquired LiDAR data were processed to obtain the following deliverables: -DEMs of first and last returns and bare earth (all point data) -LAS format data in a tile grid provided by the City/KCI -Gridded DEM in ESRI format (Arc Binary Grid -Arc/INFO Lattice ) produced from Bare Earth Mass Points in 1-meter resolution (Grid size) -Associated FGDC compliant metadata in XML format The project specifications called for the LiDAR survey to comply with industry standard FEMA guidelines for accuracy. The FEMA requirement for this type of mapping calls for vertical errors not to exceed 0.185 meter (0.61 feet) RMSE when compared with ground check points over open flat terrain and 0.370 meter (1.22 feet) for other types of terrain. This accuracy requirement was comfortably met with comparing LiDAR derived elevations against 50 ground control check points provided by KCI Technologies. These control points were photo control points used as part of the photogrammetric mapping project and independent LiDAR checkpoints surveyed by KCI and Mercado after the data was delivered. The RMSE error observed was 0.058 meter (0.189 feet) over all 50 check points.