Theme keywords: LiDAR, LAS, Orthophotography
Abstract: This dataset is part of a regularly scheduled update of LiDAR and digital orthotography products. The dataset was created from source imagery acquired by a Trimble TAC80 natural color digital camera and LAS data acquired by a Optech ALTM HA500 (Pegasus) LIDAR sensor from January 18, 2015 to February 5, 2015.
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This dataset is part of a regularly scheduled update of LiDAR and digital orthotography products. The dataset was created from source imagery acquired by a Trimble TAC80 natural color digital camera and LAS data acquired by a Optech ALTM HA500 (Pegasus) LIDAR sensor from January 18, 2015 to February 5, 2015.
TLCGIS regularly uses digital orthophotos and planimetric/hydrographic/topographic data to support regulatory functions, land management and acquisition, planning, engineering and habitat restoration projects.
301 South Monroe Street
Verification of attribute accuracy for LiDAR data involves the use of filtering techniques. Auto-filtering uses algorithms to reclassify data in the point cloud. Hand-filtering involves the analysis of a technician working in a graphic environment to reclassify the erroneous points that may remain in the LiDAR point cloud after auto-filter.
Calibrations of the LiDAR flightline data are performed; this process is known as boresighting. The flightlines are compared to evaluate both their relative and absolute accuracies.
The dataset was reviewed to ensure completeness and accuracy.
Half-foot (0.5') pixel ortho imagery meets a horizontal accuracy (Accuracyr) of 3.8 feet at 95% confidence interval [2.2 feet RMSEr] as specified in the Federal Geographic Data Committee's (FGDC) Geospatial Accuracy Standards, Part 3: National Standard of Spatial Data Accuracy (NSSDA
Horizontal and vertical control was used to establish positions and elevations for reference and correlation purposes and as input to the aerotriangulation process. Control consists of Airborne GPS/IMU and ground control points for ground reference.
TAC80 digital camera
The digital orthophotography was rectified from the digital aerial photography. The orthoimagery was rectified to the DTM data and aerotriangulation results using Cubic Convolution methodology. The ortho imagery was mosaicked and radiometrically balanced to ensure tonal consistency. The final pixel resolution is half-foot (0.50'). Said orthoimagery meets National Map Accuracy Standards.
5970 Greenwood Plaza Blvd
301 South Monroe Street