American Samoa Shoreline Mapping

Woolpert acquired and processed topographic and bathymetric lidar and imagery over Tutuila, Ofu, Olosega, Tau, and Swains Islands as well as Rose Atoll in American Samoa, totaling approximately 277 square miles. This data will be used for the updating of the national shoreline and to support other mapping, charting, geodetic, and coastal uses.

Topographic and Bathymetric Lidar Acquisition and Processing

Woolpert collected lidar in fall 2022 to meet a density of ≥ 2.0 points per square meter (ppsm) and 3-secchi depth in accordance with the QL2B as specified in the National Coastal Mapping Strategy 1.0 document. The topographic lidar data was collected to meet a vertical accuracy of 10 centimeters root mean square error (RMSE). Woolpert deployed a Leica HawkEye 4X (HE4X) topographic/bathymetric lidar system installed in a Cessna 406 aircraft to acquire both topographic/bathymetric lidar and imagery simultaneously using the RCD30 camera included in the CH4X sensor for nearshore and inland waters. Imagery (10 cm) was acquired simultaneously with the lidar data during all flights. Due to the remote nature of the project area and the inaccessibility for ground control survey collection in many areas, a QC flight line was acquired over designated control points established on Tutuila so that all flights were tied into the control network for accuracy. Depths of up to 45 meters were surveyed to laser extinction.

Ground Control

A total of 42 ground survey points were collected in the project area; 12 were used for calibration points, 20 for non-vegetated vertical accuracy (NVA), and 10 for vegetated-vertical accuracy (VVA) check points. The calibration points, NVA, and VVA were dispersed across Tutuila, Ofu, Olosega, and the Tau Islands. The other islands were determined to be inaccessible for ground control survey field work.

Deliverables

Project deliverables included sensor and camera calibration reports, data coverage TIFFs to acquisition coverage review and acceptance, classified LAS point cloud data, topographic/bathymetric seamless lidar, 1-meter Digital Elevation Model (DEM), lidar trajectory files, Total Propagated Uncertainty (TPU) rasters calculated using cBLUE software, normalized intensity rasters, 10-cm ortho-mosaic imagery, product level metadata, alongside acquisition summary, airborne positioning and orientation, and quality assurance reports.