August 18, 2015 -- Under its Geospatial Products and Services Contract (GPSC) with the U.S. Geological Survey (USGS), Dewberry is executing a task order to evaluate two new forms of light detection and ranging (lidar) to determine if single photon lidar (SPL) and Geiger mode lidar (GML) can satisfy USGS Lidar Base Specification version 1.2 for quality level (QL2) lidar with two points per square meter (pts/m2) and vertical RMSE ≤10 cm for use in the USGS 3D Elevation Program (3DEP).
Using approximately 500 square miles of existing QL2 lidar data from traditional linear mode lidar (LML) and quality control checkpoints in northern Connecticut, Dewberry will determine the capabilities and limitations of SPL and GML, acquired both day and night during leaf-on conditions, to deliver QL2 lidar or better for the 3DEP. Dewberry will evaluate both absolute and relative horizontal and vertical positional accuracies compared with the USGS V1.2 specification, as well as noise levels from sun light, for example, data smoothness and repeatability, data spatial distribution and density, and other parameters as needed.
Dewberry will determine if higher-density quality level (QL1) lidar (≥8 pts/m2) can be obtained from SPL and GML and if different flying altitudes are required to achieve foliage penetration suitable for QL2 or QL1 lidar during leaf-on conditions. The task will help to determine if these technologies could be used to acquire QL2 or QL1 data year-round.
Dewberry will also help conclude if changes would be required to the USGS Lidar Base Specification V1.2 to accommodate these new lidar technologies and help USGS determine if SPL and GML can be used for future GPSC lidar task orders, as well as traditional LML. Dewberry will also evaluate the effectiveness of existing commercial LML processing and cleaning software packages in processing, filtering, and classifying point cloud from both the SPL and GML.
About Dewberry’s Geospatial Services
Dewberry has continuously served as a USGS contractor since 1998. Dewberry specializes in digital elevation data, having edited the textbook Digital Elevation Model Technologies and Applications: The DEM Users Manual, published in 2001 and 2007 by the American Society for Photogrammetry and Remote Sensing (ASPRS), with chapters on lidar, accuracy standards, and quality assessment. For USGS in 2012, Dewberry authored the National Enhanced Elevation Assessment (NEEA), which provided the blueprint for the 3DEP and forecast the future use of topographic lidar technology trends such as SPL and GML.