2019 USGS Lidar DEM: Eldorado, CA

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Bulk download of data files in GeoTIFF format, based on a horizontal datum/projection of CA State Plane Zone 2 NAD83(2011) US Survey Feet (EPSG: 6418), and a vertical datum of NAVD88 (GEOID12B) in US Survey feet (EPSG: 6360).

Link to the additional information available for this data set from the USGS. This information includes reports, tile index shapefiles, and hydro breaklines.

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

This graphic displays the footprint for this lidar data set.

Link to the USGS report that provides the project information, vertical accuracy results, list of classifications, sensor used, and work unit information.

Link to the lidar report.

Link to the survey report.

Aerial LiDAR Acquisition: LiDAR acquisition was done using Carson City Airport (KCXP),Placerville Airport(JS4761),Tracy Municipal Airport (KTCY) and Columbia Airport(O22). DAS used two dedicated GPS base station located at the respective airports to support the aerial LiDAR acquisition. DAS used Leica’s Terrian Mapper LiDAR Sensor (SN90524) for the acquisition. The project consisted of 399 flightlines totaling 8,871.32 nautical miles. The acquisition was completed in 22 lifts on October 21st - November 2nd,2019 and March 5th, 2020.

Ground Control Survey: A survey was performed to support the acquisition of Light Detection and Ranging (LiDAR). The control network involved a total of One Hundred Sixty-Three (163) check points (94 NVA + 69 VVA). The points were a combination of the following ground cover classification: Open Terrain, Urban Terrain, Bare Earth, High Grass, and Low Trees. All field survey observations were conducted between October 22, 2019 and it was completed October 30, 2019 with Leica GPS GS15 and 1200 equipment.

LiDAR Data Processing: Inertial Explorer 8.9 software was used to compute inertial solution file (*.sol) for each mission using ground GPS base station. The resulting solution was checked to ensure a minimum accuracy of +/- 0.05m, combined separation, for horizontal and vertical positions. Inertial Explorer methodology integrates Inertial Navigation Solution by processing the GPS data and Inertial Measurement Unit (IMU). The software applies the reference lever arms for the GPS and IMU during the process to determine the trajectory (position and orientation) of the LiDAR sensor during the acquisition mission. Inertial Explorer generated graphical results was reviewed to ensure that the IMU data was healthy. These results are found in Appendix D.

Raw LiDAR sensor ranging data and the final solution sensor trajectory (*.sol), from Inertial Explorer, were processed in Leica’s HxMap software to produce LiDAR point cloud swath for each flight line in LAS version 1.4 file format. Quality control of the swath point cloud was performed to validate proper functioning of the sensor system, full coverage of the project area and point density of the LiDAR data. Swath point clouds were assigned unique file source identification. The data was found to be complete and consistent with the sensor calibration parameters.

LiDAR Calibration: HxMap is the common workflow platform for Leica airborne sensors. The processing workflow involves; Ingest, Block Creation, LiDAR Matching, Quality Assurance (QA) and Product Generation.

LiDAR is processed in HxMap by generating point clouds from raw sensor data during the Ingest step. Noise filtering, sensor installation calibration and atmospheric condition parameters are also applied during the ingest process. Once all data is processed through ingest, they are assembled into a block for LiDAR Matching. The LiDAR Matching step resolves LiDAR registration errors which remain in the point clouds after sensor and installation calibration parameters are applied in the ingest step. QA tool is run on the Block after LiDAR Matching to verify quality of results. QA results are reviewed to ensure that, 95% of patches less thand 5cm for Vertical Scan Direction and Vertical Line Separation. Ground control points are also included to assess absolute accuracy for the point cloud data. LiDAR products are finally generated in the Product Generation step as LAS swaths (LAS 1.4). Vertical (Z) shift (calculated from QA step) is also applied during the product generation.

Bare-Earth DEM Creation: Bare-Earth Digital Elevation Models (DEMs) were derived using the hydro break line and bare-earth (ground) LiDAR points, all DEMs were created with a grid spacing of 1.0 Feet. The DEMs were cut to tiles of 2,500 feet X 2,500 feet index, provided by the US Geological Survey.

The NOAA Office for Coastal Management (OCM) created references to the USGS GeoTIFF files that were ingested into the NOAA Digital Coast Data Access Viewer (DAV). No changes were made to the data. The DAV will access the raster data as it resides on Amazon Web Services (AWS).

These are the GeoTIFF files that are being accessed:

https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/OPR/Projects/CA_UpperSouthAmerican_Eldorado_2019_B19/CA_UpperSouthAmerican_Eldorado_2019/TIFF/