2016 USGS Lidar DEM: Mount Adams, WA

Geographic Extent: Data was collected to cover the Mount Adams survey area. The area covers approximately 563,056 acres in the following counties: Clark, Klickitat, Lewis, Skamania, Yakima

Dataset Description: The Mount Adams 2016 D16 LiDAR project called for the planning, acquisition, processing and derivative products of near-infrared LIDAR data collected at a nominal pulse spacing(NPS) of 0.35 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1.2. The data was developed based on a horizontal datum/projection of NAD83 (HARN) UTM Zone 10N, meters; NAVD88 (Geoid 03), meters. LiDAR derived products include RAW flight lines in swath format, classified and tiled LAS 1.4 files, tiled 1m gridded bare-earth DEM rasters, tiled 1m intensity images, and breaklines used for hydroflattening and bridge removal. Tiled data is made up of 2554 1000m x 1000m tiles named according the US National Grid. At the time of acquisition the area below the aircraft was free of smoke, fog and cloud cover. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, a total of 2054 supplemental ground control points were collected throughout the study area and were used to calibrate and refine the vertical accuracy of the lidar. An additional 239 quality checkpoints, 179 in Bare Earth and Urban landcovers (179 NVA points), and 60 in Tall Grass, Mixed Forest, and Brushland/Low Trees categories (60 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the GeoTIFF files hosted by USGS on Amazon Web Services.

The purpose of these lidar data was to produce high accuracy 3D digital elevation model (DEM) with a 1-meter cell size. Raw lidar point cloud data were used to create classified lidar LAS files, hydro-flattened breaklines, bare earth DEMs, and intensity images.

USGS Contract: G16PC00016 Task Order Number: G16PD00796

CONTRACTOR: Quantum Spatial

Lidar data were acquired and calibrated by Quantum Spatial.

All follow-on processing was completed by the prime contractor.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners.

To the extent possible under law, the U.S. Government has waived all copyright and related or neighboring rights to this dataset.

Data is available online for bulk and custom downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

The specifications require that raw Non-vegetated Vertical Accuracy (NVA) be computed from the both the raw lidar point cloud swath files and the derived DEMs. Additionally, Vegetated Vertical Accuracy (VVA) is also to be computed from the derived DEMS. The NVA was tested with 179 independent check points obtained by QSI located in open terrain, and distributed throughout the project as feasible. These check points were not used in the calibration or post processing of the lidar point cloud data. The VVA was tested with 60 independent check points, also obtained by QSI, located in vegetated terrain and also witheld from the calibration and post processing of the lidar point cloud data. VVA points were also distributed throughout the project area as feasible. Specifications for this project require that the NVA be 19.6 meters or better AccuracyZ at 95% confidence level and that the VVA be 29.4 cm or better AccuracyZ at the 95th percentile.

The 179 independent NVA check points were surveyed using the closed level loop technique. Elevations interpolated from the unclassified lidar surface were compared to the elevation values of the surveyed NVA check points. The RMSE was computed to be 0.035 meters resulting in an AccuracyZ at the 95% confidence level of 0.069 meters.

The 179 NVA check points were also compared to the elevations of the derived bare earth DEMs. The RMSE was computed to be 0.032 meters resulting in an AccuracyZ of 0.063 meters at the 95% confidence level. NVA AccuracyZ has been tested and meets the required 19.6 meter NVA at 95% confidence level using (RMSEz * 1.9600) for both the raw lidar point cloud and derived DEMs, as defined by the National Standards for Spatial Data Accuracy (NSSDA) and herein reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines.

The 60 VVA check points were also surveyed using the closed level loop technique. Elevations for these points were compared to the elevations of the derived bare earth DEMs. The RMSE was computed to be 0.113 meters resulting in an AccuracyZ of 0.209 meters at the 95th percentile. AccuracyZ has been tested on the derived bare earth DEMs and meets the required 29.4 meter VVA using the 95th percentile of the absolute value of all vertical errors in all combined vegetation classes as defined by the National Standards for Spatial Data Accuracy (NSSDA) and herein reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines.

LAS files include all data points collected. No points have been removed or excluded. Shaded relief images have been visually inspected for data errors such as pits, border artifacts, and shifting. LiDAR flight lines have been examined to ensure consistent elevation values across overlapping flight lines. The raw point cloud is of good quality and data passes Vertical Accuracy specifications.

Classified LAS files were tested by QSI for vertical accuracy. All data is seamless from one tile to the next, no gaps or no data areas.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS GeoTIFF files that are hosted on Amazon Web Services (AWS), into the Digital Coast Data Access Viewer (DAV). The DAV accesses the raster data as it resides on AWS.