2017 - 2018 USGS QL1 Lidar DEM: WA 3 County

Product: These are Digital Elevation Model (DEM) data for QL1 portion of the WA 3 County LiDAR 2017 lidar project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 3 foot hydro-flattened Raster DEM.

Geographic Extent: This dataset and derived products encompass an area covering approximately 1513 square miles. The area includes Columbia, Garfield, and Walla Walla counties in south eastern Washington.

Dataset Description: RAW flight line swaths were processed to create classified LAS 1.4 files delineated in 3000 ft x 3000 ft tiles. Each LAS file contains LiDAR point information, which has been calibrated, controlled, and classified. Additional derived products include intensity images, highest hit surface models, and 3D breaklines of rivers and lakes within the study area. Ground Control Points were acquired and calibrated by Quantum Spatial, Inc. Data acquisition was coordinated by Quantum Spatial and all lidar data calibration, and follow-on processing were completed by Quantum Spatial, Inc.

Ground Conditions: Acquisition below aircraft free of smoke, fog and cloud cover. A small area with remaining snow on the ground was noticed in the data. The difference was only noticed due to the area being acquired at two different times. The high snow level was classified to class 21 and the overlapping mission acquired without snow on the ground was used for ground model creation. A shape of this area has been provided.

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 the lidar data was to produce a high accuracy 3D dataset that meets all necessary standards laid out by the 3DEP initiative. The raw lidar point cloud data were used to create classified lidar LAS files, intensity images, hydro-flattened DEMs, highest hit surface models, and 3D breaklines of rivers and lakes within the study area.

Raster File Type = GRID

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 3 Feet

Interpolation or Re-sampling Technique = Triangulated Irregular Network

Required Vertical Accuracy = 19.6 cm NVA

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, the Vegetated Vertical Accuracy (VVA) is computed from the derived DEMs. The NVA was tested with 85 independent check points located in open terrain, and distributed throughout the project as feasible, while VVA was tested with 79 independent check points located in a variety of vegetation classes distributed throughout the project area. These check points were not used in the calibration or post processing of the lidar point cloud data. Specifications for this project require that the NVA be 19.6 cm meters or better AccuracyZ at 95% confidence level and that the VVA be 29.4 cm or better AccuracyZ at the 95th percentile.

Tested 0.083 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud files was calculated against TINs derived from the final calibrated and controlled data using 85 independent checkpoints located in Bare Earth and Urban land cover classes.

Tested 0.077 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the classified lidar point cloud files was calculated against rasters derived from the final calibrated, controlled, and classified data using 85 independent checkpoints located in Bare Earth and Urban land cover classes.

Tested 0.206 meters VVA at the 95th percentile as defined by the National Standards for Spatial Data Accuracy (NSSDA). The VVA of the classified lidar point cloud files was calculated against rasters derived from the final calibrated, controlled, and classified data using 85 independent checkpoints located in forest, shrub, and tall grass land cover classes.

These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the entire area specified for this project.

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.