2019 3DEP WA DNR Lidar DEM: Springdale and North Spokane County, WA

Original Product: Hydroflattened Digital Elevation Model (DEM) data covering the Washington DNR 3DEP Processing project area.

Geographic Extent of Original Data: This dataset and derived products encompass an area covering approximately 562,137 acres of Eastern Washington.

Original Dataset Description: The Washington DNR 3DEP Processing Lidar project called for the planning, acquisition, and processing of lidar data collected to Quality Level 1 (QL1) standards. Project specifications are based on the U.S. Geological Survey National Geospatial Program LIDAR Base Specification, Version 2.1. The data was developed based on the NAD83 2011 horizontal datum and the NAVD88 Geoid 18 vertical datum. Data was projected in Washington State Plane North, U.S. feet. Lidar data was delivered as calibrated and classified LAS 1.4 files. Lidar flight line swaths were processed to create 1,097 classified LAS 1.4 files delineated in 5,000ft x 5,000ft tiles. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create 1,097 2.0 foot hydro-flattened Raster DEMs delineated in 5,000ft x 5,000ft tiles. Non-Vegetated Vertical Accuracy (NVA) was assessed using 64 check points located on bare earth in clear, unobstructed areas. Vegetated Vertical Accuracy (VVA) was assessed using 43 check points in Tall Grass, Forest, and Shrub landcover types. Additional products include classified LAS files, intensity images, highest hit surface models, and 3D breaklines of rivers and lakes within the study area.

Ground Condition of Original Data: Ground condition was free of snow and acquisition occurred free of smoke, fog and cloud cover.

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 USGS 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 3D Elevation Program and the Washington DNR 3DEP Processing contract. The lidar point cloud data were used to create classified lidar LAS files, intensity images, hydro-flattened DEMs, highest hit DSMs, and 3D breaklines of rivers and lakes within the study area.

Raster File Type = TIFF Bit Depth/Pixel Type = 32-bit float Raster Cell Size = 2.0 foot Interpolation or Resampling 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.

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.

LiDAR Mapping Suite 2.4, Applanix PosPac 7.1, Microstation CONNECT version 19, TerraScan Version 20, TerraModeler Version 20, TerraMatch Version 20, ESRI ArcGIS 10.3, Windows 10 Operating System

Lidar horizontal accuracy is a function of Global Navigation Satellite System (GNSS) derived positional error, flying altitude, and INS derived attitude error. The obtained RMSEr value is multiplied by a conversion factor of 1.7308 to yield the horizontal component of the National Standards for Spatial Data Accuracy (NSSDA) reporting standard where a theoretical point will fall within the obtained radius 95 percent of the time. Based on a flying altitude of 1,830 meters, an IMU error of 0.003 decimal degrees, and a GNSS positional error of 0.015 meters, the Washington DNR 3DEP Processing site was compiled to meet 0.98 feet (0.30 meters) horizontal accuracy at the 95% confidence level or 0.17 m RMSEr.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class. Specifications for this project require that the NVA be 0.196 meters or better AccuracyZ at 95% confidence level. Vegetated Vertical Accuracy (VVA) is also to be computed. Specifications for this project require that the VVA be 0.300 meters or better AccuracyZ at the 95th percentile.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class.

USGS DEM Determined Vertical Accuracy:

Tested NVA RMSEz = 2.3 cm

Tested 95th percentile value for VVA is : 15.54 cm

For more information see the USGS project report and the lidar report. The links to these reports are provided in the URL section of this metadata record.

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.

DEM files were tested by NV5 Geospatial for vertical accuracy. All data is seamless from one tile to the next, no gaps or no data areas.

Data is backed up to cloud storage.

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 under the usgs-lidar-public-container.