2019 NYS ITS Lidar DEM: Erie, Genesee, Livingston Counties, NY

Product: Calibrated LiDAR version 1.4 .las tiles, classified to bare earth for subsequent derivatives.

Geographic Extent: Erie, Genesee, and Livingston Counties, New York, covering approximately 2,188 square miles.

Dataset Description: Erie, Genesee, and Livingston Counties, New York 2019 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the USGS LIDAR Base Specifications Version 1.3. The data was developed based on a horizontal projection/datum of NAD83(2011), Conus Albers, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 5667 individual 1000 m x 1000 m tiles, as tiled bare earth DEMs; all tiled to the same 1000 m x 1000 m schema.

Ground Conditions: Lidar was collected in the spring 2019, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, New York Office of Information Technology Services provided a total of 44 ground control points that were used to calibrate the lidar to known ground locations established throughout the Erie, Genesee, and Livingston Counties, New York project area. An additional 214 checkpoints, 111 NVA in Bare Earth and Urban landcover and 103 VVA in Tall Grass and Brushland/Low Trees categories were surveyed by Axis Geospatial, LLC to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. 4 of the 111 NVA checkpoints fell beyond the contracted project limits and were not used for the NVA assessment of the DEMs but were used for the NVA assessment of the swaths.

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.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, 3D breaklines, hydro-flattened DEMs as necessary.

Raster File Type = IMG

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 1 Meter

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.

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.

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 Determined DEM Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 5.6 cm RMSE

Vegetated Vertical Accuracy (VVA) = 19.47 cm at the 95th Percentile

Please refer to the USGS Project Report available in the URL section of this metadata record.

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. You may see data voids where caused by areas of low near infrared reflectivity, such as asphalt or composition roofing. We have seen these dropouts on building rooftops throughout this project. Also, there are extreme positive and negative Z values within the LiDAR pointcloud. We have classified these points as Class 7 (Low Point) and/or Class 18 (High Point) to accommodate for these values. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank.

Data covers the entire area specified for this project. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank.

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.