2023 NYS ITS Lidar DEM: Lake Ontario Shoreline, NY

Original Product: These are Digital Elevation Model (DEM) data as part of the required deliverables for the lidar project. Class 2 (Ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM.

Original Geographic Extent: Cayuga, Jefferson, Lewis, Orleans, Oswego, St. Lawrence, and Wayne Counties counties, New York, covering approximately 2337 square miles.

Original Dataset Description: The 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 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification v2023, Rev. A. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID18), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths and as processed Classified LAS 1.4 files, formatted to 2690 individual 1500 m x 1500 m tiles, as tiled Intensity Rasters, and as tiled bare-earth DEMs; all tiled to the same 1500 m x 1500 m schema.

Ground Conditions: Lidar was collected in spring 2023, 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, Sanborn Map Company, Inc., established a total of 28 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 150 independent accuracy checkpoints, 84 in Bare Earth and Urban landcovers (84 NVA points), 66 in Tall Grass and Brushland/Low Trees categories (66 VVA points), were used to assess the vertical accuracy of the data. These check points were not used to calibrate or post process the data.

This dataset was downloaded by the NOAA Office for Coastal Management (OCM) from the New York State GIS Clearinghouse to make the data available for bulk and custom downloads from the NOAA Digital Coast Data Access Viewer.

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 Intensity Images, 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 lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Raster File Type = TIFF

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. The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of the data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

This dataset was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 14cm RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 27 cm at a 95% confidence level.

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

Actual DEM NVA accuracy was found to be RMSEz = 6.3 cm, equating to +/- 12.4 cm at 95% confidence level. Actual DEM VVA accuracy was found to be +/- 11.1 cm at the 95th percentile.

Datasets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the DPA specified for this project.

The NOAA Office for Coastal Management (OCM) downloaded 2690 GeoTIFF files from the New York State GIS Clearinghouse in order to make the data available for bulk and custom downloads from the NOAA Digital Coast Data Access Viewer.