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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.
Geographic Extent: Nassau and Suffolk counties, New York, covering approximately 1627 square miles.
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, Version 2024 rev a. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator Zone 18N, 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 1,873 individual 1500 m x 1500 m tiles, as tiled bare-earth DEMs; all tiled to the same 1500 m x 1500 m schema.
Ground Conditions: Lidar was collected in early 2024, 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 31 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area.
An additional 102 independent accuracy checkpoints, 72 in Bare Earth and Urban landcovers (72 NVA points), 30 in Tall Grass and Brushland/Low Trees categories (30 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.
NYS Elevation Program Page: https://gis.ny.gov/elevation
Last updated 07/01/2026. Please contact NYS ITS Geospatial Services at nysgis@its.ny.gov if you have any questions.
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.
Geographic Extent: Nassau and Suffolk counties, New York, covering approximately 1627 square miles.
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, Version 2024 rev a. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator Zone 18N, 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 1,873 individual 1500 m x 1500 m tiles, as tiled bare-earth DEMs; all tiled to the same 1500 m x 1500 m schema.
Ground Conditions: Lidar was collected in early 2024, 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 31 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area.
An additional 102 independent accuracy checkpoints, 72 in Bare Earth and Urban landcovers (72 NVA points), 30 in Tall Grass and Brushland/Low Trees categories (30 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.
NYS Elevation Program Page: https://gis.ny.gov/elevation
Last updated 07/01/2026. Please contact NYS ITS Geospatial Services at nysgis@its.ny.gov if you have any questions.