NYS ITS GIS Program Office
Geographic Information Systems Clearinghouse
NYC Topobathymetric Data
1-foot resolution topobathymetric digital elevation (DEM) and surface models (DSM), as well as a classified point cloud are available for the areas shown. This project was developed and collected by the New York City Department of Information Technology and Telecommunications (DoITT), Department of Parks and Recreation (Parks), and the Mayor's Office of Recovery and Resiliency (ORR) as part of a federal Disaster Recovery Community Development Block Grant for disaster recovery and resiliency initiatives. DEM datasets were derived from Green and NIR LiDAR data using TIN processing of the ground and bathymetric bottom point returns. Green LiDAR (bathymetric) was used within the water's edge breakline for data splicing shape only (provided as another deliverable) and NIR LiDAR (topographic) was used everywhere outside of this shape. Within the NIR-only portion of the AOI all rivers greater than 20 feet in width and lakes at least 0.25 acres in size have been flattened to consistent elevations. Some smaller streams and ponds were also flattened when deemed appropriate. Water boundary polygons were developed manually and by using automatic algorithms. Elevation values were then assigned to the water's edge from the LiDAR data creating 3D breaklines enforced during model creation to flatten water bodies. Some elevation values inside the NIR-only AOI have been interpolated across areas in the ground model where there is no elevation data (e.g. under dense vegetation). Within the green-only portion of the AOI (inside the low tide breaklines shape), the data has been clipped to avoid triangulation and false interpolation over areas identified as voids in the Bathymetric Coverage Polygon (provided as a separate deliverable). For hydroenforced DEMs, additional hydro-enforcement breaklines were created at all artificial obstructions to flow found in the ground model (i.e. culverts) to break the obstruction of water flow. The horizontal datum for all datasets is NAD83, the vertical datum is NAVD88, Geoid 12B, and the data is projected in New York State Plane - Long Island. Units are in US Survey Feet. Quantum Spatial collected the New York City LiDAR data for The City of New York between 05/03/17 and 07/26/17.