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Digital Elevation Model

Geometry Type: raster


Table of Contents

         1. Identification
         2. Data Quality and Specifications
         3. Attribute Information

1. Identification

Purpose DEMs may be used as a source for digital orthophotos and as layers in GIS for earth science analysis. DEMs may also be used to assist with volumetric analysis.
Description A bare-earth, hydro-flattened, digital-elevation surface model derived from 2010 Light Detection and Ranging (LiDAR) data. Surface models are raster representations derived by interpolating the LiDAR point data to produce a seamless gridded elevation data set. A Digital Elevation Model (DEM) is a surface model generated from the LiDAR returns that correspond to the ground with all buildings, trees and other above ground features removed. The cell values represent the elevation of the ground relative to sea level. The DEM was generated by interpolating the LiDAR ground points to create a 1 foot resolution seamless surface. Cell values correspond to the ground elevation value (feet) above sea level. A proprietary approach to surface model generation was developed that reduced spurious elevation values in areas where there were no LiDAR returns, primarily beneath buildings and over water. This was combined with a detailed manual QA/QC process, with emphasis on accurate representation of docks and bare-earth within 2000ft of the water bodies surrounding each of the five boroughs.
Source(s) City of New York, University of Vermont Spatial Analysis Laboratory, Sanborn
Publication Dates Data: 08/09/2013
Last Update: 05/27/2013
Metadata: 12/22/2016
Update Frequency: No regular update frequency (DEM update planned for 2017)
Available Formats Zipped raster file
Use Limitations Open Data policies and restrictions apply. See Terms of Use. Access and use of this data set require the approval of the City of New York Department of Environmental Protection. The City of New York and the University of Vermont make no representations of any kind, including but not limited to the warranties of merchantability or fitness for a particular use, nor are any such warranties to be implied with respect to the data.
Access Rights Public
Tags dem, digital elevation model, foot, elevation, gis, doitt

2. Data Quality and Specifications

Horizontal Coordinate System New York State Plane Coordinates, Long Island East Zone, NAD83, US foot
Resolution 1 foot resolution
Spatial Coverage New York City, NY
Temporal Coverage 2010
Positional Accuracy Hunter College conducted an accuracy assessment of the LiDAR point cloud data and determined the vertical RMSE to be 9.5cm. As this data set represents an interpolated surface the vertical accuracy of an individual cell might be much greater. Hunter College determined the horizontal accuracy RMSE for the original LiDAR data to be 33.08cm. As this data set represents an interpolated surface the actual positional accuracy will vary.
Features Captured NA
Features Excluded NA
Capture and Update Notes Vertical datum NAVD1988
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