New York State Digital Elevation Models

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: Unknown

Publication_Time: Unknown

Title: New York State Digital Elevation Models

Publication_Information:

Publication_Place: Reston, VA

Publisher: U.S. Geological Survey

Online_Linkage: <http://gis.mannlib.cornell.edu/all_dem.html>

Description:

Abstract:

A digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A-record), followed by a series of profile records (B-records) each of which include a short B-record header followed by a series of ASCII integer elevations per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (10- by 10-m data spacing) is cast on the Universal Transverse Mercator (UTM) projection (the quads UTM zone can be found in the header record(Record A)) in the North American Datum of 1927. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle, but overedges are published as separate DEM files. Coverage is available for all quads completely contained within New York State, plus some additional ones falling along the borders and containing significant area of the State's land.

Purpose:

DEMs can be used as source data for digital orthophotos and as layers in geographic information systems for earth science analysis. DEMs can also serve as tools for volumetric analysis, for site location of towers, or for drainage basin delineation. These data are collected as part of the National Mapping Program.

Supplemental_Information:

7.5-minute DEMs have rows and columns which vary in length and are staggered. The UTM bounding coordinates form a quadrilateral (no two sides are parallel to each other), rather than a rectangle. The user will need to pad out the uneven rows and columns with blanks or flagged data values, if a rectangle is required for the user's application. Some software vendors have incorporated this function into their software for input of standard formatted USGS DEMs.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: Unknown

Currentness_Reference: Ground Condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: Irregular

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -074.235500

East_Bounding_Coordinate: -073.702900

North_Bounding_Coordinate: +42.815300

South_Bounding_Coordinate: +42.421500

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: DEM

Theme_Keyword: digital elevation model

Theme_Keyword: digital terrain model

Theme_Keyword: hypsography

Theme_Keyword: altitude

Theme_Keyword: height

Theme_Keyword: contour line

Theme_Keyword: digital contours

Theme_Keyword: landforms

Theme_Keyword: relief

Theme_Keyword: topography

Theme_Keyword: cartography

Theme_Keyword: digital mapping

Theme_Keyword: hydrography

Theme_Keyword: mapping

Theme_Keyword: raster

Theme_Keyword: grid

Theme_Keyword: cell

Theme_Keyword: NYSDEC

Place:

Place_Keyword_Thesaurus:

Department of Commerce, 1987, Codes for the Identification of the States, The District of Columbia and the Outlying Areas of the U.S., and Associated Areas (Federal Information Processing Standard 5-2): Washington, Department of Commerce, National Institute of Standards and Technology

Place_Keyword: US

Place_Keyword: NY

Place_Keyword: New York State

Access_Constraints: None

Use_Constraints:

Only that acknowledgement of the U.S. Geological Survey and NYSDEC would be apprecieated in products derived from these data.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Ricardo Lopez-Torrijos

Contact_Organization: New York State Department of Environmental Conservation

Contact_Address:

Address_Type: mailing and physical address

Address: 50 Wolf Rd

City: Albany

State_or_Province: New York

Postal_Code: 12233-3507

Contact_Voice_Telephone: 518-457-0726

Contact_Electronic_Mail_Address: rxlopez@dec.state.ny.us

Native_Data_Set_Environment:

24,000 scale hypsographic contour linework drawn by photogrametric, plane table or other methods by USGS, US Army Corp of Engineers, Tennesy Valley Authority or others. Linework copied onto stable-base mylar. Raster image of linework created by USGS, Reston, with Optronics drum scanner at an aperture of 20um, to give an equivalent resolution of 1024 DPI. Raster data converted to vector with line-center algorithm in LT4X v. 3.1, 11/11/93, by John Dabritz of Infotec Development Inc. Grid elevations calculated with 8-profile weighted linear interpolation, with cubic smoothing of slope at the contour line as per algorithm in above mentioned LT4X v. - export in DEM format, UTM meters, - grid height and width of 10 mt, - clipping (overedge) coordinate in UTM mt, - input coord feet or meters (depending on source material), output in meters/decimeters, - DEM grid points which are on a profile section longer than 80 mt are smoothed by passing the grid through a low pass-filter twice. The filter size (see below) is of 9 cell diameters (aprox 9 mt). The purpouse here is to leave well-contoured areas untouched while smoothing areas of less than 5-2.5% slope (to lessen streaking in flat areas typical of multiple-profile DEM derivation). - cubic smoothing of elevation profile across contours to 35% of the distance between adjacent contours. This profiles have a smaller, but still discontinuous change in slope at contour intersection than if not rounded. - 9 cell diameter for smoothing reach, - use all 8 directions (from grid point to N, S, E, W ,NE, NW, SE, SW) for each cell, - no line feeds. export dem <contour data name> 2 10.00 10.00 2 1 4 80 2 0.35 9 8 0

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

The digital elevation model is composed of an elevation value linked to a grid cell location representing a gridded form of a topographic map hypsography overlay. Each grid cell entity contains an 8-character value between -32,767.0 and 32,768.0.

Entity_and_Attribute_Detail_Citation:

U.S. department of the Interior, U.S. Geological Survey, 1992, Standards for digital elevation models: Reston, VA, a hypertext version of the Digital Elevation Models - Data users Guide 5 is available at: <http://edcwww.cr.usgs.gov/glis/hyper/guide>