Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: unknown
Title: Index of Digital Elevation Models (DEM), New York
Geospatial_Data_Presentation_Form: vector digital data
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Description:
Abstract: This is an index of all the available DEM (digital elevation model) tiles within New York state. Download links are provided for each quad. Each DEM raster has a pixel resolution of approximately 10 meters. Elevation values were derived from USGS contour lines mapped at a scale of 1:24,000.
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: 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,
elevations in decimeters) 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.
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: 1995
Currentness_Reference: process date
Status:
Progress: Complete
Maintenance_and_Update_Frequency: Irregular
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -79.75
East_Bounding_Coordinate: -71.75
North_Bounding_Coordinate: 45.0
South_Bounding_Coordinate: 40.5
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: digital elevation model
Theme_Keyword: digital terrain model
Theme_Keyword: hypsography
Theme_Keyword: altitude
Theme_Keyword: topography
Theme_Keyword: index map
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: elevation
Theme:
Theme_Keyword_Thesaurus: CUGIR Category
Theme_Keyword: index map
Theme_Keyword: elevation
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: New York
Access_Constraints: None
Use_Constraints: 1. The NYS DEC and the U.S. Geological Survey asks to be
credited in derived products. 2. Secondary Distribution of the data
is not allowed. 3. Any documentation provided is an integral part of
the data set. Failure to use the documentation in conjunction with
the digital data constitutes misuse of the data. 4. Although every
effort has been made to ensure the accuracy of information, errors
may be reflected in the data supplied. The user must be aware of
data conditions and bear responsibility for the appropriate use of
the information with respect to possible errors, original map scale,
collection methodology, currency of data, and other conditions.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: New York State Department of Environmental
Conservation. Division of Water
Contact_Position: Watershed Geographic Information Technologies Support
Group, Chief
Contact_Address:
Address_Type: mailing and physical address
Address: 625 Broadway
Address: 4th floor
City: Albany
State_or_Province: New York
Postal_Code: 12233-3500
Contact_Voice_Telephone: 518-402-8259
Contact_Instructions: All questions regarding metadata and/or data should go
through the internal DEC contact.
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, Tennessee 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 purpose 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. These 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
Cross_Reference:
Citation_Information:
Originator: US Geological Survey
Publication_Date: unknown
Title: Digital Elevation Model (DEM)
Attribute_Accuracy:
Attribute_Accuracy_Report: 10 mt gridding cell spacing is the maximun that can be
meaningfully extracted from hypsography contour lines. This
allows very good hypsographic contour reproduction in all areas
except very flat ones. Elevation_resolution_ is 1 decimeter (0.1
meter). Elevation accuracy is 24,000 contour data, i.e.
plus/minus half the contour interval.
Logical_Consistency_Report: The fidelity of the relationships encoded in the data structure
of the DEM are automatically verified using a USGS software program
upon completion of the data production cycle. The test verifies full
compliance to the DEM specification.
Completeness_Report: DEM visually inspected using Delta3D version 2.0, 1995 by John
Dabritz and S. Phan of Infotec Development Inc. Checked for
completness and drainage characteristics matching the USGS
Hydrography Digital Line Graphs published at the same time as the
model. Further validation for logical consistency performed previous
to submission for archiving.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: The horizontal accuracy of the DEM is expressed as an
estimated root mean square error (RMSE). The estimate of the
RMSE is based upon horizontal accuracy tests of the DEM
source materials with equal to or less than intended
horizontal RMSE error of the DEM. The testing of horizontal
accuracy of the source materials is accomplished by
comparing the planimetric (X and Y) coordinates of
well-defined ground points with the coordinates of the same
points as determined from a source of higher accuracy.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 3 meters (estimated)
Horizontal_Positional_Accuracy_Explanation: Digital elevation models meet horizontal National
Map Accuracy Standards (NMAS) accuracy
requirements.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report: A vertical RMSE of one-half of the contour interval of
the source map is the maximum permitted. Systematic errors
may not exceed the contour interval of the source graphic.
Level 2 DEMs have been processed or smoothed for consistency
and edited to remove identifiable systematic errors.
Quantitative_Vertical_Positional_Accuracy_Assessment:
Vertical_Positional_Accuracy_Value: 6 to 8 meters
Vertical_Positional_Accuracy_Explanation: DEMs meet vertical National Map Accuracy Standards
(NMAS) accuracy requirements. Vertical Positional
Accuracy Vaue varies with each quad.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: Unknown
Publication_Time: Unknown
Title: Albany
Publication_Information:
Publication_Place: EROS Data Center, SD
Publisher: U.S. Geological Survey
Type_of_Source_Media: mylar separate from original color separation plate
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: unknown
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: CONTOUR1
Source_Contribution: elevation values for interpolation
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey or National Geodetic
Survey (NGS) (ed.)
Publication_Date: Unknown
Publication_Time: Unknown
Title: project control
Publication_Information:
Publication_Place: EROS Data Center, SD
Publisher: U.S. Geological Survey
Type_of_Source_Media: field notes
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: unknown
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: CONTROL1
Source_Contribution: ground control points
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey (ed.)
Publication_Date: Unknown
Publication_Time: Unknown
Title: photo ID number
Publication_Information:
Publication_Place: EROS Data Center, SD
Publisher: U.S. Geological Survey
Type_of_Source_Media: transparency
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: unknown
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: PHOTO1
Source_Contribution: elevation values from photogrametry
Process_Step:
Process_Description: The process can be seen as divided into several tasks,
each with associated sub-processes. A. Original Data Source
Preparation: 1. The United States Geological Service (USGS)
office of Map Production (Mid Continent Mapping Center,
Rolla, MO) selects the most recent original printing plates
(1:24,000 or 1:25,000 scale) for each published quadrangle
map. These plates are archived under controlled
environmental conditions and are produced from the original
map scripting materials onto dimensionally stable material
(Mylar). A copy of the separate is made by contact methods
onto photosensitive, opaque, dimensionally stable material.
The separate plate copy is shipped to the USGS Mapping
Applications Center (Reston, VA). 2. The MAC scans the
separate plate with an Ektaprint (a.k.a. Optronics) drum
scanner with an aperture of 24um (corresponding to a linear
resolution of approx 1030 DPI) into a run-length encoded
(RLE) formatted raster file. Contours lines have typically a
thickness of 25 to 30 pixels. The file, typically between 10
and 20 Mb, would be checked for completeness and distortion.
If satisfactory MAC forwards both the raster file, the plate
separate and the corresponding published quadrangle to the
digitization workshop at the New York State Department of
Environmental Conservation Water GIS unit in Albany, NY. B.
Raster file batch processing 1. The raster file was loaded
into Line Tracer for X Windows (LT4X, Infotec Inc.,
Portland, Oregon) version 3.1. With it is georegistered and
trimmed of any excess margin. 2. The file is put through an
automated raster-to-vector batch process in which a vector
following the center of the raster line is created, with a
minimum vertex separation of 25 pixels. Once the vector has
been calculated and the topology of the resultant data
established, the resolution of the original raster was
reduced to 500 DPI, to allow faster processing in the
succeeding steps. C. Vector Contour Edit, Edge Matching and
Labeling. 1. The vectorized contours are edited carefully to
correct any line breaks, vector webbing (due to pen
thickness or lack of resolution of the original's drafting
process), labels and special line symbols (depressions, road
fills, etc). 2. The contours are labeled with their
corresponding elevations, as tagged in the original
material. 3. The eight adjoining maps' vector contours are
brought in and checked against those of the map being
edited. Vectors of matching labels are snapped together if
the gap is less than 3 line-thicknesses. Otherwise they are
tagged as "disagreement in the original" (see DLG standards
for hypsography layer). For each border only one of the maps
is edited. 4. An independent quality control check of
contour edits and labeling is carried out. 5. The Digital
Elevation Model is interpolated in a batch process (see
"Native Dataset Environment" above). D. DEM Edit and Quality
Control 1. The resultant DEM is loaded in Delta3D (Infotec
Inc., Portland, OR) v. 2.1, together with the corresponding
hydrography vectors. The DEM is checked for the presence of
irregular patterns, in which case it is returned to the
previous process; water body height (e.g. in large lakes) is
set for all grid cells within the water body; and drainage
along vector streams is enforced by lowering cells higher
than the upstream one along the stream. Water retention
areas (wetlands, marshes...) are not modified except for
stream entrance and exit. - Edge matching with the adjoining
eight DEMs. 2. From thirty to thirty-five height reference
markers are collected from the corresponding cultural
separate for the quadrangle. These are compared to heights
as read from the DEM and an statistical RMS is calculated,
this is recorded in the DEM's C record. 3. The quadrangle
record A is filled and checked for consistency. 4. A final
DEM-formatted elevation dataset for the quadrangle is
recorded. E. Final Quality Control and Databasing 1. The DEM
file is shipped to USGS's Rocky Mountain Mapping Center
(Boulder, CO). There it undergoes a separate quality control
process which essentially mimics D. 2. The corresponding
quality control flags are established. The DEM is
sub-sampled to 30 mt grid spacing and the resultant file is
forwarded to USGS's EROS Data Center, were it is catalogued
into the National Elevation database. The 10 mt grid spacing
file is returned to NYS DEC, from where it is forwarded to
Cornell University's Mann Library.
Process_Date: Unknown
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Albert R. Mann Library
Contact_Address:
Address_Type: mailing and physical
Address: Cornell University
City: Ithaca
State_or_Province: New York
Postal_Code: 14853
Contact_Voice_Telephone: 607-255-5406
Distribution_Liability: Cornell University provides these geographic data "as is". Cornell
University makes no guarantee or warranty concerning the accuracy of
information contained in the geographic data. Cornell University further
makes no warranty either expressed or implied, regarding the condition of
the product or its fitness for any particular purpose. The burden for
determining fitness for use lies entirely with the user. Although these
files have been processed successfully on computers at Cornell University,
no warranty is made by Cornell University regarding the use of these data
on any other system, nor does the fact of distribution constitute or imply
any such warranty.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: GeoJSON
Format_Information_Content: OpenIndexMaps
Transfer_Size: 0.08
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: metadata
Format_Information_Content: FGDC XML metadata
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: HTML metadata
Format_Information_Content: FGDC HTML metadata
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Fees: None
Metadata_Date: 20190524
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Albert R. Mann Library
Contact_Address:
Address_Type: mailing and physical
Address: Albert R. Mann Library
City: Ithaca
State_or_Province: New York
Postal_Code: 14853
Country: USA
Contact_Voice_Telephone: 607-255-5406
Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
