U.S. Geological Survey EROS Data Center1999WDEQ.SDE.wyo_dem_30mSioux Falls, SDU. S. Geological SurveyServer=159.238.120.157; Service=5151; Database=WDEQ; User=SDE; Version=sde.DEFAULTServer=159.238.120.157; Service=5151; Database=WDEQ; User=SDE; Version=sde.DEFAULTWDEQ.SDE.wyo_dem_30mSDE raster digital data
The U.S. Geological Survey has developed a National Elevation
Dataset (NED). The NED is a seamless mosaic of best-available
elevation data. The 7.5-minute elevation data for the conterminous
United States are the primary initial source data. In addition to the
availability of complete 7.5-minute data, efficient processing
methods were developed to filter production artifacts in the existing
data, convert to the NAD83 datum, edge-match, and fill slivers of
missing data at quadrangle seams. One of the effects of the NED
processing steps is a much-improved base of elevation data for
calculating slope and hydrologic derivatives.
NED has a resolution of one arc-second (approximately 30 meters).
Please see the USGS NED website for a more detailed description
of the NED at: <URL:http://edcnts12.cr.usgs.gov/ned/ned.html>.
NED for Wyoming is distributed in 1:100,000-scale quadrangle
blocks (56 in Wyoming) and in Universal Transverse Mercator
projection, either zone 12 or zone 13, North American Datum
of 1983.
Geospatial elevation data are utilized by the scientific and resource
management communities for global change research, hydrologic
modeling, resource monitoring, mapping, and visualization
applications.
en19791994REQUIRED: The year (and optionally month, or month and day) for which the data set corresponds to the ground.publication date of source mapsIrregular-111.055369-104.05231345.00557440.994740-111.055369-104.05231340.99474045.005574noneDEMdigital elevation modeldigital terrain modelhypsographyaltitudeheightcontour linedigital contoursnoneWyomingNoneNone.Data ManagerSpatial Data and Visualization Centermailing address
Box 4008 University Station
LaramieWyoming82071USA307-766-2751n/a8:00 - 5:00 MSTMicrosoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.3500SDE Raster Dataset
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published accuracy information on NED is not yet available.
The accuracy of a DEM is dependent upon the level of
detail of the source and the grid spacing used to sample
that source. The primary limiting factor for the level of
detail of the source is the scale of the source materials.
The proper selection of grid spacing determines the level
of content thatmay be extracted from a given source
during digitization.
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published accuracy information on NED is not yet available.
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.
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published accuracy information on NED is not yet available.
See also the Process Steps for a description of methodology
in assembling NED.
The DEM is visually inspected for completeness on a DEM view
and edit system for the purpose of performing a final quality
control and if necessary edit of the DEM. The physical format
of each digital elevation model is validated for content
completeness and logical consistency during production quality
control and prior to archiving in the National Digital
Cartographic Data Base.
Due to the variable orientation of the quadrilateral in relation
to the Universal Transverse Mercator (UTM) projection grid,
profiles that pass within the bounds of the DEM quadrilateral,
may be void of elevation grid points, and are not represented
in the DEM. This condition occurs infrequently and is always the
first or last profile of the dataset.
Level 2 DEM: Level 2 DEM's may contain void areas due to
interruptions to contours in the source graphic or DLG. Void
area elevation grid posts are assigned the value of -32,767. In
addition, suspect elevation areas may exist in the DEM but are
not specifically identified. Suspect areas can be located on the
source graphic as a "disturbed surface, " symbolized by
contours overprinted with photorevised or other surface
patterns.
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published accuracy information on NED is not yet available.
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 which are selected as equal to or less
than intended horizontal RMSE error of the DEM.
The testing of horizontal accuracy of the source
materials isaccomplished 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.
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published accuracy information on NED is not yet available.
The vertical RMSE statistic is used to describe the
vertical accuracy of a DEM, encompassing both
random and systematic errors introduced during
production of the data. The RMSE is encoded in
element number 5 of record C of the DEM.
Accuracy is computed by a comparison of linear
interpolated elevations in the DEM with
corresponding known elevations. Test points are
well distributed, representative of the terrain, and
have true elevations with accuracies well within
the DEM accuracy criteria. Acceptable test points
include, in order of preference: field control,
aerotriangulated test points, spot elevations, or
points on contours from existing source maps
with appropriate contour interval. A minimum of
28 test points per DEM is required to compute the
RMSE, which is composed of a single test using 20
interior points and 8 edge points. Edge points are
those which are located along, at, or near the
quadrangle neatlines and are deemed by the
editor to be useful to evaluating the accuracy of
the edge of the DEM. Collection of test point data
and comparison of the DEM with the quadrangle
hypsography are conducted by the quality control
units within the USGS.
There are three types of DEM vertical errors;
blunder, systematic and random. These errors
are reduced in magnitude by editing but cannot be
completely eliminated. Blunder errors are those
errors of major proportions and are easily
identified and removed during interactive editing.
Systematic errors are those errors that follow
some fixed pattern and are introduced by data
collection procedures and systems. These error
artifacts include: vertical elevation shifts,
misinterpretation of terrain surface due to trees,
buildings and shadows, and fictitious ridges, tops,
benches or striations. Random errors result from
unknown or accidental causes.
DEM's are edited to correctly depict elevation
surfaces that correspond to water bodies of
specified size.
Level 1 DEM: A RMSE of 7-meters or less is the
desired accuracy standard. A RMSE of 15-meters
is the maximum permitted. A 7.5-minute DEM at
this level has an absolute elevation error
tolerance of 50 meters (approximately three
times the 15-meter RMSE) for blunder errors for
any grid node when compared to the true
elevation. Any array of points in the DEM can not
encompass more than 49 contiguous elevations
in error by more than 21 meters (three times the
7-meter RMSE). Systematic errors that are
within stated accuracy standards are tolerated.
Level 2 DEM: A vertical RMSE of one-half of the
contour interval, determined by the source map,
is the maximum permitted. Systematic errors
may not exceed one contour interval,
determined by the source map, is the maximum
permitted. Systematic errors may not exceed
one contour interval specified by the source
graphic. Level 2 DEMs have been processed or
smoothed for consistency and edited to remove
identifiable systematic errors.
U.S. Geological Survey1997digital contour linesmapReston, VAU.S. Geological Surveymagnetic tape19791994ground conditionCONTOUR1
hypsographic vector information which is interpolated to regular
grid posts to form DEM grids in 30- by 30- meter UTM data spacing
within the 7.5 minute DEM bounds.
U.S. Geological Surveyunknownphoto ID numberremote-sensing imageReston, VAU.S. Geological Surveytransparency19791994ground conditionPHOTO1elevation valuesU.S. Geological Surveyunknownproject controlmapReston, VAU.S. Geological Surveymagnetic tape19791994ground conditionCONTROL1ground control points
Please see the USGS NED methodology available at:
<URL: http://edcnts12.cr.usgs.gov/ned/Methodology.htm>
This information is based on published information about
Digital Elevation Models (DEM's) from which NED was assembled.
Published process information on NED is not yet available.
The production procedures, instrumentation,
hardware and software used in the collection of
standard U. S. Geological Survey (USGS) Digital
Elevation Models (DEM's) vary depending on
systems used at the contractor, cooperator or
National Mapping Division (NMD) production sites.
This process step describes, in general, the
process used in the production of standard USGS
DEM datasets.
Level 1 DEM: Level 1 DEM's are acquired
photogrammetrically by manual profiling or image
correlation techniques from National Aerial
Photography Program (NAPP) or equivalent
source photographs. Level 1 30-minute DEM's
may be derived or resampled from level 1 7.5-
minute DEM's.
Level 2 DEM: Level 2 DEM's are produced by
converting 1:24,000-scale and 1:100,000-scale
hypsography digital line graph (DLG) data to DEM
format or the DEM's are generated from vector
data derived from scanned raster files of USGS
1:24.000-scale or 1:100,000-scale map series
contour separates.
Level 3 DEM: Level 3 DEM's are created from DLG
data that has been vertically integrated with all
categories of hypsography, hydrography, ridge
line, break line, drain files and all vertical and
horizontal control networks. The production of
level 3 DEMs requires a system of logic
incorporated into the software interpolation
algorithms that clearly differentiates and
correctly interpolates between the various types
of terrain, data densities and data distribution.
Water body editing: DEM surface areas
corresponding to water bodies are flattened and
assigned map specified or estimated surface
elevations. Water body areas are defined as
ponds, lakes, and reservoirs that exceed 0.5
inches at map scale and double line drainage that
exceeds 0.25 inches at map scale. Water body
shorelines are derived either from a hypsographic
DLG or by interactive delineation from 1:24,000-
scale or 1:100,000-scale USGS map series.
Edge matching: DEM datasets within a project area
(consisting of a number of adjacent files) are edge
matched to assure terrain surface continuity
between files. Edge matching is the process of
correcting adjacent elevation values along common edges.
The objective of edge matching is to create more accurate
terrain representations by correcting the alignment of
ridges and drains, and overall topographic shaping within
an approximately 25-30 row or column grid post
zone on both edges.
Quality control: DEM's are viewed on interactive
editing systems to identify and correct blunder
and systematic errors. DEM's are verified for
physical format and logical consistency at the
production centers and before archiving in the
National Digital Cartographic Data Base (NDCDB)
utilizing the Digital Elevation Model Verification
System (DVS) software.
CONTOUR1, PHOTO1, CONTROL1unknownMetadata imported.C:\DOCUME~1\RKIRKW~1\LOCALS~1\Temp\xml731.tmp20050922RasterPixel14439252110.0002780.000278321Upper LeftFALSELZ771pixel codesTRUESDRNorth American Datum of 1983Geodetic Reference System 806378137.000000298.257222GCS_North_American_1983Decimal degrees0.0000000.000000row and column0.0002780.000278Explicit elevation coordinate included with horizontal coordinates1.000000
The digital elevation model is composed of a 6-
character integer raster representing a gridded form of
a topographic map hypsography overlay, with a value in meters.
In Wyoming, elevations range from approximately 900-4200 meters.
U.S.Department of the Interior, U.S. Geological Survey, 1992,
Standards for digital elevation models: Reston, VA,
Data ManagerSpatial Data and Visualization Centermailing address
Box 4008 University Station
LaramieWyoming82071USA307-766-2751n/a
The distributor shall not be held liable for improper or
incorrect use of this data, based on the description of
appropriate/inappropriate used described in this metadata
document.
ARCE (Arc/Info export)7.0.41995Export file was created using defaults, no compression1399.4871399.487ftp.sdvc.uwyo.edu or http://www.sdvc.uwyo.edu/clearinghousehttp://www.sdvc.uwyo.edu/clearinghouse/howto.html
Both the ftp and WWW server which this data is available
from is a Silicon Graphics Challenge server, running
the IRIX 6.2 UNIX operating system.
No fees are required for downloading the data that is on-line.
Some fees may be required to cover costs of tapes if data is
required on tape media.
Downloadable Data20100601Margo Berendsenmailing address
Box 4008 University Station
LaramieWyoming82071USA307-766-2751meh@uwyo.eduREQUIRED: The person responsible for the metadata information.REQUIRED: The organization responsible for the metadata information.FGDC Content Standards for Digital Geospatial MetadataFGDC-STD-001-1998enlocal timehttp://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile{343DC63B-D45D-4E9F-B012-01E060F82209}2005092211160900FALSE20100601111031002010060111103100CopyRaster P:\NSR\GIS\ArcViewMaps\Monitoring\Network_Plan_RK\DEM\wyo_dem P:\NSR\GIS\ArcViewMaps\Monitoring\Network_Plan_RK\DEM\DEM_30M.gdb\wyo_dem # # # NONE NONE #CopyRaster "P:\AQRM Program\Monitoring\Mapping\DEM\Hillshade.gdb\wyo_dem_30m" "Database Connections\WDEQ_SDE.sde\WDEQ.SDE.wyo_dem_30m" # # # NONE NONE #BuildPyramids "Database Connections\WDEQ@SDE.sde\WDEQ.SDE.WYO_DEM_30M"CalculateStatistics "Database Connections\WDEQ@SDE.sde\WDEQ.SDE.WYO_DEM_30M" 1 1 #Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.3500WYO_DEM_30M-111.055369-104.05231345.00557440.994741-111.055369-104.05231345.00557440.994741image servicewdeq30M DEMImage service of the 30M DEM.ISO 19115 Geographic Information - MetadataDIS_ESRI1.0dataset002Server=159.238.120.157; Service=5151; Database=WDEQ; User=SDE; Version=sde.DEFAULTArcSDE Connection1399.487SDE Raster DatasetGCS_North_American_198321252110.000278Degree144390.000278Degree20100601