DEM 30 Meter Index

7.5 Digital Elevation Models - DEM - 30 meter - Index for the State of Nebraska

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Nebraska Department of Natural Resources in work-share agreement with the U.S. Geological Survey
Publication_Date: 199701
Title:
7.5 Digital Elevation Models - DEM - 30 meter - Index for the State of Nebraska
Geospatial_Data_Presentation_Form: raster digital data
Publication_Information:
Publication_Place: Lincoln, Nebraska - United States
Publisher: Nebraska Department of Natural Resources in work-share
Online_Linkage: digital-elevation-models
Description:
Abstract:
Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a regular array of elevations cast on a designated coordinate projection system. The DEM data are stored as a series of profiles in which the spacing of the elevations along and between each profile is in regular whole number intervals. The normal orientation of data is by columns and rows. Each column 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). 7.5-minute Level-2 DEM (30- by 30-m data spacing, cast on Universal Transverse Mercator (UTM) projection). Provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle without over edge. Coverage is for the state of Nebraska
Purpose:
DEM's can be used as source data for digital orthophotos, and, as layers in geographic information systems, for earth science analysis. DEM's can also serve as tools for natural resources, watershed planning, flood plain management, river basin studies, for site location of towers, or for drainage basin delineations as well as project reviews and evaluations.
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 DNR DEMs.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 199701
Ending_Date: Present
Currentness_Reference:
ground condition
Status:
Progress: In work
Maintenance_and_Update_Frequency: Irregular
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -103.128525
East_Bounding_Coordinate: -102.996100
North_Bounding_Coordinate: 41.752066
South_Bounding_Coordinate: 41.622967
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: elevation
Theme_Keyword: imageryBaseMapsEarthCover
Theme_Keyword: geoscientificInformation
Place:
Place_Keyword_Thesaurus: U.S. Department of Commerce, 1977, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions (Federal Information Processing Standard 10-3):Washington, D.C., National Institute of Standards and Technology.
Place_Keyword: NE
Place_Keyword: County
Place_Keyword: Quadrangle
Place_Keyword: USA
Place:
Place_Keyword_Thesaurus: U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of The United States, and associated areas (Federal Information Processing Standard 5-2): Washington, D. C., National Institute of Standards and Technology.
Place_Keyword: FIPS code of Nebraska
Place:
Place_Keyword_Thesaurus: U.S. Department of Commerce,1990, Counties and equivalent entities of The United States, its possessions, and associated areas (Federal Information Processing Standard 6-4): Washington, D.C. National Institute of Standards and Technology.
Place_Keyword: FIPS code for Nebraska.
Access_Constraints: None
Use_Constraints:
None. Acknowledgement of the cooperative efforts of the Nebraska Natural Resources Commission and the U.S. Geological Survey would be appreciated in products derived from this data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nebraska Department of Natural Resources
Contact_Position: GIS Coordinator
Contact_Address:
Address_Type: mailing and physical address
Address:
301 Centennial Mall South, P.O. Box 94676
City: Lincoln
State_or_Province: Nebraska
Postal_Code: 68509-4676
Contact_Voice_Telephone: 402-471-2363
Contact_Facsimile_Telephone: 402-471-2900
Contact_Electronic_Mail_Address: dnr.gis@nebraska.gov
Hours_of_Service: 8:00-5:00 CST
Contact Instructions:
http://dnr.ne.gov
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.3000
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
The accuracy of a Level-2 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 that may be extracted from a given source during digitization.
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:
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.
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 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.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
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. 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. Level-2 DEMS have better resolution that Level-1 DEMS. 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.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: Unknown
Publication_Time: Unknown
Title:
digital contour lines
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Source_Scale_Denominator: 24000
Type_of_Source_Media: magnetic tape or CD-ROM
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19790701
Ending_Date: unknown
Source_Currentness_Reference:
ground condition
Source_Citation_Abbreviation:
contour1
Source_Contribution:
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.
Process_Step:
Process_Description:
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. The Nebraska Natural Resources Commission developed Level-2 DEMs for the entire state of Nebraska. 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 dissemination by the Nebraska Department of Natural Resources, and archiving in the National Digital Cartography Data Base (NDCDB) utilizing the Digital Elevation Model Verification System (DVS) software.
Source_Used_Citation_Abbreviation:
CONTOUR1, PHOTO1, CONTROL1
Process_Date: Unknown
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nebraska Department of Natural Resources
Contact_Position: GIS Coordinator
Contact_Address:
Address_Type: mailing and physical address
Address:
301 Centennial Mall South, P.O. Box 94676
City: Lincoln
State_or_Province: Nebraska
Postal_Code: 68509-4676
Country: USA
Contact_Voice_Telephone: 402-471-2363
Contact_Facsimile_Telephone: 402-471-2900
Contact_Electronic_Mail_Address: gis@dnr.ne.gov
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 470
Column_Count: 357
Vertical_Count: 1
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:
UTM_Zone_Number: 13
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.999600
Longitude_of_Central_Meridian: -105.000000
Latitude_of_Projection_Origin: 0.000000
False_Easting: 500000.000000
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: row and column
Coordinate_Representation:
Abscissa_Resolution: 30.000000
Ordinate_Resolution: 30.000000
Planar_Distance_Units: meters
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1927
Ellipsoid_Name: Clarke 1866
Semi-major_Axis: 6378206.400000
Denominator_of_Flattening_Ratio: 294.978698
Vertical_Coordinate_System_Definition:
Altitude_System_Definition:
Altitude_Datum_Name: National Geodetic Vertical Datum of 1929
Altitude_Resolution: 1
Altitude_Distance_Units: meters
Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
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Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
The digital elevation model is composed of a 6-character integer raster representing a gridded form of a topographic map hypsography overlay. Each raster entity contains a 6-character integer value between -32,767 to 32,768.
Entity_and_Attribute_Detail_Citation:
U.S.Department of the Interior, U.S. Geological Survey, Digital Elevation Models -- Data Users Guide; Reston, VA,
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nebraska Department of Natural Resources
Contact_Position: GIS Coordinator
Contact_Address:
Address_Type: mailing address
Address:
301 Centennial Mall South, P.O. Box 94676
City: Lincoln
State_or_Province: Nebraska
Postal_Code: 68509-4676
Contact_Voice_Telephone: 402 471-2363
Contact_Facsimile_Telephone: 402 471-2900
Contact_Electronic_Mail_Address: dnr.gis@nebraska.gov
Resource_Description: Downloadable Data
Distribution_Liability:
None
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: DEM
Format_Version_Date: 199701
Transfer_Size: 0.300
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: http://www.dnr.state.ne.us
Access_Instructions:
Access the data through our web site by <http://www.dnr.state.ne.us>. Enter ther Data Bank Option; Enter the Spatial/GIS Data Option; Enter the DEM Database; There are several options for download.
Offline_Option:
Offline_Media: CD-ROM
Recording_Capacity:
Recording_Density: 700
Recording_Density_Units: MB
Recording_Format: maybe compressed
Fees: The online copy of the data set may be retrieved via web at no charge. For delivery of digital data in other formats there may be an additional charge plus the cost of the media.
Ordering_Instructions:
You can either order by leaving a message over the web site or call Nebraska Department of Natural Resources
Available_Time_Period:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1997
Ending_Date: unknown
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Metadata_Reference_Information:
Metadata_Date: 20090921
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nebraska Department of Natural Resources
Contact_Position: GIS Coordinator
Contact_Address:
Address_Type: mailing address
Address:
301 Centennial Mall South, P.O. Box 94676
City: Lincoln
State_or_Province: Nebraska
Postal_Code: 68509-4676
Country: USA
Contact_Voice_Telephone: 402 471-2363
Contact_Facsimile_Telephone: 402 471-2900
Contact_Electronic_Mail_Address: dnr.gis@nebraska.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Extensions:
Online_Linkage: http://www.esri.com/metadata/esriprof80.html
Profile_Name: ESRI Metadata Profile
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