GRANIT Home GRANIT Header





GIS Event Calendar
August
1234
567891011
12131415161718
19
202122232425
262728293031



Digital Elevation Model - Quad 21 - ERROL, NH

Digital Elevation Model - Quad 21 - ERROL, NH

Metadata also available as - [Parseable text] - [SGML] - [XML]

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Complex Systems Research Center, University of New Hampshire
Publication_Date: 19990301
Title: Digital Elevation Model - Quad 21 - ERROL, NH
Edition: One
Geospatial_Data_Presentation_Form: Map
Publication_Information:
Publication_Place: Durham, New Hampshire
Publisher: Complex Systems Research Center, University of New Hampshire
Other_Citation_Details: None
Online_Linkage:
<URL:http://www.granit.sr.unh.edu/cgi-bin/nhsearch?dset=dem/dem021>
Larger_Work_Citation:
Citation_Information:
Originator: Complex Systems Research Center, University of New Hampshire
Publication_Date: 19860101
Title: NH GRANIT Database
Publication_Information:
Publication_Place: Durham, New Hampshire
Publisher: Complex Systems Research Center, University of New Hampshire
Online_Linkage: <URL:http://www.granit.sr.unh.edu>
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 includes 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's provided through GRANIT are standard USGS 7.5-minute files reprocessed to conform to GRANIT standards, as described below. The elevation values are reported in feet, and are spaced at 30-meter intervals along and between each profile.

Purpose:
DEM's can be used as source data for generating digital orthophotos, and/or as layers in geographic information systems for earth science analysis (e.g. contour, slope, hillshade derivatives).
Supplemental_Information:
Data distribution tile: 7.5-minute quadrangle.

Note that the DEMs are in an ASCII file format, e.g. standard USGS DEM format, and require conversion to be used within standard GIS packages. Most packages will provide a utility to accomplish this conversion.

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19790701
Ending_Date: Present
Currentness_Reference: Ground Condition
Status:
Progress: In work
Maintenance_and_Update_Frequency: Irregular
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -71.250
East_Bounding_Coordinate: -71.125
North_Bounding_Coordinate: 44.875
South_Bounding_Coordinate: 44.750
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
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: United States
Place_Keyword: Northeast
Place_Keyword: New England
Place_Keyword: New Hampshire
Place_Keyword: ERROL, NH
Access_Constraints: None
Use_Constraints: Not for legal use
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Browse_Graphic:
Browse_Graphic_File_Name:
<URL:http://www.granit.sr.unh.edu/cgi-bin/load_file?PATH=/data/database/d-webdata/dem/browse.gif>
Browse_Graphic_File_Description: gif image file
Browse_Graphic_File_Type: gif
Data_Set_Credit: GRANIT database
Native_Data_Set_Environment:
ASCII DEM


Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
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 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. (Note, however, that GRANIT has re-processed the data since retrieval from USGS, as referenced in the Process Description section.)
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.

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 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.
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.

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.

Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:
US Geological Survey or another mapping agency in cooperation with USGS
Publication_Date: Unknown
Title: 7.5-minute Digital Elevation Models
Edition: 1
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Other_Citation_Details: None
Online_Linkage: <URL:http://edcwww.cr.usgs.gov/webglis>
Larger_Work_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: National Cartographic Database
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Online_Linkage: <URL:http://www.usgs.gov>
Source_Scale_Denominator: 24000
Type_of_Source_Media: Digital file
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19790101
Ending_Date: Present
Source_Currentness_Reference: Publication Date
Source_Citation_Abbreviation: DEM-1
Source_Contribution:
The USGS DEM files provided the basic information (both horizontal and vertical) for the GRANIT DEMs.
Source_Information:
Source_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: Digital Contour Lines
Edition: 1
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Other_Citation_Details: None
Online_Linkage: <URL:http://edcwww.cr.usgs.gov/webglis>
Larger_Work_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: National Cartographic Database
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Online_Linkage: <URL:http://www.usgs.gov>
Source_Scale_Denominator: 24000
Type_of_Source_Media: Magnetic tape
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19790101
Ending_Date: Present
Source_Currentness_Reference: Ground Condition
Source_Citation_Abbreviation: CONTOUR-2
Source_Contribution:
Hysographic 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.
Source_Information:
Source_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: Photo ID Number
Edition: 1
Geospatial_Data_Presentation_Form: Remote-sensing Image
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Other_Citation_Details: None
Online_Linkage: <URL:http://edcwww.cr.usgs.gov/webglis>
Larger_Work_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: National Cartographic Database
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Online_Linkage: <URL:http://www.usgs.gov>
Type_of_Source_Media: Transparency
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: Unknown
Ending_Date: Present
Source_Currentness_Reference: Ground Condition
Source_Citation_Abbreviation: PHOTO-2
Source_Contribution: Elevation values
Source_Information:
Source_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: 19890101
Title: Project Control
Edition: 1
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Other_Citation_Details: None
Online_Linkage: <URL:http://edcwww.cr.usgs.gov/webglis>
Larger_Work_Citation:
Citation_Information:
Originator: US Geological Survey
Publication_Date: Unknown
Title: National Cartographic Database
Publication_Information:
Publication_Place: Reston, VA
Publisher: US Geological Survey
Online_Linkage: <URL:http://www.usgs.gov>
Type_of_Source_Media: Magnetic tape
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: Unknown
Ending_Date: Present
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: CONTROL-2
Source_Contribution: Ground control points
Process_Step:
Process_Description:
The source DEM files were reprocessed to conform to GRANIT database standards. Key elements of the processing included:

- reprojecting the spatial data from UTM meters (Zone 18/19), NAD27 to NH State Plane feet, Zone 4676, NAD83. - standardizing all Z-values to feet

The specific steps applied to each data file included the following:

1. Data for each quad was retrieved from the USGS web site in STDS format as a tarred, compressed (gzipped) file. (<http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/7_min_dem/states/NH.html>) 2. The single files were uncompressed and untarred into quad-specific directories. (usage: gunzip -c 30.2.nnnn.tar.gz | tar -xpvf - ) 3. In Imagine: a) Load the *IDEN.DDF data to create the *.img file b) Convert the *.img file to an Arc/Info compatible GRID 4. In Arc/Info: a) Run STDSINFO and record relevant parameters b) Run PROJECTDEFINE on the grid c) Check cell size of each grid, and standardize to to meters if necessary d) Reproject the GRID to NH State Plane feet, NAD83 e) Convert Z-units from meters to feet, if necessary f) Convert all edge values from their default value of -32767 to "no data" g) Run LATTICEDEM to convert GRID back to ASCII DEM format

Source_Used_Citation_Abbreviation: DEM-1
Process_Date: 19990301
Source_Produced_Citation_Abbreviation: Version 1
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Process_Step:
Process_Description:
All preliminary process steps were performed by USGS in the development of the source DEM's, as described below.

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.

Source_Used_Citation_Abbreviation: CONTOUR-2, PHOTO-2, CONTROL-2
Process_Date: unknown


Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid cell


Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1983
State_Plane_Coordinate_System:
SPCS_Zone_Identifier: New Hampshire
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.999967
Longitude_of_Central_Meridian: -71.666667
Latitude_of_Projection_Origin: 42.500000
False_Easting: 984249.999900
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: Row and column
Coordinate_Representation:
Abscissa_Resolution: 30
Ordinate_Resolution: 30
Planar_Distance_Units: meters
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: GRS 80
Semi-major_Axis: 20925604.4720406
Denominator_of_Flattening_Ratio: 298.26


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 hysography 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,

A hypertext extract is available at: URL: <http://edc.usgs.gov/glis/hyper/guide/usgs_dem>

Softcopies in ASCII and WordPerfect format are available at: URL: <ftp://mapping.usgs.gov/pub/ti/DEM/>

U.S.Department of the Interior, U.S. Geological Survey, 1992, Standards for digital elevation models: Reston, VA,

Softcopies in ASCII and WordPerfect format are available at: URL: <ftp://mapping.usgs.gov/pub/ti/DEM/>


Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Resource_Description: DEM21 - 7.5-Minute Digital Elevation Model for Quad 21
Distribution_Liability:
Digital data in NH GRANIT represent the efforts of the contributing agencies to record information from the cited source materials. Complex Systems Research Center, under contract to the NH Office of State Planning, and in consultation with cooperating agencies, maintains a continuing program to identify and correct errors in these data. OSP, CSRC, and the cooperating agencies make no claim as to the validity or reliability or to any implied uses of these data.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: DEM
Format_Information_Content:
USGS standard DEM: The standard USGS DEM can be described as an ASCII formatted elevation file preceded by a metadata header file which consists of one 1024 byte ACSII record.
Transfer_Size: 1.0 Mb
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: <URL:http://www.granit.sr.unh.edu>
Fees:
No charge when downloaded from the internet. Cost of reproduction for provision on CD/ROM or other media.
Ordering_Instructions:
Mail or fax a copy of the GRANIT "Data Request Form" from the GRANIT Data Catalog. Delivery Time: Two weeks
Technical_Prerequisites:
Ability to read/convert standard USGS DEM formatted-files.


Metadata_Reference_Information:
Metadata_Date: 20000601
Metadata_Review_Date: 20000601
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: Mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Metadata_Standard_Name: FGDC CSDGM
Metadata_Standard_Version: FGDC-STD-001-1998

Generated by mp version 2.8.13 on Thu Dec 13 10:07:17 2007
CSRC EOS UNH Send Email to GRANIT Directions to Morse Hall Contact Bar