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U.S. Geological Survey

30 Meter Digital Elevation Model

This page last update: 07/23/2001 3:35:34 PM
metadata created using Minnesota Geographic Metadata Guidelines .


Go to Section:
1. Identification Information
2. Data Quality Information
3. Spatial Data Organization Information
4. Spatial Reference Information
5. Entity and Attribute Information
6. Distribution Information
7. Metadata Reference Information
 
 
Section 1  Identification Information - - - - - - top
Originator  U.S. Geological Survey 
Title  30 Meter Digital Elevation Model 
System Name  dem30im3 
Abstract  This 30 Meter DEM is a copy of the USGS 1:24,000 scale Level 2 DEMs for the State. There are three quadrangles known be be Level 1 DEM data: Town Line Lake (q1925), Grand Portage (q1261) and Grand Portage OE N (q1161). 
Purpose  Landscape analysis, hillshade generation for cartographic products, slope determination 
Time Period of Content Date  Unknown 
Currentness Reference  The dates of source aerial photography have not been researched at this time. Date information will be added to this description when it becomes available. 
Progress  Complete 
Maintenance and Update Frequency  None planned 
Spatial Extent of Data  Statewide coverage is available with the exception of low relief areas in the Red River Valley. A h 
Bounding Coordinates  E = -89
W = -97.5
N = 49.5
S = 43
Place Keywords  Minnesota
Theme Keywords  Digital Elevation Models, DEM, Topography 
Theme Keyword Thesaurus  None 
Access Constraints  None 
Use Constraints  None 
Contact Person Information  Tim Loesch, GIS Application Coordinator
DNR-MIS
500 Lafayette Road
St. Paul, MN 55155-4011
Phone: (651) 296-0654
FAX: (651) 297-4946
E-mail: tim.loesch@dnr.state.mn.us 
Browse Graphic File Name  dem30im3_sam.gif
Browse Graphic File Description 
Associated Data Sets  The DEM was produced by the USGS in concert with the development of other data sets in their product line. The Minnesota DEM's are closely allied with the Digital Orthophotoquad product currently under development at the USGS, which is being distributed during 1995-1996. These products should register well, although they exist at different spatial resolutions (30 meters versus 1 meter). 
 
Section 2  Data Quality Information - - - - - - top
Attribute Accuracy  The data does not carry attributes separate from elevation, which are characterized in the Vertical Positional Accuracy Section. 
Logical Consistency  The data exists within a consistent data structure consistent with ARC GRID requirements. 
Completeness  Complete coverage exists with the exception of low-relief areas in northwestern Minnesota 
Horizontal Positional Accuracy  Unknown 
Vertical Positional Accuracy  Vertical accuracy specifications for dem DEM data depend on the production methodology, photogrammetric source, and degree of editing. A vertical RMSE of 7 meters or less is the desired accuracy standard. A RMSE of 15 meters is the maximum permitted. Distinct north-south tonal banding is visible in quads with larger RMSE's. This data noise becomes especially prevalent in derived products, such as hillshades, aspect, and slope layers. 
Lineage  The U.S.G.S. has been designated as a lead federal agency for the collection and distribution of digital cartographic data including Digital Elevation Model (DEM) data. All DEM data are similar in logical data structure and are ordered from south to north in profiles that are ordered from east to west. Dem data in 7.5 minute units consist of regular arrays of elevations arranged horizontally on the Universal Transverse Mercator (UTM) coordinate system of NAD27. These data are stored as profiles with 30 meter spacing along and between each profile. There are four production methods for DEM data in 7.5 minute quad form. The first is the Gestalt Photo Mapper II which is an automated photogrammetric system. Other methods include: manual profiling from photogrammetric stereomodels using stereoplotters, interpolation of the elevations from the stereomodel digitized contours, interpolation from digital line graph hypsographic and hydrographic data. Information on which method was used to develop each data set is stored with each source file, although it is not carried through the conversion process. The results of positional accuracy tests, expressed as a Root Mean Square Error (RMSE) is also stored in the source file. If any user wishes to obtain information from the source files for a particular data set, it can be obtained upon request from the Central Office GIS Lab staff. The data was originally delivered to the Land Management Information Center (LMIC) who produced a set of CD-ROMs for interim distribution purposes. LMIC processed these DEMs into EPPL7 format, converting them to UTM Zone 14, NAD83 Datum and setting all Z-Unit values to feet. This EPPL7 file was then delivered to DNR where it was converted to an Arc/Info Grid file. In January, 2001 an update was made to the DEM, incorporating approximately 230 quadrangles of updated Level 2 information. During this process lake elevations were also smoothed using the DNR lake elevation dataset. If the DEM elevation within the lake differed by less than five feet, the surface was set at the lake elevation. Any greater differences were deemed dangerous to modify without closer scrutiny. Approximately 88 quadrangles in the Metropolitan area were created from 1:24,000 scale USGS DLG Hypsography files. These files were converted to Arc/Info coverage format and then converted to a 30 meter DEM using a surface modelling program called ANUDEM. 
Source Scale Denominator  24000 
 
Section 3  Spatial Data Organization Information - - - - - - top
Native Data Set Environment  ARC GRID 
Geographic Reference for Tabular Data  None 
Spatial Object Type  Raster 
Vendor Specific Object Types  Integer Grid 
Tiling Scheme  71/2 Minut 
 
Section 4  Spatial Reference Information - - - - - - top
Horizontal Coordinate Scheme  UTM 
Ellipsoid  GRS1980 
Horizontal Datum  NAD83 
Horizontal Units  meters 
Distance Resolution  meters 
Altitude Datum  NGVD29 
Altitude Units  feet 
Depth Datum  n/a 
Depth Units  n/a 
Cell Width  30 
Cell Height  30 
Latitude Resolution 
Longitude Resolution 
UTM Zone Number  15 
SPCS Zone Identifier 
County Coordinate Zone Identifier 
Coordinate Offsets or Adjustments  n/a 
Map Projection Name  n/a 
Map Projection Parameters  n/a 
Other Coordinate System's Definition  n/a 
 
Section 5  Entity and Attribute Information - - - - - - top
Entity and Attribute Overview  Elevation values in a regular 30 meter sampling matrix 
Entity and Attribute Detailed Citation 

HTML Table

 
Section 6  Distribution Information - - - - - - top
Publisher  Minnesota DNR - MIS Bureau 
Publication Date  2/1/1996 
Contact Person Information  Robert Maki, GIS Database Coordinator
Minnesota DNR
500 Lafayette Road, Box 11
St. Paul, MN 55155
Phone: (651) 297-2329
FAX: (651) 297-4946
E-mail: robert.maki@dnr.state.mn.us 
Distributor's Data Set Identifier  dem30im3 
Distribution Liability  None stated 
Transfer Format Name  7.1.2 
Transfer Format Version Number  ARC/INFO 
Transfer Size  421 
Ordering Instructions Contact above Person 
Online Linkage  DNR Data Deli
 
Section 7  Metadata Reference Information - - - - - - top
Metadata Date  3/29/1999 
Contact Person Information  Tim Loesch, GIS Applications Programmer
Minnesota DNR - MIS Bureau
500 Lafayette Road
St. Paul, MN 55155
Phone: 651-296-0654
FAX: 651-297-4946
E-mail: tim.loesch@dnr.state.mn.us 
Metadata Standard Name  Minnesota Geographic Metadata Guidelines 
Metadata Standard Version  1.1 
Metadata Standard Online Linkage  http://www.lmic.state.mn.us/gc/stds/metadata.htm