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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 | 0
Longitude Resolution | 0
UTM Zone Number | 15
SPCS Zone Identifier | 0
County Coordinate Zone Identifier | 0
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