medem10

Citation:

Citation Information:

Originator: U.S. Geological Survey
Publication Date: 200307
Title: medem10
Geospatial Data Presentation Form: raster digital data
Series Information:

Series Name: Maine GIS Data Catalog; Maine GIS SDE Server

Publication Information:

Publication Place: Augusta ME
Publisher: Maine Office of Geographic Information Systems (MEGIS)

Other Citation Details:
10 meter digital elevation models, MEDEM10s, are downloadable in zipped GRID format at http://megis.maine.gov/catalog. MEDEM10.DEM Ascii text files from which the grids were generated will download with the grids. The digital elevation models are developed as part of the orthorectification process. Availability will roughly precede the anticipated delivery dates for the high resolution orthophotography project. A status map of showing the expected order of MEDEM10 development will be made available at http://www.maine.gov/geolib/ortho%20committee/highresolorthoproject.htm.
Online Linkage: http://megis.maine.gov/catalog

Description:

Abstract:
MEDEM10s are digital terrain elevation models of Maine, in grid format, based on USGS 7.5 minute DEMs (10 by 10 m square grid or data spacing). Digital Elevation Model (DEM) is the terminology adopted by USGS to describe terrain elevation data sets in a digital raster form.The standard DEM consists of an array of elevations from ground positions at regularly spaced intervals, cast on a designated coordinate projection system, produced in 7.5 by 7.5 minute blocks from cartographic map contour overlays or scanned National Aerial Photography (NAPP_ photographs. USGS DEM data are stored as profiles with a 10 or 30 meter square grid spacing inwhich the spacing of elevations along and between each profile is in regular whole number intervals. USGS has used four methods to collect DEM data. Of these, only one, interpolation from vectors or digital line graph (DLG) hypsographic and hydrographic data is currently used for 7.5 minute DEMs and other series. MEDEM10s, produced using 1:24000 cartographic map contour overlays, represent the 10 meter profile of USGS 7.5 minute DEM series.
Purpose:
MEDEM10'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 volumetric analysis, for site location of towers, or for drainage basin delineation. These data were collected as part of the National Mapping Program. Not intended for uses at scales greater than 1:24,000. Users must assume responsibility in determining the useability of this data for their purpose. Data at this scale may be useful for detailed studies and local planning.
Supplemental Information:
MEDEM10 development is in progress as part of the Maine Library of Geographic Information (GeoLibrary) high resolution orthophotography development and acquisition. More information on completion status of the project represented by this coverage is available at http://www.maine.gov/geolib/projects.htm .
Time Period of Content:

Time Period Information:

Range of Dates/Times:

Beginning Date: 2003
Ending Date: Present

Currentness Reference: publication date

Status:

Progress: In Work
Maintenance and Update Frequency: continually

Spatial Domain:

Bounding Coordinates:

West Bounding Coordinate: -71.3
East Bounding Coordinate: -66.8
North Bounding Coordinate: 47.6
South Bounding Coordinate: 42.9

Keywords:

Theme:

Theme Keyword Thesaurus: Maine GIS Thesaurus-Theme
Theme Keyword: imageryBaseMapsEarthCover
Theme Keyword: 24000
Theme Keyword: IMAGERY AND REMOTE SENSING
Theme Keyword: elevation
Theme Keyword: altitude
Theme Keyword: digital elevation model
Theme Keyword: digital terrain model
Theme Keyword: hypsography
Theme Keyword: contours
Theme Keyword: raster
Theme Keyword: relief

Place:

Place Keyword Thesaurus: Maine GIS Thesaurus-Place
Place Keyword: Maine
Place Keyword: United States of America

Stratum:

Stratum Keyword Thesaurus: Maine GIS Thesaurus-Stratum
Stratum Keyword: land surface

Access Constraints:
Secondary distribution by permission only. Please see Maine Office of Geographic Information Systems (MEGIS) License Agreement at http://megis.maine.gov/ . Any secondary distribution must have this documentation appended.
Use Constraints:
Users must assume responsibility in determining the usability of this data for their purposes. Digital maps retain the accuracy of their source materials. The best use of data mapped at scales of 1:500,000 and 1:250,000 is in statewide planning and studies; at 1:100,000 in regional planning and studies; at 1:62,500 and 1:24,000 in detailed studies and local planning; and at 1:12,000 and 1:5,000 or larger scales in parcel level studies and detailed local planning. In the use of Maine GIS data, please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the most recent copy of both data and metadata from the Maine GIS Data Catalog. The Maine Office of Geographic Information Systems (MEGIS) provides notice of updates and corrections directly to the Maine GIS Technical Group and Maine GIS Users, through the MEGISTECH and MEGISUSER list servers. To subscribe please contact the MEGIS technical support line at (207) 287-6144. To request data correction in, or provide updates to, Maine GIS data a feedback form is available at http://megis.maine.gov/, or you may contact MEGIS directly. MEGIS is not responsible for local edits to data or metadata. Updates, corrections, and feedback, incorporated in the Maine GIS database are made in accordance with "Data Standards for Maine Geographic Information Systems", 2002, and coordinated by MEGIS in consultation with the Maine GIS Executive Council.
Point of Contact:

Contact Information:

Contact Organization Primary:

Contact Organization: (MEGIS) Maine Office of Geographic Information Systems

Contact Address:

Address Type: mailing address
Address: State House Station 145
City: Augusta
State or Province: ME
Postal Code: 04333-0145
Country: USA

Contact Voice Telephone: (207) 287-6144
Contact Facsimile Telephone: (207) 287-4563
Hours of Service: Monday through Friday 0800 - 1700 EST

Data Set Credit: Credit should always be given to the data source and/or originator when the data is transferred or printed.
Native Data Set Environment: ArcInfo version 9, Solaris 9, pathname = /home24/dems/24k/tiles/<tile_name>/medem10, file size ~1.25 MB; Maine GIS SDE, sdeusers, sde, Bureau of Information Services (BIS) Oracle 9i
Cross Reference:

Citation Information:

Originator: U.S. Geological Survey (USGS), Maine Office of Geographic Information Systems (MEGIS) (ed.)
Publication Date: 20010131
Publication Time: Unknown
Title: medem30
Geospatial Data Presentation Form: raster digital data
Series Information:

Series Name: Maine GIS Data Catalog; Maine GIS SDE Server

Publication Information:

Publication Place: Augusta ME
Publisher: Maine Office of Geographic Information Systems

Other Citation Details: 24000
Online Linkage: http://megis.maine.gov/catalog/

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:
Data profiles for this product do not always have the same number of elevations because of the variable angle between true north and north in the Universal Transverse Mercator (UTM) projection coordinate system. The 7.5 minute DEM data have rows and columns that vary in length and are staggered. The UTM bounding coordinates form a quadrilateral in which no two sides are parallel to each other, rather than a rectangle. If a rectangle is required for the user's application, the user will need to pad out the uneven rows and columns with blanks or flagged data values. Some software vendors have incorporated this function into their software for input of the standard formatted USGS DEMs.

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 http://rmmcweb.cr.usgs.gov/nmpstds/demstds.html .

Completeness Report:
Coverage for the State of Maine is complete. 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.


MEDEM10s, generated from vector data derived from scanned raster files of USGS 1:24,000 scale map series contour separates, 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 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.

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.

Quantitative Horizontal Positional Accuracy Assessment:

Horizontal Positional Accuracy Explanation: RMSE of the DEM-Digital elevation models meet horizontal National Map Accuracy Standards (NMAS) accuracy requirements.

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. 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.

Quantitative Vertical Positional Accuracy Assessment:

Vertical Positional Accuracy Value: 7
Vertical Positional Accuracy Explanation:
MEDEM10s, generated from vector data derived from scanned raster files of USGS 1:24,000 scale map series contour separates. have been processed or smoothed for consistency and edited to remove identifiable systematic errors.

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.

Lineage:

Source Information:

Source Citation:

Citation Information:

Originator: U.S. Geological Survey (USGS)
Publication Date: multiple dates
Publication Time: Unknown
Title: (24k) USGS 1:24,000 scale quadrangles
Geospatial Data Presentation Form: map
Series Information:

Series Name: National Mapping Program Standard Series Topographic Maps
Issue Identification: USGS 7.5 Minute Map Series

Publication Information:

Publication Place: Reston VA
Publisher: U.S. Geological Survey

Other Citation Details: 24000 Publication date is unique to each quadrangle in the map series. Standard 7.5x7.5 minute quadrangles cover geographic areas of 49 to 71 square miles. 1 inch at map scale represents 2000 feet.
Online Linkage: http://mapping.usgs.gov/mac/maplists/howtoselectmaps.html

Source Scale Denominator: 24000
Type of Source Media: stable-base material (mylar)
Source Time Period of Content:

Time Period Information:

Range of Dates/Times:

Beginning Date: 1/1/1948
Beginning Time: Unknown
Ending Date: Present
Ending Time: Unknown

Source Currentness Reference: publication date

Source Citation Abbreviation: 24k
Source Contribution: Hypsographic vector information which is interpolated to regular grid posts to form DEM grids in 10 by 10 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.

MEDEM10s are generated from vector data derived from scanned raster files of USGS 1:24,000 scale map series contour separates.


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.

Process Date: 2003
Process Contact:

Contact Information:

Contact Organization Primary:

Contact Organization: (USGSHIGHRES) U.S. Geological Survey

Process Step:

Process Description:
The delivered product 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).

These were:

Process Date: 200307
Process Contact:

Contact Information:

Contact Organization Primary:

Contact Organization: (MEGIS) Maine Office of Geographic Information Systems

Contact Address:

Address Type: mailing address
Address: State House Station 145
City: Augusta
State or Province: ME
Postal Code: 04333-0145
Country: USA

Contact Voice Telephone: (207) 287-6144
Contact Facsimile Telephone: (207) 287-4563
Hours of Service: Monday through Friday 0800 - 1700 EST

Indirect Spatial Reference: sample 1:24000 scale tile
Direct Spatial Reference Method: Raster
Raster Object Information:

Raster Object Type: Grid Cell
Row Count: 1000
Column Count: 1500
Vertical Count: 1

Horizontal Coordinate System Definition:

Planar:

Grid Coordinate System:

Grid Coordinate System Name: Universal Transverse Mercator 1983
Universal Transverse Mercator:

UTM Zone Number: 19
Transverse Mercator:

Scale Factor at Central Meridian: 0.9996
Longitude of Central Meridian: -69
Latitude of Projection Origin: 0
False Easting: 500000
False Northing: 0

Planar Coordinate Information:

Planar Coordinate Encoding Method: Coordinate Pair
Coordinate Representation:

Abscissa Resolution: 1
Ordinate Resolution: 1

Planar Distance Units: meters

Geodetic Model:

Horizontal Datum Name: North American Datum of 1983
Ellipsoid Name: Geodetic Reference System 80
Semi-major Axis: 6378137
Denominator of Flattening Ratio: 298.257

Vertical Coordinate System Definition:

Altitude System Definition:

Altitude Datum Name: National Geodetic Vertical Datum of 1929

Detailed Description:

Entity Type:

Entity Type Label: MEDEM10.VAT
Entity Type Definition: value attribute table
Entity Type Definition Source: Environmental Systems Research Institute, Inc. (ESRI)

Attribute:

Attribute Label: COUNT
Attribute Definition: number of pixels with a given value

Attribute:

Attribute Label: VALUE
Attribute Definition: grid interpolated elevation in meters

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 interger value from -32767 to 32,768.
Entity and Attribute Detail Citation:
Standards for Digital Elevation Models,1993, U.S. Department of Interior (USDOI), U.S. Geological Survey (USGS), Reston, VA.
A .pdf version is available at:
http://rmmcweb.cr.usgs.gov/nmpstds/demstds.html .

Distributor:

Contact Information:

Contact Organization Primary:

Contact Organization: (MEGIS) Maine Office of Geographic Information Systems

Contact Address:

Address Type: mailing address
Address: State House Station 145
City: Augusta
State or Province: ME
Postal Code: 04333-0145
Country: USA

Contact Voice Telephone: (207) 287-6144
Contact Facsimile Telephone: (207) 287-4563
Hours of Service: Monday through Friday 0800 - 1700 EST

Distribution Liability:
Users must assume responsibility to determine the usability of this data for their purposes. Although these data have been processed successfully on a computer system at the Maine Office of Geographic Information Systems, no warranty expressed or implied is made by MEGIS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Neither the Maine Office of Geographic Information Systems, nor any of its contributors, are liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets.
Standard Order Process:

Digital Form:

Digital Transfer Information:

Format Name: GRID
Format Version Number: GRID 9.x
Format Specification: ESRI Grid

Digital Transfer Option:

Online Option:

Access Instructions: Anyone with an Internet browser can view and download these data from http://megis.maine.gov/catalog/. Please follow instructions on the website for the Internet Data Catalog.

Fees: Data may be downloaded from Maine GIS Internet Data Catalog at no charge.
Turnaround: Data is available for immediate download from the Maine GIS Internet Data Catalog.

Standard Order Process:

Non-digital Form: map
Fees:
MEGIS does some custom mapping, with available Maine GIS data, as time allows. If you have a custom mapping question please call the technical support line at (207) 287-6144 and ask about an estimate for your mapping needs.
Turnaround: 15 working days

Custom Order Process:
MEGIS provides technical support for Maine GIS data, estimates on custom mapping, and consultation on data and application development, as time permits. You may call (207) 287-6144 with questions about Maine GIS data, and to inquire about assistance with your GIS environment.

Metadata Date: 7/1/2003
Metadata Review Date:
Metadata Future Review Date:
Metadata Contact:

Contact Information:

Contact Organization Primary:

Contact Organization: (MEGIS) Maine Office of Geographic Information Systems

Contact Address:

Address Type: mailing address
Address: State House Station 145
City: Augusta
State or Province: ME
Postal Code: 04333-0145
Country: USA

Contact Voice Telephone: (207) 287-6144
Contact Facsimile Telephone: (207) 287-4563
Hours of Service: Monday through Friday 0800 - 1700 EST

Metadata Standard Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata Standard Version: FGDC-STD-001-1998
Metadata Use Constraints:
Please confirm that you are using the most recent copy of both data and metadata from the Maine GIS Data Catalog. The Maine Office of Geographic Information Systems (MEGIS) provides notice of updates and corrections directly to the Maine GIS Technical Group and Maine GIS Users through the MEGISTECH and MEGISUSER list servers. To subscribe please contact the MEGIS technical support line at (207) 287-6144. To request correction in, or updates to, Maine GIS data a feedback form is available at http://megis.maine.gov/, or you may contact MEGIS directly. MEGIS is not responsible for local edits to data or metadata. Updates, corrections, and feedback incorporated in the Maine GIS database are made in accordance with "Data Standards for Maine Geographic Information Systems", 2002, and coordinated by MEGIS in consultation with the Maine GIS Executive Council.