SMMS METADATA REPORTChoose this link for a metadata search or this link to browse the Data Catalog. medem30 Identification_Information Data_Quality_Information Spatial_Data_Organization_Information Spatial_Reference_Information Entity_and_Attribute_Information Distribution_Information Metadata_Reference_Information Identification Information Section Index Citation: 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/ Description: Abstract: MEDEM30s are digital terrain elevation models of Maine, in grid format, based on USGS 7.5 minute DEMs (30- by 30- m data spacing). 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. Purpose: MEDEM30'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. Time Period of Content: Time Period Information: Range of Dates/Times: Beginning Date: 7/1/1979 Beginning Time: Unknown Ending Date: 1/31/2001 Ending Time: Unknown Currentness Reference: source dates Status: Progress: Complete Maintenance and Update Frequency: None planned Spatial Domain: Bounding Coordinates: West Bounding Coordinate: -72 East Bounding Coordinate: -66 North Bounding Coordinate: 48 South Bounding Coordinate: 42 Keywords: Theme: Theme Keyword Thesaurus: Maine GIS Thesaurus-Theme Theme Keyword: 24000 Theme Keyword: dem Theme Keyword: digital elevation model Theme Keyword: hypsography Theme Keyword: altitude Theme Keyword: digital contours Theme Keyword: contours Theme Keyword: elevation Theme Keyword: quadrangles Theme Keyword: raster Theme Keyword: relief Theme Keyword: digital terrain model Theme Keyword: IMAGERY AND REMOTE SENSING Theme Keyword: NATURAL RESOURCES AND TOPOGRAPHY Theme Keyword: imageryBaseMapsEarthCover Place: Place Keyword Thesaurus: Maine GIS Thesaurus-Place Place Keyword: Maine Place Keyword: Gulf of Maine Stratum: Stratum Keyword Thesaurus: Maine GIS Thesaurus-Stratum Stratum Keyword: human dimensions 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 8.3, Solaris 7, pathname = /home24/dems/24k/tiles//medem30. image file size ~1.04 MB; Maine GIS SDE, sdeusers, sde, Bureau of Information Services (BIS) Oracle 9i Data Quality Information Section Index 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. 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. 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 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. 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: 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. Quantitative Vertical Positional Accuracy Assessment: Vertical Positional Accuracy Explanation: 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: U.S. Geological Survey (USGS) Publication Date: 19790701 Publication Time: Unknown Title: (30mdem) 7.5 minute digital elevation model Geospatial Data Presentation Form: raster digital data Series Information: Series Name: USGS Digital Elevation Models Issue Identification: 7.5 minute dem Publication Information: Publication Place: Reston VA Publisher: U.S. Geological Survey Other Citation Details: 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/ Online Linkage: http://edc.usgs.gov/glis/hyper/guide/usgs_dem Source Scale Denominator: 999999 Type of Source Media: online Source Time Period of Content: Time Period Information: Range of Dates/Times: Beginning Date: 7/1/1979 Beginning Time: Unknown Ending Date: Present Ending Time: Unknown Source Currentness Reference: source dates Source Citation Abbreviation: 30mdem Source Contribution: 7.5 minute USGS DEMs were tiled to USGS 7.5 minute map extents to create MEDEM30s. 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. 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. Process Date: unknown Source Produced Citation Abbreviation: 30mdem Process Contact: Contact Information: Contact Organization Primary: Contact Organization: (USGSGNIS) U.S. Geological Survey Contact Position: Chief, Geographic Names Information Section Contact Address: Address Type: mailing and physical address Address: 523 National Center City: Reston State or Province: VA Postal Code: 20192 Country: USA Contact Voice Telephone: (703) 648-4551 Contact Electronic Mail Address: rwrocest@usgs.gov Process Step: Process Description: The Maine Office of GIS received the 30 meter DEMs (National Elevation Dataset) from the USGS in two large grids that covered the entire state (east and west). These two grids were merged together into one larger grid using the merge command in ArcInfo Grid. This one large, statewide grid was then clipped to the extent of each quadrangle using the MEGIS 7.5 minute map series index, 24KINDEX. To eliminate the "void" value areas along the borders, the grids were buffered by 100 meters and the edges of adjacent grids were merged to fill in the "void" values. This process of creating 30 meter DEMs by quad was undertaken to provide a manageable data size for distribution from the MEGIS website. Source Used Citation Abbreviation: 30mdem Process Date: 20001207 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 Spatial Data Organization Information Section Index Direct Spatial Reference Method: Raster Raster Object Information: Raster Object Type: Grid Cell Spatial Reference Information Section Index 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: 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: Geodetic Reference System 80 Semi-major Axis: 6378206 Denominator of Flattening Ratio: 294.9786982 Vertical Coordinate System Definition: Altitude System Definition: Altitude Datum Name: National Geodetic Vertical Datum of 1929 Altitude Resolution: 1 Altitude Distance Units: meters or feet Altitude Encoding Method: Explicit elevation coordinate included with horizontal coordinates Entity and Attribute Information Section Index 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, 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 Section Index 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: ARCE Format Version Number: ARC Version 8.3 Format Specification: ARC/INFO Export Format ASCII File Structure: Case Sensitive: false Format Information Content: An Arc/Info export file is an interchange format used to transfer spatial data, INFO data files, and other ESRI ARC/INFO files between various machine types. Export files have the suffix .e00 and contain, in fixed-length ASCII format, all spatial information available for each feature. The command IMPORT is available in A/I to convert the export file to original format, i.e. coverage, grid, or other spatial data file. Import will add a spatial data file and a related INFO file to a machine directory. ESRI's ArcView is packaged with an import utility called IMPORT71 for the same export file conversion. The utility is also available through the FREE software link on the Maine GIS Data Catlaog under "CDProducts" at http://megis.maine.gov/catalog/ or from ESRI at http://www.esri.com/. CARE MUST BE TAKEN after import, not to separate the spatial information from its related INFO file. Since export files are in ASCII format make sure any file transfer method like FTP is executed under ASCII mode. Binary transfer will not work correctly. 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. Digital Transfer Option: Online Option: Access Instructions: Where file size and Internet access permit, data requests can be made available via File Transfer Protocol (FTP) from the ftp address ftp://ftp.state.me.us/. Digital Form: Digital Transfer Information: Format Name: ESRI Shapefile Format Version Number: ARC Version 8.3 Format Specification: ArcView Shapefile Format ASCII File Structure: Case Sensitive: false Format Information Content: MEGIS will soon make all data in the internet Data Catalog available in ESRI's ArcView shapefile format. This additional format will first be available for E911 data under the TOWNS tab. A shapefile is a simple non-topological format that stores the geometry and attribute information for a set of geographic features as a set of vector (point, line, polygon) coordinates. Shapefiles draw quickly and directly in ArcView; you can create your own data using the shapefile format; an existing ARC/INFO coverage can be converted to a shapefile; other spatial data formats can be converted to shapefiles. Three files are created for each shapefile: .shp stores the feature geometry (shape and location information); .shx stores the index of the feature geometry; .dbf a dBASE (TM) file stores the attribute information for the features. Other index files may be created to help speed analysis and query: these file formats are .sbn .sbx .ain .aix .fbn and .fbx. In addition you may find projection .prj, and metadata .xml, files associated with shapefiles. CAUTION: When you edit an existing theme or shapefile you are creating a new dataset or at least a new version of a dataset; give the dataset a new name or a version identifier to reflect your edits. Be prepared to fully document your sources and to both quantify and qualify the edits you make in order to facilitate coordination with other data sources. PLEASE NOTE: conversion to shapefile format changes some characters ( # - .) to underscores; item names over 10 characters are truncated. An effort will be made over time to consider these limitations in item names, and to eliminate the use of these characters in Maine GIS data development. It should not be assumed that a conversion from shapefile back to coverage would produce the same data file as found in the original coverage format. The results of such a conversion are greatly improved by the use of PRECISION setting DOUBLE, DOUBLE and careful management of tolerances. Digital Transfer Option: Online Option: Access Instructions: Anyone with an internet browser can view and download these data from the http address http://megis.maine.gov/catalog/. Please follow instructions on the website for the internet Data Catalog. Digital Transfer Option: Online Option: Access Instructions: Where file size and internet access permit, data requests can be filled via File Transfer Protocol (FTP) from the ftp address ftp://ftp.state.me.us/. Fees: Data may be downloaded from Maine GIS Data Catalog at no charge. Turnaround: Data is available for immediate download from the Maine GIS 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 Reference Information Section Index Metadata Date: 7/1/2000 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 Metadata Standard Version: FGDC-STD-001-1998 Metadata Access Constraints: none 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. MetaWeb Metadata report generated Thursday, 01/April/2004