contours

Identification Information

Citation Information

Originator	U.S. Geological Survey (USGS), Maine Office of Geographic Information Systems (MEGIS) (comp., ed.)
Publication Date	20000430
Publication Time	Unknown
Title	contours
Geospatial Data Presentation Form	vector digital data
Series Name	Maine GIS
Issue Identification	SDE server; Internet Data Catalog
Publication Place	Augusta ME
Publisher	Maine Office of Geographic Information Systems (MEGIS)
Online Linkage	http://megis.maine.gov/catalog/
Beginning Date	19480101
Beginning Time	Unknown
Ending Date	19931231
Ending Time	Unknown

Abstract

CONTOURS contains contour lines for Maine from USGS 1:24,000 scale quadrangles; in accordance with the source, units may be in feet or meters and intervals may be at 10 to 20 feet, or 3 meters. Additional supplementary contours exist on some of the quads. Due to the large number of arcs, elevation codes are spot checked from a representative sample. Please report any elevation coding errors to the Maine Office of GIS. The data retains the edgematching discrepancies existing in the source.

Purpose

The contours are useful for determining drainage, using with Arc/Info Grid module for hydrology studies, determining slope and delineating watersheds. If used in hydrology, care should be given to cell size for modeling. It is recommended that in coastal plain areas, a cell size of no more than 22.5 meters be used.

Time Period of Content

Beginning Date	19480101
Beginning Time	Unknown
Ending Date	19931231
Ending Time	Unknown
Currentness Reference	source dates

Status

Progress	Complete
Maintenance and Update Frequency	As needed

Bounding Coordinates

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

Keywords

Theme	hypsography, contours, contour, digital contours (Maine GIS Thesaurus-Theme)
Theme	elevation, imageryBaseMapsEarthCover (ISO Keyword Thesaurus)
Place	Maine, New Brunswick, New Hampshire, Quebec, United States (Maine GIS Thesaurus-Place)
Stratum	land surface (GCMD Parameter Keyword)

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 correct copy of both data and metadata from the Maine GIS Data Catalog. 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.

Contact Organization

(MEGIS) Maine Office of Geographic Information Systems

Contact Person

GIS Coordinator

Contact Position

GIS Coordinator

Address Type

mailing address

Address

State House Station 174

City

Augusta

State or Province

Postal Code

04333-0174

Country

USA

Contact Voice Telephone

207 624-7700

Contact Facsimile Telephone

207 287-3842

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

Maine Office of Information Technology (OIT) Oracle 9i, Maine Office of Geographic Information Systems (MEGIS), Maine GIS SDE, SDEUSER, SDE.DEFAULT, Maine GIS Internet Data Catalog http://megis.maine.gov/catalog/

Attribute Accuracy Report

Attribute accuracy is expected to be good, however, due to the large number of arcs, elevation codes are spot checked from a representative sample. Please report any elevation coding errors to the Maine Office of GIS

Logical Consistency Report

Spatial topology is clean and free of errors.

Completeness Report

Data set is complete.

Horizontal Positional Accuracy Report

Approximate horizontal accuracy is 12 meters, assuming source data meets National Map Accuracy Standards. The data retains the edgematching discrepancies existing in the source.

Horizontal Positional Accuracy Value

Horizontal Positional Accuracy Explanation

Digitizer tolerance specified equivalent to 0.005 digitizer units, RMS error not to exceed 0.005. For each digital map created, a mylar proof plot of that map was made to verify that the original data have been digitized within the accuracy requirements of "Data Standards for Maine Geographic Information Systems, 1990". A proof plot was plotted on mylar at the same scale as the manuscript. All lines on the proof were a linewidth of 0.01 inch or less. By visual inspection of the proof plot against the original 1:24,000 scale data, ninety percent of the cartographic features on a map were found to be digitized within 0.01 inches measured from the centerline or center point of the feature. One hundred percent of all cartographic features were found to be digitized within 0.02 inches.

Vertical Positional Accuracy Report

National Map Accuracy Standard applies to USGS topographic maps. At all map scales, the maximum allowable vertical tolerance is one half the published contour interval. Automation of the project specified that the contour file z value accuracy rate would be at least 99.5%.

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 Name	National Mapping Program Standard Series Topographic Maps
Issue Identification	USGS 7.5 Minute Map Series
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
Beginning Date	19480101
Beginning Time	Unknown
Ending Date	Present
Ending Time	Unknown
[smcisrcc]	publication date

Beginning Date

19480101

Beginning Time

Unknown

Ending Date

Present

Ending Time

Unknown

Source Currentness Reference

publication date

Source Citation Abbreviation

24k

Source Contribution

CONTOURS contains scanned and vectorized contour lines from USGS 7.5 minute mylar separates. In accordance with the source, arcs are coded with elevation in feet or meters. As in the source, contour intervals vary from 10 to 20 feet with additional supplementary contours on some of the quadrangles.

Process Description

Each MaineGIS 1:24000 base layer represents the automation of a thematic layer from a U.S.Geological Survey (USGS) 7.5 minute series 1:24000 scale quadrangle map. Since the early 1990s, Maine Department of Conservation (MEDOC) has led a multi-agency effort to fund the automation of data to serve a diverse suite of state agency applications in areas that include natural resource management, environmental protection, transportation, and human services. Initially eight base layers were identified for conversion to digital files: coast, contours, otrans, ponds, rivers, roads, streams, towns and wetlands. Automation and quality control, of over 700 U.S.G.S. quadrangles that cover the State of Maine, were coordinated by the Maine Office of Geographic Information Systems (MEGIS). Automation was verified using quality control parameters and procedures outlined in MaineGIS "Data Standards for Maine Geographic Information Systems", March 1990. For MaineGIS base layers, a number of contracted sources were used to scan and vectorize the data from mylar separates or the best available media. Digital files were delivered by contractors in Universal Transverse Mercator (UTM) projection, Zone 19 referenced to the North American Datum of 1927 (NAD27) and in ARC/INFO format, the software standard for Maine's statewide GIS. Quads were digitized at a Root Mean Square (RMS) error not to exceed 0.005 and at a fuzzy tolerance equivalent to 0.002 digitizer inches at the scale of the manuscript map. Map features were digitized within the equivalent of 0.01 in. of the original manuscript. Mylar proof plots of the digitized coverages, with USGS tick marks, neatline and legend, were generated at a pen width of 0.01, and at the original scale, and provided by contractors on delivery of each digitized quad. At MEGIS, proof plots were overlaid on original base maps to check registration, linework quality, and completeness. Features were verified by the following standard of accuracy: 90% of the planimetric features on the digital map must be within 0.01 in. of the centerline of that feature on the manuscript map when plotted at the original scale; 100% of all features must be within 0.02 in. Spatial topology was verified to be clean and free of errors by symbolized display of data and reports on screen: no overshoots; no slivers; no open polygons; no unlabelled polygons; no unresolved line segment intersections, no unresolved dangles; for all points, lines and polygons, a single unique user-id number. A coding accuracy of 100% was required for all attributes which were verified by manual comparison of the source with hard copy printouts and/or symbolized display of data on screen. For the CONTOURS layer, USGS contours in mylar separates acquired from Maine Geological Survey and scanned at 300 dpi into a raster image. The raster image was rubbersheeted to USGS neatlines for the individual quads and contours traced in CADCore Tracer software. The final coverage is an Arc/Info coverage with elevation attributed in the .AAT. All digitized quads are intended to match the USGS source, and include discrepancies found in the source, like edgematch, contour interval, unit of measure, and features mapped. Digitized map tiles were documented by contractors, at the time of automation, using a MaineGIS hardcopy Documentation Form for Digital Map Data and an Attribute Coding Description Form. Data from these hardcopy documents were recorded in INFO as a <layer>.doc file and reflected in the .FAT files of each map tile coverage. Documentation and description, as well as development status of each map tile, were also tracked, at MEGIS, in two Microsoft ACCESS databases CATALOG and QUADSTAT. These database formed the basis for an online Data Catalog, that in 1997 provided internet publication and delivery, of MaineGIS data, to state agencies and the public.

Source Used Citation Abbreviation

24k

Contact Organization

(MEGIS) Maine Office of Geographic Information Systems

Contact Person

GIS Coordinator

Contact Position

GIS Coordinator

Address Type

mailing address

Address

State House Station 174

City

Augusta

State or Province

Postal Code

04333-0174

Country

USA

Contact Voice Telephone

207 624-7700

Contact Facsimile Telephone

207 287-3842

Hours of Service

Monday through Friday 0800 - 1700 EST

Process Description

3-D vector contour files were produced by Land Info International from USGS 1:24000 mylar contour separates with tic marks provided by the Maine Office of GIS. After high resolution scanning the image was filtered through a proprietary software application capturing all the contour lines and placing them in a digital form. The image was then cleaned, eliminating any peripheral data not related to contour information. The maps were then assembled using a fully automated vectorization process (LT4X). Map contours were attributed based on elevation or z values and exported as an Arc/Info format. Each map was quality checked to verify accuracy based on the Maine Office of GIS/Land Info International's strict guidelines including, but not limited to a minimal use of a four point registration. A line accuracy using USGS specifications for 1:24000 scale digital line graphs (DLG) was used as well as coding accuracy where the contour file z value accuracy rate was at least 99.5%.

Source Used Citation Abbreviation

24k

Process Date

1999

Contact Organization

(LANDINFO) Land Info International

Contact Position

Account Manager

Address Type

mailing and physical address

Address

2280 South Xanadu Way, STE 280

City

Aurora

State or Province

Postal Code

80014

Country

USA

Contact Voice Telephone

(303) 369-6800

Contact Facsimile Telephone

(303) 369-6955

Process Description

Digital contour files were imported from an Arc/Info export file provided by the contractor to an Arc/Info coverage by running a series of aml processes. Coverages checked for correct projection definition, topology, fuzzy and dangle tolerances, item names and data type. On screen USGS tile name and georeferencing was verified. Screen checks included verification against MEGIS library layers including hydrography, drgclips, transportation, the 1:24000 tile index. A digital elevation model (DEM) was created from the digital contours to visually check for obvious elevation attribute errors. The contours lines themselves were spot checked on screen for elevation line coding accuracy, pinch outs represented by dangling nodes and stand-alone dangling nodes were confirmed to be present on mylar check plots. A paper check plot is produced and compared to an original USGS mylar one quarter of the mylar section at a time to check for registration, for digitization of features within 0.01 inch of the original manuscript and for missing arcs.

Source Used Citation Abbreviation

24k

Process Date

1998

Contact Organization

James W. Sewall Company

Address Type

mailing and physical address

Address

147 Center Street

City

Old Town

State or Province

Postal Code

04468

Country

USA

Contact Voice Telephone

(207) 827-4456

Contact Facsimile Telephone

(207) 827-3641

Process Description

The Maine Office of GIS completed the conversion of all final data layers from NAD27 to NAD83 in July 1999. All the data layers were converted using the ArcInfo (version 7.2.1) NADCON conversion and the "project" command. All data was copied to double precision, projected to NAD83, and then copied back to single precision. It was decided to keep the NAD27 quad structure instead of generating new quad boundaries from NAD83 coordinates - all indexes (quads) were projected to NAD83 by using the same process previously described. All MEGIS data libraries in ArcInfo Librarian were repopulated using the NAD83 indexes and data.

Process Date

19990701

Contact Organization

(MEGIS) Maine Office of Geographic Information Systems

Contact Person

GIS Coordinator

Contact Position

GIS Coordinator

Address Type

mailing address

Address

State House Station 174

City

Augusta

State or Province

Postal Code

04333-0174

Country

USA

Contact Voice Telephone

207 624-7700

Contact Facsimile Telephone

207 287-3842

Hours of Service

Monday through Friday 0800 - 1700 EST

Cloud Cover

Indirect Spatial Reference

sample 1:24000 scale tile Fayette

Direct Spatial Reference Method

Vector

SDTS Point and Vector Object Type

Complete chain

Point and Vector Object Count

1673

[smcaptur]

false

Grid Coordinate System Name

UTM Zone Number

Scale Factor at Central Meridian

0.9996

Longitude of Central Meridian

-69

Latitude of Projection Origin

False Easting

500000

False Northing

Planar Coordinate Encoding Method

Abscissa Resolution

Ordinate Resolution

Planar Distance Units

Horizontal Datum Name

North American Datum of 1983

Ellipsoid Name

Geodetic Reference System 80

Semi-major Axis

6378137

Denominator of Flattening Ratio

298.257

Altitude Datum Name

National Geodetic Vertical Datum of 1929

Altitude Resolution

Elevations shown, according to USGS quadrangle source, to the nearest foot or 0.5 meters. Contour intervals may vary from 10 to 20 feet with additional supplementary contours, or if units are in meters 3 meters, as shown on the USGS source. quadrangle.

Altitude Distance Units

feet or meters (as shown on USGS quadrangle source)

Altitude Encoding Method

Attribute values

Entity Type Label

CONTOURS

Entity Type Definition

arc feature class

Entity Type Definition Source

Environmental Systems Research Institute, Inc. (ESRI)

Attribute Label

ELEVATION

Attribute Definition

elevation of arc in feet

Beginning Date of Attribute Values

Attribute Label

UNITS

Attribute Definition

unit of measure

Beginning Date of Attribute Values

Attribute Measurement Frequency

Unknown

Entity and Attribute Overview

Each contour is coded with the elevation measured in units.

Entity and Attribute Detail Citation

The ArcView shapefile and ArcGIS geodatabase formats, commonly used for Maine GIS data, carry default identifiers and attributes that are software generated and/or important for internal recordkeeping. These are listed here to avoid repetition for every layer, and may not be repeated in the attribute descriptions and definitions of each layer. Common software generated identifiers and attributes in Maine GIS data include: FID (feature identifier), Shape (feature geometry), OBJECTID and SHAPE_lengt. In addition, most GIS formats will carry fields for PERIMETER, AREA and/or LENGTH according to feature geometry. These fields are typically available by default, with the units based on coordinate system or projection units of GIS data. Most GIS software packages also provide a means to calculate these values. It is important to test any columns containing PERIMETER, AREA or LENGTH values before using them for analysis purposes. These important values can be carried from format to format and become out-dated. Verify that the values are correct. Also, in your GIS software, please view the properties of data layers for the map units used to calculate these fields, and for the units set for display purposes.

Entity and Attribute Overview

Each contour is coded with the elevation measured in units.

Entity and Attribute Detail Citation

Contact Organization

(MEGIS) Maine Office of Geographic Information Systems

Contact Person

GIS Coordinator

Contact Position

GIS Coordinator

Address Type

mailing address

Address

State House Station 174

City

Augusta

State or Province

Postal Code

04333-0174

Country

USA

Contact Voice Telephone

207 624-7700

Contact Facsimile Telephone

207 287-3842

Hours of Service

Monday through Friday 0800 - 1700 EST

Resource Description

http://megis.maine.gov/catalog/

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, is liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets.

Format Name

ESRI Shapefile

Format Version Number

ARC Version 9.x

Format Specification

ArcView Shapefile Format

Format Information Content

MEGIS has made all vector layers, in the Maine GIS Internet Data Catalog, available in ESRI's ArcView shapefile format. 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, ArcGIS, ArcExplorer. Shapefiles are a compatible data type for many other types of GIS software. Three files are fundamental to 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.

File Decompression Technique

Data available from this website is in .zip compressed format. WinZip is a Windows based, PKZip-compatible compression utility. You will need a program like this to extract the data.

Network Resource Name

http://megis.maine.gov/catalog/

[accinstr]

These data are available to Internet browsers for download from the Maine GIS Internet Data Catalog - http://megis.maine.gov/catalog/Data available from this website is in .zip compressed format. WinZip is a Windows based, PKZip-compatible compression utility. You will need a program like this to extract the data.If you are not already a GIS user, free software for viewing these files is available from Environmental Systems Research Institute, Inc. (ESRI) - www.esri.com

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.

Technical Prerequisites

If you are not already a GIS user, free software for viewing these files is available from Environmental Systems Research Institute, Inc. (ESRI) http://www.esri.com/

Beginning Date

20000101

Beginning Time

Unknown

Ending Date

Present

Ending Time

Unknown

Contact Organization

Maine Office of Geographic Information Systems

Contact Position

GIS Coordinator

Address Type

mailing address

Address

State House Station 174

City

Augusta

State or Province

Postal Code

04333-0174

Country

USA

Contact Voice Telephone

(207) 624-7700

Contact Facsimile Telephone

(207) 287-3842

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.

Format Name

ARCSDE

Format Version Number

ArcSDE 9.x

Format Information Content

Oracle 9i

[accinstr]

Please contact the Maine Office of GIS (MEGIS) for access instructions.

[smdistty]

Fees

Access is available through Maine's wide area network; WAN users may contact the Maine Office of Information Technology, Maine Office of Geographic Information Systems (MEGIS) for a login.

Metadata Reference Information

Metadata Date

20000701

Metadata Review Date

20100114

Metadata Future Review Date

Metadata Contact

Contact Organization	(MEGIS) Maine Office of Geographic Information Systems
Contact Person	GIS Coordinator
Contact Position	GIS Coordinator
Address Type	mailing address
Address	State House Station 174
City	Augusta
State or Province	ME
Postal Code	04333-0174
Country	USA
Contact Voice Telephone	207 624-7700
Contact Facsimile Telephone	207 287-3842
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 Access Constraints

None

Metadata Use Constraints

None