Administrative Services

Contours

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator:
Allegheny County Division of Computer Services Geographic Information Systems Group
Publication_Date: 2006
Title: Contours
Geospatial_Data_Presentation_Form: vector digital data
Series_Information:
Series_Name: Base Data
Publication_Information:
Publication_Place: Pittsburgh, PA
Publisher:
Allegheny County Division of Computer Services Geographic Information Systems Group
Description:
Abstract:
Contour data was created as a result of a county flyover in the spring of 2004. Contours were created from a DTM Feature Dataset, upgraded by Baker and T-3 to support National Mapping Accuracy Standards (NMAS) for contours . Intermediate Contours are contours spaced at 5 foot intervals. Depression Contours are contours showing the edges and slope in a depression at 5 foot intervals. Contours are coded separately for delineation between depression and intermediate contours.
Purpose:
Data was developed as part of the continuing effort to establish and maintain large scale base data in support of the Geographic Information System in Allegheny County.
Supplemental_Information:
Data meets or exceeds map accuracy standards in effect during the spring of 2004. Digital Globe and Michael Baker Corporation held a contract with Allegheny County to fly the County to produce digital orthophotography and to update planimetric base data for the approximate 730 square miles of Allegheny County. Subcontractors for the project included: T3 Global Strategies, Sweet Solutions and Keystone Aerial Surveys. Photography was produced at a scale of 1"=1600'. Mapping was stereo digitized at a scale of 1"=200'. Digital Orthophotos were included as a deliverable.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: Spring 2004
Currentness_Reference: publication date
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -80.373621
East_Bounding_Coordinate: -79.670684
North_Bounding_Coordinate: 40.687004
South_Bounding_Coordinate: 40.180685
Keywords:
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: elevation
Theme_Keyword: imageryBaseMapsEarthCover
Place:
Place_Keyword: Allegheny County
Place_Keyword: Pittsburgh
Place_Keyword: Southwest Pennsylvania
Access_Constraints: Call for Details
Use_Constraints:
All parties acknowledge that the data is for informational purposes only. The existing digital data is shipped as is and there is no guarantee as to its completeness or accuracy. Allegheny County Division of Computer Services Geographic Information Systems Group is not responsible for any reliance upon said data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Allegheny County Division of Computer Services Geographic Information Systems Group
Contact_Position: GIS Manager
Contact_Voice_Telephone: 412 350-4774
Contact_Facsimile_Telephone: 412 350-4754
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.1.0.722
Cross_Reference:
Citation_Information:
Originator:
Allegheny County Division of Computer Services Geographic Information Systems Group

Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Contours accurately depict and reflect the crown and cross slope of paved areas including roads and paved ditches and accurately depict all drainage ways. Ninety percent of all elevations from contours will have an accuracy, with respect to true elevation, of within of one half of the contour interval. Ten percent of elevations will not be in error by more than one contour interval. The contours are created from the DTM Feature Dataset. Contours are divided into two (2) main groups; Index Contours and Intermediate Contours. Every fifth contour is classified as an Index Contour and has an elevation interval of a multiple of 25'. Index Contours will be labeled with annotation displaying the elevation of the contour. Contours will not be broken for the placement of the contour label. The contour will be drawn through the label. All other contours are Intermediate Contours.

Where appropriate, contours are assigned an additional classification of Hidden, Obscure and Depression. Contours that are created and fall within a building or under a bridge, as a result of creating continuous contours, are coded as Hidden. Obscure Contours are contours that are in an area where the ground is obscured from view on the aerial photography. Obscure Contours will also fall within an Obscure Area Boundary. The Obscure Contours should not be considered accurate as they only give a general representation of the surface of the earth. Depression Contours are closed contours that form a sunken area (depression). Some depressions can cover a large area of land and may not be seen as a depression at a large scale.

The contours were created using Bentely SelectCAD software and the following settings: " Import Surface o Thin Surface: Off o Breaklines " Maximum Segment Length: Off " Point Density:Off o Mass Points " Maximum Segment Length:Off " Triangulate Surface o Maximum Length: 0.0 o Filter Tolerance: 0.0 " View Contours: o Display As Linestring o Minimum Area: 500.0 o Clip Contours on Steep Slopes: No o Smooth: On

Logical_Consistency_Report:
Data was subject to QA/QC process at the time it was created. Data was created as part of the County's base layer(s) update in the spring of 2004.
Completeness_Report: Data was created for all of Allegheny County.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
All horizontal control is to NGS Second Order Class I accuracy or better and photo control points are reported on the North American Datum (NAD) 1983 U.S. Survey Feet. The aerial photography was captured at a negative scale of 1" = 1,600' and is sufficient to produce mapping at 1" = 200' that conforms to National Mapping Accuracy Standards (NMAS).
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: +/- 5 feet
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
All final elevations are referenced to North American Vertical Datum (NAVD) 1988. Orthometric heights utilize GEOID 99. The network adheres to the Federal Geodetic Control Committee Standards (FGCS) guidelines and the final constrained adjustments were made with StarNet Least Squares Adjustment program and are acceptable by the National Geodetic Survey (NGS).
Quantitative_Vertical_Positional_Accuracy_Assessment:
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:
Allegheny County Division of Computer Services Geographic Information Systems Group
Publication_Date: 2006
Title: Base Data 2004 Flyover
Series_Information:
Series_Name: 2004 Flyover
Publication_Information:
Publication_Place: Allegheny County
Publisher:
Allegheny County Division of Computer Services Geographic Information Systems Group
Other_Citation_Details: All contours are continuous.
Source_Scale_Denominator: 200'
Type_of_Source_Media: CD-ROM
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2004
Ending_Date: 2006
Source_Currentness_Reference: publication date
Source_Contribution:
Digital Globe and Michael Baker Corporation held a contract with Allegheny County to fly the County to produce digital orthophotography and to update planimetric base data for Allegheny County. Subcontractors for the project included: T3 Global Strategies, Sweet Solutions and Keystone Aerial Surveys.
Process_Step:
Process_Description:
Using existing County DTM files referenced to NGVD 1929 Vertical Datum, an average countywide elevation difference between the cuerrent data and the NAVD 1988 was determined. Existing DTM was shifted the averaged amount, enabling it to be updated to meet the NMAS (National Mapping Accuracy Standards) vertical accuracy requirements for 5' contour mapping.Corresponding MicroStation graphics files in stereo model units were generated. With the use of softcopy stereo workstations, each MicroStation model file of existing data was super-imposed on the corresponding stereo imagery created during this fly-over. Break lines, mass points and breaklines were updated as needed. Breaklines were captured at all slope breaks such as ridge and valley lines, roads and railroads. All hydrographic features were captured as breaklines and used in the triangulation process to ensure contour turnbacks that fit the water features. The same rules were applied to new compilation and updates.
Process_Date: 2004
Process_Step:
Process_Description:
The normal mass point density of 20-25 times the contour interval may have been adjusted depending on the type of terrain being mapped. Uneven terrain requires a denser spacing than flat or gently rolling terrain. In addition spot elevations were digitized in the DTM file at the following locations: Road/railroad intersections On the road centerline at the abutment and center of bridges and similar structures On road centerlines over major culverts At the crest of closed contours At the lowest point of all closed depression contours, significant saddles, cuts and depressions At the intersection point of tributaries with the center of the main channel In areas of dense vegetation where the ground is visible
Process_Step:
Process_Description:
Following the completion of the DTM data collection, check contours were developed by the stereo operator, enabling them to be viewed with the stereo model. InRoads Software loads the features from the DTM and generates a three dimensional contour file. Spot elevations could then be added at peaks and saddles, as well as additional breaklines and mass points, if needed. When the stereo operator was satisfied with the DTM, files were provided to map editors for final contour generation and editing.
Process_Step:
Process_Description:
Tiles were created for the contour data based on the Allegheny County tiling scheme. As a sufficient backlog of completed models were generated, the DTM model files were combined for the tile, a TTN created and 3D contours generated. Contours were generated at five (5) foot intervals with a twenty-five (25) foot index. Index contours were generated at a heavier weight and were automatically labeled. All contours are continuous. They were processed with building data if available and segments within buildings and under bridges are coded as hidden. Each contour is tagged with its elevation and attributed accordingly. Before submitting tiles for translation to ArcInfo coverages, the following automated data validation processes were performed: GraphicsVerify; LineCheck; EdgeMatch.
Process_Step:
Process_Description:
ArcInfo coverages were created from MicroStation design files using in-house developed translation software. Allegheny County's Data Dictionary was used as the base upon which the ArcInfo structure was designed. Each coverage was subjected to review and inspection using ArcMap. Any revisions or corrections were performed in the MicroStation design files. After any corrections were performed, the files were re-translated, re-plotted and re-checked to confirm correct translations. ArcMap was then used to visually check the planimetric data against the digital orthophoto on a tile basis. The final QC step was to merge all tiles to verify the edgematch. Validation was done using MRF. The ESRI tool LOADDATA was used to convert coverages to the final deliverable format, the geodatabase.
Source_Produced_Citation_Abbreviation: Michael Baker Engineers
Process_Step:
Process_Description: Data was loaded into SDE
Process_Step:
Process_Description: Metadata imported.
Source_Used_Citation_Abbreviation: C:\DOCUME~1\t094246\LOCALS~1\Temp\xml780.tmp

Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: String
Point_and_Vector_Object_Count: 1464242
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Point
Point_and_Vector_Object_Count: 1756
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Label point
Point_and_Vector_Object_Count: 30990

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: Lambert Conformal Conic
Lambert_Conformal_Conic:
Standard_Parallel: 39.933333
Standard_Parallel: 40.966667
Longitude_of_Central_Meridian: -77.750000
Latitude_of_Projection_Origin: 39.333333
False_Easting: 1968500.000000
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.000512
Ordinate_Resolution: 0.000512
Planar_Distance_Units: survey feet
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.000000
Denominator_of_Flattening_Ratio: 298.257222
Vertical_Coordinate_System_Definition:
Altitude_System_Definition:
Altitude_Datum_Name: North American Vertical Datum of 1988
Altitude_Resolution: 0.000001
Altitude_Distance_Units: feet
Altitude_Encoding_Method:
Explicit elevation coordinate included with horizontal coordinates

Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: contours
Attribute:
Attribute_Label: FID
Attribute_Definition: Internal feature number.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: ELEVATION
Attribute:
Attribute_Label: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: FEATURECOD
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1310
Enumerated_Domain_Value_Definition:
Intermediate Contours: Contours at a 5' interval. Elevation above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1311
Enumerated_Domain_Value_Definition:
Hidden Intermediate Contours: Breaks in Contour Lines for annotation or through structures. Contours at a 5' interval. Elevation above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1320
Enumerated_Domain_Value_Definition:
Intermediate Depression Contours: Depression contours at a 5' interval. Elevation above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1321
Enumerated_Domain_Value_Definition:
Breaks in Contour Lines for annotation or through structures; Depression contours at a 5' interval. Elevation above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1330
Enumerated_Domain_Value_Definition:
Intermediate Dense Tree Contours: Contours at a 5' interval in an area covered by natural vegetation. Elevation above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1331
Enumerated_Domain_Value_Definition:
Hidden Intermediate Dense Tree Contours: Contours at a 5' interval in an area covered by natural vegetation. Elevation above Mean Sea Level (MSL). Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1340
Enumerated_Domain_Value_Definition:
Index Contours: Contours at the 25' Interval, annotated with elevations from Mean Sea Level (MSL) elevations above MSL.
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1341
Enumerated_Domain_Value_Definition:
Hidden Index Contours: Contours at the 25' Interval, annotated with elevations from MSL, elevations above Mean Sea Level (MSL) Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1350
Enumerated_Domain_Value_Definition:
Index Depression Contours: Depression Contours at the 25' Interval, annotated with elevations from Mean Sea Level (MSL) elevations above MSL.
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1351
Enumerated_Domain_Value_Definition:
Hidden Index Depression Contours: Depression Contours at the 25' Interval, annotated with elevations from MSL, elevations above Mean Sea Level (MSL) Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1360
Enumerated_Domain_Value_Definition:
Index Dense Tree Depression Contours: Depression Contours at the 25' Interval in areas covered by natural vegetation, annotated with elevations from MSL, elevations above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1361
Enumerated_Domain_Value_Definition:
Hidden Index Dense Tree Depression Contours: Depression Contours at the 25' Interval in areas covered by natural vegetation, annotated with elevations from MSL, elevations above Mean Sea Level (MSL) Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1370
Enumerated_Domain_Value_Definition:
Intermediate Depression Dense Tree Contours: Depression Contours at the 5' Interval in areas covered by natural vegetation, elevations above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1371
Enumerated_Domain_Value_Definition:
Hidden Intermediate Depression Dense Tree Contours: Depression Contours at the 5' Interval in areas covered by natural vegetation, elevations above Mean Sea Level (MSL) Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1380
Enumerated_Domain_Value_Definition:
Index Dense Tree Contours: Contours at the 25' Interval in areas covered by natural vegetation annotated with elevations from MSL, elevations above Mean Sea Level (MSL)
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1381
Enumerated_Domain_Value_Definition:
Hidden Index Dense Tree Contours: Contours at the 25' Interval in areas covered by natural vegetation annotated with elevations from MSL, elevations above Mean Sea Level (MSL) Breaks in Contour Lines for annotation or through structures
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide March 1, 1993
Attribute:
Attribute_Label: UPDATE_YEA
Attribute:
Attribute_Label: OBJECTID

Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Allegheny County Division of Computer Services Geographic Information Systems Group
Contact_Position: GIS Manager
Contact_Address:
Address_Type: mailing and physical address
Address: 621 County Office Building
Address: 542 Forbes Avenue
City: Pittsburgh
State_or_Province: PA
Postal_Code: 15219-2952
Country: USA
Contact_Voice_Telephone: 412 350-4774
Contact_Facsimile_Telephone: 412 350-4754
Resource_Description: Call for details.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Transfer_Size: 66.284
Ordering_Instructions: Call for Details

Metadata_Reference_Information:
Metadata_Date: 20071101
Metadata_Review_Date: August, 2006
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Allegheny County Division of Computer Services Geographic Information Systems Group
Contact_Position: System Supervisor,GIS
Contact_Address:
Address_Type: mailing and physical address
Address: 621 County Office Building
Address: 524 Forbes Avenue
City: Pittsburgh
State_or_Province: PA
Postal_Code: 15219-2952
Country: USA
Contact_Voice_Telephone: 412 350-4774
Contact_Facsimile_Telephone: 412 350-4754
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Extensions:
Online_Linkage:<http://www.esri.com/metadata/esriprof80.html>
Profile_Name: ESRI Metadata Profile

Generated by mp version 2.8.6 on Thu Nov 01 09:58:55 2007