Administrative Services

Spot Elevation

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator:
Allegheny County Division of Computer Services Geographic Information Systems Group
Publication_Date: 2006
Title: Spot Elevation
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:
Spot Elevation data was created as a result of a county flyover in the spring of 2004. They were created from a DTM Feature Dataset, upgraded by Baker and T-3 to support National Mapping Accuracy Standards (NMAS). Spot Elevations are used to show additional elevation information. They are located in flat areas where contours may be sparse or spaced far apart, at road and railroad intersections, on the road centerline at the ends of bridges, on the road centerline over the center of culverts that have a span of five (5)-foot or greater, at the crest of all tops of hills, at saddles, within depressions and where the ground is visible in obscured areas.
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: -80.373199
East_Bounding_Coordinate: -79.671427
North_Bounding_Coordinate: 40.686763
South_Bounding_Coordinate: 40.181481
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:
Spot Elevation accuracy is such that 90% of all spot elevations are accurate to within 1/4th of the contour interval and 10% will be accurate to within one contour level.
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
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:
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
Source_Used_Citation_Abbreviation: County GIS Staff
Process_Time: 2004-2005
Process_Step:
Process_Description: Metadata was created

Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Entity point
Point_and_Vector_Object_Count: 99451
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: spotelev
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: UPDATE_YEA
Attribute:
Attribute_Label: X_COORDINA
Attribute:
Attribute_Label: FEATURECOD
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1410
Enumerated_Domain_Value_Definition: Spot Elevations
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide, March 1, 1993
Enumerated_Domain:
Enumerated_Domain_Value: 1420
Enumerated_Domain_Value_Definition: Water Elevations
Enumerated_Domain_Value_Definition_Source: Large Scale Database Quality Control Guide, March 1, 1993
Attribute:
Attribute_Label: Y_COORDINA

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 09:48:53 2007