Contours - 2 foot

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Office of the Chief Technology Officer
Publication_Date: 20091202
Title:
Contours - 2 foot
Geospatial_Data_Presentation_Form: vector digital data
Online_Linkage: \\OCTO-7M1HVH1\C$\12_10_2009_Shapefiles_KMZ\DCGIS_TopoLn.shp
Larger_Work_Citation:
Citation_Information:
Originator: DC GIS
Title:
DC Geographic Information System
Geospatial_Data_Presentation_Form: vector digital data
Description:
Abstract:
2 foot contours.  This dataset contains locations and attributes of 2-ft interval topography data, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies.  

In addition to the 2-ft contour data ancillary datasets containing an ESRI geodatabase of masspoints and breaklines and a TIN (Triangulated Irregular Network) have also been provided and are an integral part of this dataset.  All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters.  

METADATA CONTENT IS IN PROCESS OF VALIDATION AND SUBJECT TO CHANGE.
Purpose:
This data is used for the planning and management of Washington, D.C. by local government agencies.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20080528
Currentness_Reference:
ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -77.119436
East_Bounding_Coordinate: -76.909256
North_Bounding_Coordinate: 38.995919
South_Bounding_Coordinate: 38.803143
Data_Set_G-Polygon:
Data_Set_G-Polygon_Outer_G-Ring:
G-Ring_Point:
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: Topography
Theme_Keyword: breakline
Theme_Keyword: contour
Theme_Keyword: elevation
Place:
Place_Keyword: Washington, D.C.
Place_Keyword: District of Columbia
Place_Keyword: DC
Place_Keyword: DC GIS
Place_Keyword: DCGIS
Use_Constraints:
Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: GIS Data Coordinator
Contact_Organization: DC Office of the Chief Technology Officer (OCTO)
Contact_Address:
Address_Type: mailing and physical address
Address:
801 7th Street SW
City: Washington DC
Postal_Code: 20024
Country: USA
Contact_Voice_Telephone: (202) 727-5660
Contact_Electronic_Mail_Address: dcgis@dc.gov
Hours_of_Service: 8:30 am - 5:00 pm
Data_Set_Credit:
Office of the Chief Technology Officer
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.0.1770
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Contours were coded as either intermediate or index depending on the elevation attached to each contour.  The tiled contours are then processed along with additional data such as buildings so that indefinite or hidden contours can be properly coded.
Logical_Consistency_Report:
Validated by KCI Technologies, Inc. and OCTO.  Contours were checked for overlaps or dangles.  Any errors that may be flagged are corrected by a GIS technician.  Tiles of data are also checked to ensure that contour ties between tiles are spatially connected and have like attributes.  If any errors are found they are corrected by a GIS technician.  Contours are checked for proper connectivity and topology by using various ESRI tools.
Completeness_Report:
Data believed to be complete and accurate, subject to change.  Validated by responsible agency"
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Horizontal Accuracy of planimetric/topographic data is in accordance with ASPRS Class I Accuracy standards.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
This data has been tested in accordance with the NSSDA Spatial Data Standards.  Fifty-seven (57) checkpoints were used in the evaluation.  Checkpoints were derived from multiple sources including: 1) KCI surveyed independent checkpoints, 2) Checkpoints/GCPs used for a previous mapping program (14th street bridge), 3) Survey control withheld from the final aerial triangulation solution  All of these tests were based on a final Airborne GPS, AT, and DTM.  As a result the data has been found to have a vertical RMSE of 1.0ft.  At the 95% confidence level this is 2.0ft.  This data has been found to meet ASPRS Class 1.5 Accuracy Standards.   In comparison to National Map Accuracy Standards where 90% of the checkpoints should be within 1’ our findings indicate 86% of the well defined points are within 1’ and the remaining 93% are within 2’.  Any accuracy limitations were primarily impacted by flying height, image resolution, and lack of sidelap in specific areas which impacts the overall block adjustment.

The contours are good for planning purposes but should not be used for precise engineering and survey work at the ASPRS class 1 accuracy standard level.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: Office of the Chief Technology Officer
Publication_Date: 20080528
Title:
Aerial Photography and AT solution
Online_Linkage: http://dcgis.dc.gov
Type_of_Source_Media: aerial photography
Source_Citation_Abbreviation:
2008 DC aerial photography and AT solution
Source_Contribution:
attributes and location
Process_Step:
Process_Description:
A photogrammetrically compiled DTM of masspoints and breaklines was compiled using ZI Imaging softcopy photogrammetric workstations.  The completed DTM dataset, having already been checked for accuracy, was run through the Sanborn's APS proprietary software in order to generate contours.    All DTM data is translated into APS format. 

Tiles of overlapping DTM data are extracted in order to make contour processing more efficient.  The overlapping of DTM data allows for contour generation to be more precise at tile edges.  Contours were generated at a 2' interval for each tile of data.  During the generation process, elevation attributes were created on each contour. Any enclosed contour that was less than 30 square meters in area was automatically deleted.  

Contours were then coded as either intermediate or index depending on the elevation attached to each contour.  Contours are also gently smoothed and/or filtered in order to give a more aesthetically pleasing look.  

As part of Sanborn's quality process, the contours were checked for overlaps or dangles.  Any errors that may be flagged are corrected by a GIS technician.    The tiled contours are then processed along with additional data such as buildings so that indefinite or hidden contours can be properly coded.  

At this point, tiles of data are also checked to ensure that contour ties between tiles are spatially connected and have like attributes.  If any errors are found, they are corrected by a GIS technician.  

Once the contours are deemed complete, they are translated out of APS format into an ESRI geodatabase as a single feature class.  The contours are checked again for proper connectivity and topology by using various ESRI topology and visual tools. 

Once these checks are finished, the data is considered complete.  DTM data also was exported to a ESRI TIN prior to delivery.  Data was delivered to KCI for visual inspection and corrections were ideintified and data was reprocessed and redelivered as appropriate.
Source_Used_Citation_Abbreviation:
C:\OCTOGIS\Data\Metadata\TemplateDCStat
Process_Date: 20090901
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Shawn Benham
Contact_Organization: Sanborn Map Company
Contact_Position: Project Manager
Contact_Address:
Address_Type: mailing and physical address
Address:
1935 Jamboree Drive Suite 100
City: Colorado Springs
State_or_Province: Colorado
Postal_Code: 80920
Country: USA
Contact_Voice_Telephone: (719) 502-1296
Contact_Electronic_Mail_Address: sbenham@sanborn.com
Hours_of_Service: 9am - 5pm
Process_Step:
Process_Description:
Metadata imported.
Source_Used_Citation_Abbreviation:
C:\temp\metadata.xml
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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: 0
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1983
State_Plane_Coordinate_System:
SPCS_Zone_Identifier: 1900
Lambert_Conformal_Conic:
Standard_Parallel: 38.300000
Standard_Parallel: 39.450000
Longitude_of_Central_Meridian: -77.000000
Latitude_of_Projection_Origin: 37.666667
False_Easting: 400000.000000
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.000000
Ordinate_Resolution: 0.000000
Planar_Distance_Units: meters
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: 0.000100
Altitude_Distance_Units: feet
Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
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Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: DCGIS_TopoLn
Attribute:
Attribute_Label: Shape
Attribute_Definition:
Feature geometry
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Coordinates defining the features.
Attribute:
Attribute_Label: SHAPE
Attribute_Definition:
Feature geometry.
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Coordinates defining the features.
Attribute:
Attribute_Label: GIS_ID
Attribute_Definition:
OCTO GIS Internal Identifier
Attribute:
Attribute_Label: FEATURECOD
Attribute:
Attribute_Label: DESCRIPTIO
Attribute:
Attribute_Label: ELEVATION
Attribute_Definition:
Feature geometry.
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Coordinates defining the features.
Attribute:
Attribute_Label: CAPTUREYEA
Attribute:
Attribute_Label: CAPTUREACT
Attribute:
Attribute_Label: SHAPE_LEN
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: DC Office of the Chief Technology Officer
Contact_Person: GIS Data Coordinator
Contact_Address:
Address_Type: mailing and physical address
Address:
441 4th St NW, Suite 930 South
City: Washington
State_or_Province: DC
Postal_Code: 20001
Country: USA
Contact_Facsimile_Telephone: (202) 727-5660
Contact_Electronic_Mail_Address: dcgis@dc.gov
Hours_of_Service: 8:30 am - 5:30 pm
Resource_Description: Downloadable Data
Distribution_Liability:
Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Transfer_Size: 0.000
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Ordering_Instructions:
Most DC GIS datasets can be downloaded from "http://dcgis.dc.gov" on the data center page.  Orders can also be made by contacting OCTO GIS at "dcgis@dc.gov", especially for datasets not available for download.
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Metadata_Reference_Information:
Metadata_Date: 20091214
Metadata_Review_Date: 20091202
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: D.C. Office of the Chief Technology Officer
Contact_Person: GIS Data Coordinator
Contact_Address:
Address_Type: mailing and physical address
Address:
441 4th St NW, Suite 930 South
City: Washington
State_or_Province: DC
Postal_Code: 20001
Country: USA
Contact_Facsimile_Telephone: (202) 727-5660
Contact_Electronic_Mail_Address: dcgis@dc.gov
Hours_of_Service: 8:30 am - 5 pm
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
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