Impervious Surfaces of Loudoun County, VA (2012)

Metadata also available as

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator:
Loudoun County, VA, Department of Building and Development, GIS Administration
Publication_Date: 20120320
Title: Impervious Surfaces of Loudoun County, VA (2012)
Geospatial_Data_Presentation_Form: vector digital data
Online_Linkage: see distribution information
Description:
Abstract:
The Impervious Surface Dataset is derived from Loudoun County Base Map Data, which is captured and maintained from aerial imagery through stereocompilation and photogrammetry. This dataset is comprised of building footprints, roads, driveways, sidewalks, trails, parking lots, water, quarries, pools, and recreational courts. We anticipate this to be an accurate representation of water and the anthropogenic impervious surfaces present. This dataset is meant to be an approximation of the impervious surfaces present on the ground, but note that many external factors affect this such as the varying permeability of the naturally occurring soils.In March 2012, a new source of Impervious Surfaces was included in the dataset with the creation of a new Sidewalk & Trails data layer. This source includes all sidewalks and trails,as of 2008, as an impervious surface.
Purpose: The dataset was developed as an environmental planning tool.
Supplemental_Information:
Data are stored in the corporate ArcSDE Geodatabase as a polygon feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN (vertical datum, if applicable, NAVD88), US Survey foot units.
Status:
Progress: Complete
Maintenance_and_Update_Frequency: Annually
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -77.964580
East_Bounding_Coordinate: -77.313965
North_Bounding_Coordinate: 39.330035
South_Bounding_Coordinate: 38.836941
Keywords:
Theme:
Theme_Keyword_Thesaurus: none: Employee generated
Theme_Keyword: imperviousness
Theme_Keyword: runoff
Theme_Keyword: impermeable
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: environment
Place:
Place_Keyword_Thesaurus: none: Employee generated
Place_Keyword: Loudoun
Place_Keyword: Virginia
Place_Keyword: County
Access_Constraints: None
Use_Constraints:
These data were generated for use by Loudoun County and are available to the public. These data are intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, Building & Development
Contact_Position: GIS Administration
Contact_Address:
Address_Type: mailing and physical
Address: MS 60A
Address: 1 Harrison Street SE, 2nd floor
City: Leesburg
State_or_Province: VA
Postal_Code: 20175
Country: US
Contact_Voice_Telephone: (703)777-0397
Contact_Facsimile_Telephone: (703)771-5522
Contact_Electronic_Mail_Address: bad@loudoun.gov
Hours_of_Service: 8:00-5:00 EST, M-F
Data_Set_Credit: Loudoun County, VA
Native_Data_Set_Environment:
Microsoft Windows Server 2008 Version 6.0 (Build 6002) Service Pack 2; ESRI ArcGIS 10.0.5.4400
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Retention of attribute accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class coversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have, on a record by record basis, identical attribution when comparing all concatenated fields to all the user-defined attribution.
Logical_Consistency_Report: Topologically clean
Completeness_Report:
Features may have been eliminated or generalized due to scale and intended use. To assist Loudoun County, Virginia in the maintenance of the data, please provide any information concerning discovered errors, omissions, or other discrepancies found in the data.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Retention of coordinate accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class conversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have the same record total, and on a record by record basis, area, perimeter, and length differential of less than +/- 0.5%.
Lineage:
Process_Step:
Process_Description:
The dataset creation for this layer was performed using ArcGIS' Model Builder in a step by step process. The CreatePersonalGDB command was first used to create Personal Geodatabase for layer development. Next,the FeatureClassToGeodatabase command was used to export the Buildings, RoadCasing, Water, and Misc Polygons into the Geodatabase. Then the MakeFeatureLayer command was applied to the Buildings, RoadCasing, and Water data. The Select Layer By Attribute command was then used to select types 1, 4, and 10 from the Water layer. The Make FeatureLayer command was then applied to the Misc Polygon layer and the Select Layer By Attribute command used to select only types 1, 2, and 7 from the layer. The CreateFeatureClass command was used to create the Impervious Surface layer in the new Geodatabase. The Make Feature Layer command was then applied to the Feature Class and the Append command used to combine the Buildings, Road Casing, Water, and Misc Polygon layer into the Impervious Surface Layer.
Process_Step:
Process_Description:
The following is a complete list of features that were included in the compilation of the Impervious Surfaces dataset. Definition queries were utilized for those data sources in which only a subset of their feature types were included. For more detailed information regarding the individual feature types, please contact Loudoun County B&D, GIS Administration. Feature Type, Data Source, Definition Query Building, Building, BL_TYPE = 1 Ruins or Under Construction, Building, BL_TYPE = 2 Pools (swimming pools or settling ponds), Miscellaneous Polygons, MI_TYPE = 1 Impervious Recreational Courts, Miscellaneous Polygons, MI_TYPE = 2 Quarry, Miscellaneous Polygons, MI_TYPE = 7 Road, Road Casings, RD_TYPE = 1 Parking Lots, Road Casings, RD_TYPE = 2 Driveways, Road Casings, RD_TYPE = 3 Airport Runways, Road Casings, RD_TYPE = 4 W&OD Trail, Road Casings, RD_TYPE = 8 Bridge Deck or Overpass, Road Casings, RD_TYPE = 9 Double Line Stream, Water, WA_TYPE = 1 Lake or Pond, Water, WA_TYPE = 4 Potomac River, Water, WA_TYPE = 10
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, Building & Development
Contact_Position: GIS Administration
Process_Step:
Process_Description:
This layer was updated in correlation with the Office of Mapping and Geographic Information's (OMAGI) 2008 Basemap update. All of the features that are used to compile the Impervious Surfaces dataset are obtained from selected Basemap layers. Two new attribute fields were also added to this layer to provide for further classification and symbolization of data based on a feature's data source: IM_SOURCE & IM_TYPE.
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, Building & Development
Contact_Position: GIS Administration
Process_Step:
Process_Description:
This layer was updated in correlation with the Office of Mapping and Geographic Information's (OMAGI) 2009 Basemap update. All of the features that are used to compile the Impervious Surfaces dataset are obtained from selected Basemap layers.
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, Building & Development
Contact_Position: GIS Administration
Process_Step:
Process_Description:
The data layer was updated with a new Impervious Surface feature class Source: Sidewalks & Trails. This source includes all sidewalks and trails as an impervious surface.
Process_Date: 20120312
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
Point_and_Vector_Object_Count: 249043
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: Lambert Conformal Conic
Lambert_Conformal_Conic:
Standard_Parallel: 38.03333333333333
Standard_Parallel: 39.2
Longitude_of_Central_Meridian: -78.5
Latitude_of_Projection_Origin: 37.66666666666666
False_Easting: 11482916.66666666
False_Northing: 6561666.666666666
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.00020833333333333288
Ordinate_Resolution: 0.00020833333333333288
Planar_Distance_Units:
Geodetic_Model:
Horizontal_Datum_Name: D North American 1983 HARN
Ellipsoid_Name: GRS 1980
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257222101
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: GISDBB.GISBROW.IMPERVIOUS_SURFACES_POLY
Attribute:
Attribute_Label: OBJECTID
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: IM_SOURCE
Attribute_Definition: Data source (feature class) of impervious surface feature
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: BLDG
Enumerated_Domain_Value_Definition: Buildings feature class
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: MISCPOLY
Enumerated_Domain_Value_Definition: Miscellaneous Polygons feature class
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: RDCASING
Enumerated_Domain_Value_Definition: Road Casings feature class
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: WATER
Enumerated_Domain_Value_Definition: Water Bodies feature class
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: SWALK_TRAIL
Enumerated_Domain_Value_Definition: All sidewalks and trails feature class
Attribute:
Attribute_Label: IM_TYPE
Attribute_Definition: Type value(s) of each invidual Source feature class
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: See Overview Description for Data Dictionary of types
Attribute:
Attribute_Label: SHAPE
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: DB2GSE.ST_Area(SHAPE)
Attribute_Definition: Area of feature in internal units squared.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Positive real numbers that are automatically generated.
Attribute:
Attribute_Label: DB2GSE.SdeLength(SHAPE)
Attribute_Definition: Perimeter of feature in internal units squared.
Attribute_Domain_Values:
Unrepresentable_Domain: Positive real numbers that are automatically generated.
Overview_Description:
Entity_and_Attribute_Overview: IM_TYPE: Type value(s) of each invidual Source feature class
Entity_and_Attribute_Detail_Citation:
BLDG: 1: Building 2: Ruins or Under Construction
MISCPOLY 1: Pool 2: Impervious Recreational Courts 7: Quarry
RDCASING: 1: Road 2: Parking Lot 3: Driveway 4: Airport Runway 8: W&OD Trail 9: Bridge Deck or Overpass
WATER: 1: Double Line Stream 4: Lake or Pond 10: Potomac River
SWALK_TRAIL 5: All sidewalks and trails
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: Public Information Counter
Contact_Address:
Address_Type: mailing and physical
Address: MS 65
Address: 1 Harrison Street S.E., 2nd floor
City: Leesburg
State_or_Province: VA
Postal_Code: 20175
Country: US
Contact_Voice_Telephone: (703)771-5778
Contact_Facsimile_Telephone: (703)771-5075
Contact_Electronic_Mail_Address: mapping@loudoun.gov
Hours_of_Service: 8:00-4:30 EST, M-F
Distribution_Liability: See access and use constraints information.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: GDB
Format_Specification: ESRI Personal Geodatabase Feature Class
Digital_Transfer_Option:
Offline_Option:
Offline_Media: dvd
Offline_Option:
Offline_Media: dvd
Offline_Option:
Offline_Media: dvd
Fees:
Loudoun County distributes spatial data in ArcGIS database or shapefile & DXF format for the cost of reproduction. Countywide spatial datasets may be purchased for $22 per DVD for up to 4.5 GB of data. There is a $100 surcharge to purchase countywide topography, and a $3 charge if the item is to be mailed. If the customer wants the data in DXF format and/or would like OMAGI to custom select specific geographic areas of the County, there is an additional $7 per 15 minute increment labor charge. Select aerial imagery is also available
Ordering_Instructions:
Size limit: 4.5 GB. Visit our website at: <http://www.loudoun.gov/omagi>, click on "Loudoun County Mapping Documents & Order Forms." The "Forms" directory will lead you to custom & standard (countywide) data order forms. Hardcopy maps may also be available; please contact the Mapping Office Public Information Counter for more information regarding all data requests.
Metadata_Reference_Information:
Metadata_Date: 20121129
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: metadata specialist
Contact_Address:
Address_Type: mailing and physical
Address: MS 65
Address: 1 Harrison Street S.E., 2nd floor
City: Leesburg
State_or_Province: VA
Postal_Code: 20175
Contact_Voice_Telephone: (703)771-5778
Contact_Facsimile_Telephone: (703)771-5075
Contact_Electronic_Mail_Address: mapping@loudoun.gov
Hours_of_Service: 8:00-4:30 EST, M-F
Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Use_Constraints:
This metadata reflects the source Geodatabase format and specific elements may not apply if your data is exported to SHP or DXF products. User must be aware that changes to data schema occur during data export that may not be reflected in this metadata, which represents Loudoun County's corporate geodatabase. Acknowledgement of Loudoun County would be appreciated in the use of this metadata.
Generated by mp version 2.9.6 on Thu Nov 29 09:06:49 2012