Water Bodies of Loudoun County, VA (2020)

Metadata also available as

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator:
Loudoun County, Virginia, Office of Mapping and Geographic Information (OMAGI)
Publication_Date: 20210427
Title: Water Bodies of Loudoun County, VA (2020)
Geospatial_Data_Presentation_Form: vector digital data
Description:
Abstract:
Water Bodies, including surface elevation, are a base map data layer derived by automated processes and processed for cartographic representation at 1:2400 scale. The polygon features represent the ponds, reservoirs, stormwater impoundments, marshes, and major creeks and rivers found on the County's base map as seen from above and are mapped to National Map Accuracy Standards (NMAS).
Purpose:
Water Bodies are used for water supply planning, the administration of related zoning restrictions, and to locate water supplies in rural areas for fighting fires.
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, NAVD88, US Survey foot units.
OMAGI updates all base map data via photogrammetric process, using aerial imagery that is flown yearly. A different portion of the county is updated each year with the base map maintenance services contract, depending upon development patterns and update funding. The field “UPD_DATE” indicates the date a feature was last re-mapped. For a map of the most recent reviews and updates within the county, please click on https://arcg.is/0Tm9PW0
Status:
Progress: Complete
Maintenance_and_Update_Frequency: Annually
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -77.947486
East_Bounding_Coordinate: -77.313965
North_Bounding_Coordinate: 39.329955
South_Bounding_Coordinate: 38.836941
Keywords:
Theme:
Theme_Keyword_Thesaurus: none; employee generated
Theme_Keyword: reservoir
Theme_Keyword: impoundment
Theme_Keyword: creek
Theme_Keyword: water body
Theme_Keyword: pond
Theme_Keyword: water
Theme_Keyword: stormwater
Theme_Keyword: stream
Theme_Keyword: hydrology
Theme_Keyword: river
Theme_Keyword: lake
Theme_Keyword: water surface level
Theme_Keyword: marsh
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: biota
Theme_Keyword: inlandWaters
Place:
Place_Keyword_Thesaurus: none; employee generated
Place_Keyword: County
Place_Keyword: Sleeter Lake
Place_Keyword: Loudoun
Place_Keyword: Bull Run
Place_Keyword: Broad Run
Place_Keyword: Catoctin Creek
Place_Keyword: Beaverdam Creek
Place_Keyword: Potomac River
Place_Keyword: Virginia
Place_Keyword: Sugarland Run
Place_Keyword: Goose Creek
Place_Keyword: Beaverdam Reservoir
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, (OMAGI
Contact_Position: Base Map Coordinator
Contact_Address:
Address_Type: mailing and physical
Address: MS 65
Address: 1 Harrison Street SE, 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
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:
Water Bodies have undergone extensive Quality Assurance procedures to ensure feature attribution is consistent with the data dictionary and adheres to a logical relationship with neighboring features and layers.
Quantitative_Attribute_Accuracy_Assessment:
Attribute_Accuracy_Value: >90% attribute accuracy exists
Attribute_Accuracy_Explanation:
27 separate block study areas underwent QA/QC comparison with the source orthophoto and overlaying base map layers. Greater than 90% of all features in each block achieve correct TYPE attribution. OMAGI compiled a separate PGDB for known attribute errors above 90% threshold.
Logical_Consistency_Report: Topologically clean
Completeness_Report:
Base Map features have been updated from different sources and in different years. Although the entire county was originally mapped, users should be cautious and aware that any particular area of interest may not be absolutely current and up to date. A generalized map of update years can be located at the OMAGI's webpage. The next anticipated update shall occur using 2016 imagery.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Accuracy Assessments have been computed according to The National Standard for Spatial Data Accuracy (NSSDA). NSSDA implements a statistical and testing methodology for estimating the positional accuracy of points on maps and in digital geospatial data with respect to georeferenced ground positions of higher accuracy. Accuracy is reported in ground distances at the 95% confidence level. Accuracy reported at the 95% confidence level means that 95% of the positions in the dataset will have an error with respect to true ground position that is equal to or smaller than the reported accuracy value. Data has been tested and meets NSSDA and ASPRS accuracy requirements for 1:2400 scale maps.
Vertical_Positional_Accuracy:
Quantitative_Vertical_Positional_Accuracy_Assessment:
Vertical_Positional_Accuracy_Value: RMSE (Z or Elev.)= 1.24; Tested 2.43 US Survey feet
Vertical_Positional_Accuracy_Explanation:
Measured at 95% confidence level, any points measured will be within 2.43 US Survey feet in the vertital domain.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20020128
Title: Base Map Maintenance Services Contract, QQ-00986, Phase I
Geospatial_Data_Presentation_Form: remote-sensing image
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, Phase I
Source_Contribution:
Captured Western 2/3 of County generally located north of Leesburg, west of Rt. 621, Evergreen Mills Rd, and south of Braddock Rd.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Loudoun County, VA, OMAGI
Publication_Date: 20040308
Title: Base Map Maintenance Service Contract, QQ-00986, Phase II
Geospatial_Data_Presentation_Form: remote-sensing image
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Service Contract, QQ-00986, Phase II
Source_Contribution:
Captured Eastern 1/3 of County generally located to include Leesburg, east of Rt. 621, Evergreen Mills Rd, and north of Braddock Rd.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Loudoun County, VA, OMAGI
Publication_Date: 20050307
Title: Base Map Maintenance Services Contract, QQ-00986, Phase III
Geospatial_Data_Presentation_Form: remote-sensing image
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, Phase III
Source_Contribution:
Captured photogrammetric stereo models covering highest development areas in the original Phase I region and including Leesburg.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20070305
Title: Base Map Maintenance Services Contract, QQ-00986, Phase IV
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, Phase IV
Source_Contribution:
Captured and updated photogrammetric stereo models covering highest development areas in the original Phase II region.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20080303
Title: Base Map Maintenance Services Contract, QQ-00986, 2008
Geospatial_Data_Presentation_Form: remote-sensing image
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, 2008
Source_Contribution:
Captured and updated photogrammetric stereo models covering highest development areas in the north eastern region.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Loudoun County, VA, OMAGI
Publication_Date: 20090302
Title: Base Map Maintenance Services Contract, QQ-00986, 2008
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, 2008
Source_Contribution:
Captured and updated photogrammetric stereo models covering highest development areas in the western region.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20130514
Title: Base Map Maintenance Services Contract, QQ-01407, 2012
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01407, 2012
Source_Contribution:
Captured and updated photogrammetric stereo models covering highest development areas in the western region.
Process_Step:
Process_Description:
Aerial film was acquired and imaged in 2002 (Virginia Base Mapping Program (VBMP) color) and 2004 (Loudoun County annual aerial mission (black & white). The imagery was scanned at 21 microns. Ground control used to support the compilation and was collected by identifying strategic locations on the aerial photography plan and then determining the coordinates by GPS ground survey techniques.
The Aerial Triangulation was performed using softcopy workstations. Bundle adjustment was performed and Digital Elevation Models were created using and planimetric data were collected using standard photogrammetric collection techniques for breaklines and masspoints on soft copy workstations. Final deliverables in ESRI Interchange (E00) file format were placed on CD for delivery to OMAGI.
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Step:
Process_Description:
Each of the Base Map Data Layer coverages in the 27 delivery blocks comprising Phases I and II were loaded into a single Geodatabase Feature Class using ArcGIS Simple Data Loader. The entire feature class was then dissolved using ArcToolBox Dissolve, such that any adjacent features with identical values in all attributes consolidated into one feature. Record Counts, Frequencies, Length or Area summaries and final Topology checks were performed throughout the conversion procedure to ensure that multiple coverage data input matched single feature class data output (per TYPE code). 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%
Process_Date: 20050101
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: OMAGI
Contact_Position: Base Map Cartographer
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG File imported to Microstation V8, and overlaid with the Update Parcels DGN. Identified Areas to be corrected. 3. Remap area inside parcel change layer a. If no change is detected the entities are not modified b. If new features are found they are collected as per the specifications c. If there is difference in shape or size of the planimetric, environmental or topographic features these are modified and coded as Update_Date = '2005' 4. Review remainder of model area outside the parcel change area a. If new features found they are collected as per the specifications 5. Updated Plan data in the Parcel areas have been checked for Edge matching 6. DTM was modified in the 11 major update areas 7. Contours were generated and edge matched with the legacy contour data 8. Checked contour coding at all the new buildings. 9. Checked the updated data on Ortho for completeness 10. All clean up tools have been run 11. Exported to Coverages and then to GDB. 12. Split the Area wise GDB into manageable pieces 13. Run QA/QC on each part of the Area wise GDB 14. Errors marked in the Log file have been corrected in the merged database 15. Merged the different Areas data into a single GDB i.e., Pilot, Areas 1, 2, & 4 16. Dissolved the polygons with same feature codes 17. Clipped legacy data to Phase 3 delivery boundary 18. Loaded new Phase 3 data and merged with existing Legacy data in east. 19. Loaded complete data sets (11) to enterprise SDE geodatabase
Process_Date: 20050103
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: OMAGI
Contact_Position: Base Map Cartographer
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be remapped. 3. New features were collected as per the data dictionary and the features that do not exist on 2007 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2007'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Legacy PGDB was clipped to Phase 4 delivery boundary. 16. Updated Data was merged with the Legacy data. 17. Countywide complete dataset (11 layers) was loaded to enterprise SDE Geodatabase.
Process_Date: 20070604
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2008 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2008'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE Geodatabase.
Process_Date: 20090907
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: Base Map Cartographer
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2009 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2009'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2009 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE Geodatabase.
Process_Date: 20101020
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: Base Map Cartographer
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2012 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2012'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2012 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20130514
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Source_Information:
Source_Citation:
Citation_Information:
Title: Base Map Maintenance Services Contract, QQ-01407, 2013
Publication_Date: 20141218
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01407, 2013
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Process_Step:
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2013 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2013'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2013 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20140514
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150803
Title: Base Map Maintenance Services Contract, QQ-01857, 2014
Source_Scale_Denominator: 2400
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01857, 2014
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2014 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2014'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2014 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20150803
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20160825
Title: Base Map Maintenance Services Contract, QQ-01857, 2015
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01857, 2015
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2015 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2015'. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2015 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20160825
Source_Information:
Source_Citation:
Citation_Information:
Title: Base Map Maintenance Services Contract, QQ-01857, 2016
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01857, 2016
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2016 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2016. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2016 othos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20170804
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20181213
Title:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Source_Scale_Denominator: 2400
Type_of_Source_Media: none
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01857, 2017
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the central region of Loudoun County.
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2017 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2016. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2017 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20181213
Source_Information:
Source_Scale_Denominator: 2400
Type_of_Source_Media: none
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01857, 2018
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the northern region of Loudoun County.
Source_Citation:
Citation_Information:
Publication_Date: 20190904
Title: Contract # - QQ-01857, 2018
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2018 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2018. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2018 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20190904
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20210427
Title:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020
Source_Scale_Denominator: 2400
Type_of_Source_Media: none
Source_Citation_Abbreviation:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the Southeast region of Loudoun County.
Process_Step:
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Process_Description:
1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2020 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2020. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2020 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE
Process_Date: 20210427
Spatial_Data_Organization_Information:
Indirect_Spatial_Reference: Loudoun County
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: 4997
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: 0.00020833333333333297
Ordinate_Resolution: 0.00020833333333333297
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.WATER_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: WA_WELEV
Attribute_Definition: Elevation of water surface in feet
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: 0-2000 feet of elevation change in Loudoun County
Attribute:
Attribute_Label: WA_SOURCE
Attribute_Definition: Source that created or modified feature class
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: See Entity and Attribute Detail Citation for Data Dictionary
Attribute:
Attribute_Label: WA_UPD_DATE
Attribute_Definition:
The date a feature was last re-mapped, although it may have been reviewed for changes more recently
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: user generated text
Attribute:
Attribute_Label: WA_UPD_USER
Attribute_Definition:
Not for public distribution. Internal User ID of editor creating or modifying a feature. Intended to track and audit features internally by County.
Attribute_Definition_Source: Loudoun County
Attribute:
Attribute_Label: WA_TYPE
Attribute_Definition: Classification of Water Type
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: See Entity and Attribute Detail Citation for Data Dictionary
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 water body in SDE internal units
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: Positive whole numbers automatically generated
Attribute:
Attribute_Label: DB2GSE.SdeLength(SHAPE)
Attribute_Definition: Perimeter of water body in SDE internal units
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: Positive whole numbers automatically generated
Overview_Description:
Entity_and_Attribute_Overview:
WA_TYPE: Designation of water type code description ---- ------------------ 1 Double line stream 4 Lake or Pond 7 Dry Stormwater Retention Pond 10 Potomac River 11 Swamp/Marsh
Entity_and_Attribute_Detail_Citation:
Feature Depiction Descriptions based on USACE publication, EM 1110-1-1000, July 31, 2002 and further developed according to Loudoun County Data Dictionary.
Double line Stream [Type = 1] Digitize shorelines of streams, creeks or rivers wider than 15 ft, may or may not be navigable. Includes area hidden under bridges. ----------------------------------------------------------------- Lake or Pond [Type = 4] Shoreline of a large inland body of usually fresh water with a minimum area of 50' x 50' or .05 acre. Show man-made reservoirs as lakes. Ponds are bodies of standing water much smaller than a lake, often man-made. Water elevation attributed for all lakes and ponds greater than 1/10th of an acre. ----------------------------------------------------------------- Dry Retention Pond [Type = 7] Manmade stormwater retention pond typically associated with flood control structure and/or berm. Typically dry, but may contain marsh vegetation, takes precedence over marsh/swamp. Digitize at top of berm. This feature will not be attributed with a WA_WELEV value, but rather shall usually contain a spot elevation at the lowest point inside the smallest enclosed contour. ----------------------------------------------------------------- Potomac River [Type = 10] Digitize shorelines & islands of Potomac River bounding the County to the north. ----------------------------------------------------------------- Swamp or Marsh [Type = 11] Area of spongy, wet ground, usually harboring vegetation. No distinction is made between a swamp, marsh, or inundated area.
Overview_Description:
Entity_and_Attribute_Overview: WA_SOURCE: Source that created or modified feature class
Entity_and_Attribute_Detail_Citation:
code description ---- ------------------ 1 Legacy (pre 2002) 2 County 3 Contract
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 SE, 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: DXF
Format_Specification: AutoCAD Digital Exchange File
Digital_Transfer_Option:
Offline_Option:
Offline_Media: dvd
Fees:
Loudoun County distributes spatial data in ArcGIS database or shapefile or DXF format. Selected aerial imagery is also available.
Ordering_Instructions:
Visit our website at: <http://www.loudoun.gov/omagi> and click on "Maps and Data."  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: 20210427
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: Base Map Coordinator
Contact_Address:
Address_Type: mailing and physical
Address: MS 65
Address: 1 Harrison Street SE, 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, DXF, or .e00 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 2.9.12 on Fri Aug 06 14:08:49 2021