Spot elevations of Loudoun County, VA (2023)

Metadata also available as

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator:
Loudoun County, Virginia, Office of Mapping and Geographic Information (OMAGI)
Publication_Date: 20230724
Title: Spot elevations of Loudoun County, VA (2023)
Geospatial_Data_Presentation_Form: vector digital data
Description:
Abstract:
Spot Elevations are a base map data layer derived by automated processes and processed for cartographic representation at 1:2400 scale. The point features represent the heights of selected point locations as mapped from above. Spot Elevations are mapped to National Map Accuracy Standards (NMAS).NOTE: Spot Elevation points were updated using 2007, 2008 and 2009 imagery and are consistent with 5 foot topography. The 2012-2020 Basemap update Spot Elevation points will be consistent with 4 foot topography in that update area only. Future Basemap updates will ensure consistency throughout the rest of the County.
Purpose:
Spot elevations are gathered to record the terrain elevation at a particular point. Elevations are shown, when possible, for road forks, cul-de-sacs, and intersections, grade crossings, summits of hills, mountains and mountain passes, saddles, bottom elevations in depressions, and large flat areas. The County records spot heights in feet, and use this layer in conjunction with topography to ensure accurate elevation data.
Supplemental_Information:
Data are stored in the corporate ArcSDE Geodatabase as a point 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: -77.963008
East_Bounding_Coordinate: -77.314392
North_Bounding_Coordinate: 39.323858
South_Bounding_Coordinate: 38.837186
Keywords:
Theme:
Theme_Keyword_Thesaurus: none; Employee generated
Theme_Keyword: Height
Theme_Keyword: Elevation
Theme_Keyword: Spot
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: elevation
Place:
Place_Keyword_Thesaurus: none; Employee generated
Place_Keyword: County
Place_Keyword: Loudoun
Place_Keyword: Virginia
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:
Spot Elevations has 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 2024 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.)= 1.17; Tested 2.3 US Survey feet
Vertical_Positional_Accuracy_Explanation:
Tested points have been measured at 2.3 US Survey Feet vertical at 95% confidence level.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20020304
Title: Base Map Maintenance Services Contract, QQ-00986, Phase I
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: 20070312
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-01407, 2008
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-01407, 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: 20090309
Title: Base Map Maintenance Services Contract, QQ-01407, 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-01407, 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. Five foot contours were then generated from the compiled elevation data. Final deliverables in ESRI Interchange (E00) file format were placed on CD for delivery to OMAGI.
Process_Date: 20040105
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 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:
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: 20050117
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: 20070611
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: 20101011
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
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 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
Source_Information:
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.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150803
Title: Base Map Maintenance Services Contract, QQ-01857, 2014
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
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_Person_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: audiocassette
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 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: 20170804
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20181213
Title: Base Map Maintenance Services Contract, QQ-01857, 2017
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:
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
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20211206
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 South/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 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: 20211206
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20230724
Title:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2022
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2022
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_Person_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 2022 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= '2022. 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 2022 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: 20230724
Source_Information:
Source_Citation:
Citation_Information:
Title:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2023
Publication_Date: 20240824
Source_Scale_Denominator: 2400
Type_of_Source_Media: None
Source_Citation_Abbreviation:
RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2023
Source_Contribution:
Captured and updated photogrammetric stereo models covering selected areas in the Northern 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 2022 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= '2023. 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 2023 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: 20240824
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: Entity point
Point_and_Vector_Object_Count: 48008
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.SPOTELEV_POINT
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: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: SP_SELEV
Attribute_Definition: Elevation in feet
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: Elevation in feet
Attribute:
Attribute_Label: SP_SOURCE
Attribute_Definition: Source that created or edited feature class
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: See Overview Description for data dictionary of attrbute
Attribute:
Attribute_Label: SP_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: SP_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_Domain_Values:
Unrepresentable_Domain: User generated text
Overview_Description:
Entity_and_Attribute_Overview: SP_SOURCE: source by which feature was created or modified
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
Resource_Description: Offline Data
Distribution_Liability:
Chapter 54.1-402 of the Code of Virginia. "Any determination of topography or contours, or any depiction of physical improvements, property lines or boundaries is for general information only and shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination." Every reasonable effort has been made to assure the accuracy of these data. Loudoun County, Virginia does not assume any liability arising from the use of these data. These data are provided without warranty of any kind, expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular service. Reliance on these data is at the risk of the user. 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.
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: 20240824
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 Mon Dec 16 12:49:00 2024