1' Color Digital Orthophotography of Loudoun County, VA (Spring 2024)

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Loudoun County, Virginia, Office of Mapping and Geographic Information (OMAGI)

Publication_Date: 06252024

Publication_Time: Unknown

Geospatial_Data_Presentation_Form: remote-sensing image

Publication_Information:

Publication_Place: Leesburg, Virginia

Publisher: Loudoun County, VA

Title:

1' Color Digital Orthophotography of Loudoun County, VA (Spring 2024)

Description:

Abstract:

Loudoun County annually obtains leaf-off, aerial imagery in the spring. Since 2004, the County has utilized this imagery to support the development of an annual digital orthophoto base. In 2024, the imagery was captured with a Vexcel Ultracam Eagle digital camera, in 4-band (R,G,B, and NIR) format. These files contain 1-foot ground-resolution, 8-bit, 4-band orthorectified aerial image map products in GeoTIFF version 6.0 file format. GeoTIFF files are uncompressed raster images complete with TFW coordinate information. The aerial imagery project encompasses the entire land area of the County of Loudoun, VA. Images were flown during leaf-off conditions and cover 5000' by 5000' and are tiled according to the VBMP 200-scale gridding schema (Virginia Geographic Information Network).

Purpose:

This annual digital ortho effort is implemented and administered by the Loudoun County Office of Mapping and Geographic Information. While primarily developed to capture annual base planimetric, environmental, and topographic updates throughout the County, the backdrop image can also serve as a reference layer for GIS analysis, Computer-aided Dispatching and E-911 services, Staff planning and development, historical record in land use/land cover change, and has the potential for use in many other public service projects.

Supplemental_Information:

Data are stored in the Image ServeR and is available in the County's GIS, whereas copies of source files are provided for public distribution.
The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN.
Digital Terrain Models were collected for the purposes of orthorectification.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 02032024

Time_of_Day: unknown

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: Annual

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -77.523659

East_Bounding_Coordinate: -77.505852

North_Bounding_Coordinate: 39.113372

South_Bounding_Coordinate: 39.099498

Keywords:

Theme:

Theme_Keyword_Thesaurus: MEL Product Thesaurus

Theme_Keyword: Digital Orthophotography

Theme_Keyword: Land use or land cover

Theme_Keyword: Emergency management

Theme_Keyword: Miscellaneous

Theme_Keyword: Planimetric

Theme_Keyword: Economic development

Theme_Keyword: Environment

Theme_Keyword: Wetlands

Theme_Keyword: Infrastructure or ground transportation

Theme_Keyword: Tourism or recreation

Theme:

Theme_Keyword_Thesaurus: ISO19115

Theme_Keyword: imageryBaseMapsEarthCover

Place:

Place_Keyword_Thesaurus: none

Place_Keyword: Commonwealth of Virginia

Place_Keyword: Loudoun

Place_Keyword: County

Place_Keyword: USA

Access_Constraints: none.

Use_Constraints:

Data was generated for use by Loudoun County and are available to the public. This image data has been developed using procedures designed to produce data to National Standard for Spatial Data Accuracy (NSSDA) and is intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.
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.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA OMAGI

Contact_Person: Base Map Coordinator

Contact_Position: Base Map Coordinator

Contact_Address:

Address_Type: mailing and physical address

Address: 1 Harrison St. SE, 3rd Floor

Address: PO Box 7000

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: 8:00-5:00 EST, M-F

Data_Set_Credit:

"February 2024 Photography flown by the Sanborn Map Company, Colorado Springs, CO." "Digital Orthophotography compiled by Sanborn Map Company, Colorado Springs, CO"

Security_Information:

Security_Classification_System: Not Available

Security_Classification: Public Information

Security_Handling_Description: Not Available

Native_Data_Set_Environment: ESRI ArcMap 10.6.1

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Where there is no data present, null data will be calculated as 255. All data was delivered "as-is" without removal image artifacts. There will be no overedge on the deliverable orthophoto tiles.

Logical_Consistency_Report:

The dataset contains raster images of digital orthophotography so the logical consistency report is not applicable. The file naming convention is based on the lower left/southwest corner of the image. Tile names are 17 characters long with a 3 character extension. An example tile name is: 24_DO_N17_7082_20.TIF. The first two characters represent the year of photography, ('24 = 2024). The next two characters represent the product code (DO = digital orthophotograph, TM = terrain model). After an underscore to separate the code, the following three characters are the Prefix to maintain uniqueness in the project. The first character indicates the state plane zone (N = North, S = South), and the next two numbers indicate the coordinate pairing of the million units of the Easting and Northing coordinates for the lower left/southwest corner of the tile. The remaining numbers are duplicated from the same grid system emplyed in the VBMP program at Virginia Geographic Information Network. An underscore separates the Prefix from the BMU (Base Modular Unit) of the next four numbers. The Base Modular Unit designates the name for 1:4800 scale imagery tiles which correspond to a 10,000 foot grid based on even 10,000 increments of the Virginia State Plane. Following another separator is a two number suffix. The first digit of the Suffix number designates the quadrant of the BMU that a nested 5,000 foot tile grid occupies. Quadrants are numbered from 1 to 4 starting with the Lower Left quadrant of the BMU, increasing in a clockwise direction. The second digit of the Suffix number designates the quadrant of the 5,000 foot tile that a nested 2,500-foot tile grid occupies. Quadrants are numbered from 1 to 4 starting with the Lower Left quadrant and increasing in a clockwise direction.

Completeness_Report:

The project consisted of a total of 684 total images in the Virginia North State Plane Zone for 1' = 200' scale imagery.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

A sampling method was utilized to locate 22 independent checkpoints points over the entire project area to be used in the accuracy assessment. Previously measured or surveyed points were used as a reference points. The resultant accuracy of the measurements yield a circular RMSE of .61 US Survey feet in the horizontal domain. Measured at a 95 percent confidence level, any point measured will be within 1.21 US Survey feet in the horizontal domain.

Quantitative_Horizontal_Positional_Accuracy_Assessment:

Horizontal_Positional_Accuracy_Value: Circular RMSE 0.61 feet

Horizontal_Positional_Accuracy_Explanation:

Compiled to meet <4.92 feet horizontal accuracy at 95 % confidence level in accordance with National Standards for Spatial Data Accuracy (NSSDA).

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report: Not Available

Quantitative_Vertical_Positional_Accuracy_Assessment:

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: Loudoun County, VA OMAGI

Publication_Date: 06252024

Title:

1' Color Digital Orthophotography of Loudoun County, VA (Spring 2024)

Source_Scale_Denominator: 12000

Type_of_Source_Media: Hard Disk

Source_Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 03062024

Source_Currentness_Reference: ground condition

Source_Contribution: digital imagery produced by the Vexcel UtraCam camera

Process_Step:

Process_Description:

1. Sanborn acquired aerial imagery using the Vexcel Ultracam mapping camera on February 3rd, 2024. The digital aerial imagery for the 1-foot resolution orthophotography was collected at an average flying height of ~19,600 feet above sea level. 2. Sanborn processed digital images to tif format using UltraMap image processing software, for use in AT and digital ortho production.

Process_Date: Spring 2024

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Sanborn Map Company

Contact_Voice_Telephone: 866.726.2676

Contact_Facsimile_Telephone: 719.528.5093

Contact_Electronic_Mail_Address: coloradosprings@sanborn.com

Contact_Instructions: www.sanborn.com

Contact_Address:

Address: 1935 Jamboree Drive, Suite 100

City: Colorado Springs

State_or_Province: CO

Postal_Code: 80920

Country: USA

Address_Type: mailing and physical address

Process_Step:

Process_Description:

3. Sanborn performed DAT on the digital stereo images using the ground control points from 2014 Virginia Base Map Program (VBMP) within Loudoun County as well as control points collected by Sanborn as part of the USGS Northern VA Lidar program in winter of 2022. 4. Using the DAT solution and updated DTM, orthophotos were generated at 1ft resolution. 5. The orthos were color balanced and then mosaiced using seamlines. 6. The mosaics were checked and corrected for any color differences, bridge distortions, etc. 7. The mosaics are cropped according to the VBMP tile grid with standard VBMP naming convention with the prefix 22 (to identify the year of imagery) 8. The tiles were submitted in TIFF format with ESRI compatible world files as well as compressed MrSID files. MrSID files were compressed at a ratio of 20:1 9. A full mosaic of all the ortho photos is created in MrSID MG3 format with 22:1 compression ratio.

Process_Date: Spring/Summer 2024

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Sanborn Map Company

Contact_Address:

Address_Type: mailing and physical address

Address: 1935 Jamboree Drive, Suite 100

City: Colorado Springs

State_or_Province: CO

Postal_Code: 80920

Country: USA

Contact_Voice_Telephone: 866.726.2676

Contact_Facsimile_Telephone: 719.528.5093

Contact_Instructions: www.sanborn.com

Contact_Electronic_Mail_Address: coloradosprings@sanborn.com

Cloud_Cover: 0

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Pixel

Row_Count: 5000

Column_Count: 5000

Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column

Coordinate_Representation:

Abscissa_Resolution: 1.000000

Ordinate_Resolution: 1.000000

Planar_Distance_Units: survey feet

Map_Projection:

Map_Projection_Name: Lambert Conformal Conic

Lambert_Conformal_Conic:

Standard_Parallel: 38.033333

Standard_Parallel: 39.200000

Longitude_of_Central_Meridian: -78.500000

Latitude_of_Projection_Origin: 37.666667

False_Easting: 11482916.666667

False_Northing: 6561666.666667

Geodetic_Model:

Horizontal_Datum_Name: D_North_American_1983_HARN

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_Resolution: 1.000000

Altitude_Encoding_Method: Explicit elevation coordinates do not apply to this layer

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Band 1

Entity_Type_Definition: Red Band 8-bit

Entity_Type_Definition_Source: Processed from Vexcel Ultracam camera

Detailed_Description:

Entity_Type:

Entity_Type_Label: Band 2

Entity_Type_Definition: Green Band 8-bit

Entity_Type_Definition_Source: Processed from Vexcel Ultracam camera

Detailed_Description:

Entity_Type:

Entity_Type_Label: Band 3

Entity_Type_Definition_Source: Processed from Vexcel Ultracam camera

Entity_Type_Definition: Blue Band 8-bit

Detailed_Description:

Entity_Type:

Entity_Type_Label: Band 4

Entity_Type_Definition: NIR Band 8-bit

Entity_Type_Definition_Source: Processed from Vexcel Ultracam camera

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Loudoun County Office of Mapping & Geographic Information (OMAGI)

Contact_Position: Public Information Counter

Contact_Address:

Address_Type: mailing and physical address

Address: 1 Harrison Street, S.E., 2nd Floor

Address: PO Box 7000

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: 8:00-5:00 EST, M-F

Resource_Description: 2024 Digital Orthophoto

Distribution_Liability:

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.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: GeoTIFF 6.0

Format_Version_Number: 6.0

File_Decompression_Technique: no compression applied

Digital_Transfer_Option:

Fees: Contact OMAGI Public Information Counter

Ordering_Instructions:

Select ortho tile images and complete order form: Visit our website at: <http://www.loudoun.gov/omagi>, click on "Maps and Data, link will lead you to order lists of available 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: 06252024

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: County Office of Mapping and Geographic Information

Contact_Position: Base Map Coordinator

Contact_Address:

Address_Type: mailing and physical address

Address: 1 Harrison Street, S.E., 2nd Floor

Address: PO Box 7000

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: Monday - Friday 8:00 - 5:00 EST

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Access_Constraints: none

Metadata_Use_Constraints:

This metadata was created in xml file format and specific elements may not apply if your data is exported to other formats. 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.

Metadata_Security_Information:

Metadata_Security_Classification_System: Not Available

Metadata_Security_Classification: Unclassified

Metadata_Security_Handling_Description: Not Available