Loudoun County, Virginia, Office of Mapping and Geographic Information (OMAGI) unknown raster digital data Leesburg, Virginia Loudoun County, VA Loudoun County annually obtains leaf-off, aerial imagery in the spring. In 2012, the imagery was captured with a DMC 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 2002 VBMP 200-scale gridding schema (Virginia Geographic Information Network). 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. Data are stored in the corporate ArcSDE Geodatabase as a raster feature class. SDE geotabase imagery 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. unknown ground condition Complete None planned -77.983601 -77.308375 39.335910 38.836886 ISO19115 imageryBaseMapsEarthCover MEL Product Thesaurus Planimetric Wetlands Infrastructure or ground transportation Emergency management Environment Miscellaneous Land use or land cover Economic development Digital Orthophotography Tourism or recreation ISO 19115 Topic Categories structure transportation environment imageryBaseMapsEarthCover None County Commonwealth of Virginia Loudoun USA none. 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. Loudoun County, VA OMAGI Base Map Coordinator Base Map Coordinator mailing and physical

1 Harrison St. SE, 3rd Floor

PO Box 7000

Leesburg VA 20175 US 703.771.5778 703.771.5075 mapping@loudoun.gov 8:00-5:00 EST, M-F "March 2012 Photography flown by Sanborn Map Company, Colorado Springs, CO." "Digital Orthophotography compiled by Sanborn Map Company, Colorado Springs, CO" Not Available Not Available Microsoft Windows Server 2008 Version 6.0 (Build 6002) Service Pack 2; ESRI ArcGIS 10.0.3.3600 Where there is no data present, null data will be calculated as 0. All data was delivered "as-is" without removal image artifacts. There will be no overedge on the deliverable orthophoto tiles. 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: 12_DO_N17_7082_20.TIF. The first two characters represent the year of photography, ('102 = 2012). 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 2002 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. The project consisted of a total of 684 total images in the Virginia North State Plane Zone for 1' = 200' scale imagery. A random sampling method was utilized to locate 30 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 1.5 US Survey feet in the horizontal domain. Measured at a 95 percent confidence level, any point measured will be within 2.6 US Survey feet in the horizontal domain. 2.6 US Survey feet or Circular RMSE 1.5 feet Compiled to meet 2.6 feet horizontal accuracy at 95 % confidence level in accordance with National Standards for Spatial Data Accuracy (NSSDA). Not Available Loudoun County, VA OMAGI 12000 hardDisk ground condition VA-081223-SANB digital imagery produced by the DMC camera 3. Sanborn performed DAT on the digital stereo images using the ground control points from 2009 Virginia Base Map Program (VBMP) within Loudoun County. 4. Using the DAT solution and updated DTM, orthophotos were generated at 1ft resolution. Additional DEM was collected at the edge of county to complete coverage. 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 10 (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 22:1 9. A full mosaic of all the ortho photos is created in MrSID MG3 format with 22:1 compression ratio. Sanborn Map Company mailing and physical

1935 Jamboree Drive, Suite 100

Colorado Springs CO 80920 US 866.726.2676 719.528.5093 coloradosprings@sanborn.com www.sanborn.com 1. Sanborn acquired aerial imagery using the DMC mapping camera on March 8th and 20th, 2012. The digital aerial imagery for the 1-foot resolution orthophotography was collected at an average flying height of 9350 feet above sea level. 2. Sanborn processed digital images to jp2 format using Intergraph image processing software, for use in AT and digital ortho production. Sanborn Map Company mailing and physical

1935 Jamboree Drive, Suite 100

Colorado Springs CO 80920 US 866.726.2676 719.528.5093 coloradosprings@sanborn.com www.sanborn.com Pixel 180000 190000 1 NAD 1983 StatePlane Virginia North FIPS 4501 Feet 38.03333333333333 39.2 -78.5 37.66666666666666 11482916.66666666 6561666.666666666 coordinate pair 0.00000002708842039567117 0.00000002708842039567117 Foot_US D North American 1983 GRS 1980 6378137.0 298.257222101 Loudoun County Office of Mapping & Geographic Information (OMAGI) Public Information Counter mailing and physical

PO Box 7000

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

Leesburg VA 20175 US 703-771-5778 703-771-5075 mapping@loudoun.gov 8:00-5:00 EST, M-F 2012 Digital Orthophoto 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. GeoTIFF 6.0 6.0 no compression applied Contact OMAGI Public Information Counter Select ortho tile images and complete order form: Visit our website at: http://www.loudoun.gov/omagi, click on "OMAGI Documents and Information." Our "Products & Services" link will lead you to order forms and 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. 20120824 County Office of Mapping and Geographic Information Base Map Coordinator mailing and physical

PO Box 7000

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

Leesburg VA 20175 US 703-771-5778 703-771-5075 mapping@loudoun.gov Monday - Friday 8:00 - 5:00 EST FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time 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. Not Available Unclassified Not Available