| VGIN Color Digital Orthophotography, Spring 2009 | |
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Data format: SDE Raster Dataset File or table name: GISRSTR.GRSTR.COLOR_2009 Coordinate system: Lambert Conformal Conic Theme keywords: orthophotography, imagery, raster |
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Abstract:
In the spring of 2009, the Commonwealth of Virginia, through the Virginia Geographic Information Network Division (herein referred to as VGIN) of the Virginia Information Technologies Agency (VITA) contracted with the Sanborn Map Company to provide aerial data acquisition, ground control, aerial triangulation and development of statewide DTM and digital orthophotography data. The Virginia Base Mapping Program (VBMP) update project is divided into two collection phases: the Eastern half for Spring 2009 and the Western half for Spring 2011 with a 1,000' buffer to the state boundary. Ortho products are 1-foot resolution statewide ortho-imagery with upgrades to 6-inch resolution tiles and 3-inch resolution tiles in various regions within the project area. All data acquired in 2009 is jurisdiction based and is mostly in the eastern half of the state with upgrades requested in the western half of the state. The Virginia Base Mapping project encompasses the entire land area of the Commonwealth of Virginia over 4 years. The State boundary is buffered by 1000'. Coastal areas of the State bordering the Atlantic Ocean or the Chesapeake Bay are buffered by 1000' or the extent of man-made features extending from shore. |
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In the spring of 2009, the Commonwealth of Virginia, through the Virginia Geographic Information Network Division (herein referred to as VGIN) of the Virginia Information Technologies Agency (VITA) contracted with the Sanborn Map Company to provide aerial data acquisition, ground control, aerial triangulation and development of statewide DTM and digital orthophotography data. The Virginia Base Mapping Program (VBMP) update project is divided into two collection phases: the Eastern half for Spring 2009 and the Western half for Spring 2011 with a 1,000' buffer to the state boundary. Ortho products are 1-foot resolution statewide ortho-imagery with upgrades to 6-inch resolution tiles and 3-inch resolution tiles in various regions within the project area. All data acquired in 2009 is jurisdiction based and is mostly in the eastern half of the state with upgrades requested in the western half of the state. The Virginia Base Mapping project encompasses the entire land area of the Commonwealth of Virginia over 4 years. The State boundary is buffered by 1000'. Coastal areas of the State bordering the Atlantic Ocean or the Chesapeake Bay are buffered by 1000' or the extent of man-made features extending from shore.
The collection of aerial photography, update of the DTM surface and production of orthophotography was executed to capture the existing ground conditions at a specific point in time for the purpose of GIS analysis. Orthophotography along with DTM data typically provides an accurate base for digitally representing geographic features upon which a GIS is built. The Virginia Geographic Information Network Division (VGIN) is the lead public agency in the Commonwealth for spatial data and GIS. VGIN's mission is to facilitate the cost-effective development and use of spatial data, GIS, and related technologies in organizations throughout the Commonwealth.
The entire State was initially designed to support 1-foot resolution statewide ortho-imagery at 1"= 200' (1:2400) scale mapping. Jurisdictions throughout the State were provided an option to upgrade to 6-inch resolution tiles and 3-inch resolution at 1"=100' (1:1200) map scale. All digital ortho-imagery and development processes for the VBMP shall conform to the ASPRS Draft Aerial Photography Standards (1995) and Model Virginia Map Accuracy Standards (1992), which generally follow the ASPRS Accuracy Standard for Large-Scale Mapping (1990) for all imagery at the scales indicated except for the changes specified in this document. Accuracy will be tested and reported according to NSSDA Geospatial Positioning Accuracy Standards Part 3: National Standard for Spatial Data Accuracy Class 1.
ground condition
This VBMP 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" = 100' or 1" = 200' scale. It is requested that the Commonwealth of Virginia be cited for any use of the orthophotography as follows: "Imagery Courtesy of the Commonwealth of Virginia".
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No logical consistency tests were performed.
The project consisted of a total of approximately 20,000 total images in the Virginia North State Plane Zone for 1' = 200' and 1'=100' scale imagery.
The digital aerial imagery for the 1-foot resolution orthophotography was collected at an average flying height of 9350 feet above sea level with a DMC camera. The Ground control used to support the orthophotographic mapping was collected by either paneling of permanent monuments or photographic identification of strategic points. The coordinates were collected via ground survey techniques. Z/I ISAT software was utilized for the aerial triangulation phase, using high accuracy softcopy stereo plotters. A photogrammetric project was created, adding camera data, photo data, ground control point data and exterior orientation data. An interior orientation was performed for the project photos, automatic pass and tie measurements were executed and finalized with manual measurement of surveyed ground control. The final bundle adjustment was executed using Photo Triangulation (PhotoT) software. The 1-foot resolution or 1"=200' map data was segmented into 5,000' X 5,000' tiles and named according to they naming convention established and provide by VGIN. The DTM data was updated through photogrammetric stereo-compilation to North American Datum 1983; Virginia State Plane North or South Zone as applicable. All existing 2006 or 2007 DTM was updated and densified to a point spacing sufficient for producing orthos at the specified GSD and to generate accurate contours at the selected map scale. The DTM was updated using high accuracy stereo plotters and traditional manual photogrammetric techniques for collection of the breaklines and masspoints and delivered as Microstation v8 files. The bridges were coded uniquely and later delivered as a final ESRI geodatabase. Utilizing the raw images from DMC camera, DTM data, and digital aerial triangulation resulted in the creation of 4-band (RGB,CIR) digital orthoimagery. The geometric accuracy of the digital orthoimagery within each state plane coordinate zone will meet the Virginia Base Mapping standards for 1"=100' and 1"=200' scale mapping and reported according to the NSSDA standard at 95% confidence level Creation of 4-band (RGB,CIR) digital orthoimagery. The digital aerial imagery was rectified using the best algorithm, radiometrically balanced to produce digital imagery of nominally consistent tone and contrast and mosaiced to create a seamless orthophotography of the entire project area. The data was tiled and complete tiles were delivered as GeoTIFF with supplementary TFW files, as well as compressed JPG2000 files. The JPG200 files were compressed at a ratio of 5:1. Upon statewide acceptance of the DTM and Orthophotography the data is bundled and redelivered by jurisdiction.
11751 Meadowville Lane
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11751 Meadowville Lane