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Aerial Photography 2008
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2005 Sample 2008 Sample
MrSID files of just Wilmington & Blanchester are now available on a CD...
Contact the GIS Department to reserve a copy; e-mail us at merrittjoe@hotmail.com
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Remember, you must install the "Express View Browser Plug-in" from LizardTech to view these MrSID files.
The Grid can be viewed in a:
or
Click to launch Google Earth and view the 2008 Aerial Photography Grid. Below is a screenshot similar to what you will see first:
To view the 2008 images in MrSID file format, zoom into the area you want to see and click on the Information Point inside the grid (tile) that encompasses your area of interest.
NOTE: Only the images in Union Township are currently uploaded to the web as of 10-10-08, for the 2008 photography.
Then, click on the blue text as noted in the screenshot (above).
A folder will open up that contains several files, including one called (example) A605510_1.sid.
Screenshot of an example of an opened folder:
These MrSID files will be from the 2008 Aerial Photography flights, compressed to a 100:1 ratio from the original .tiff files.
If you want the original .tiff data, you can download a utility from www.Lizardtech .com that allows you to decompress the MrSID file back into the original .tiff file format from whence it came.
You can click on and view these MrSID files using a MrSID viewer, or you can download it and the accompanying world file (example: A605510_1.sdw) and view it with any GIS software.
What is a World File?
A world file is the companion file to a map or an image that includes basic plain-text information about location and scale, i.e. geo-referencing.
Download the ones you want and be sure to put them in the same folder on your computers hard drive that the associated MrSID files are in.
The world files and the .sid files must be in the same folder for them to work correctly together with GIS software.
Other data may be available in these folders, such as Metadata on each of the MrSID images or AutoCAD drawing files of 2-foot contours. They are all available to the public to download and are free to use.
Abstract for the 2008 Imagery Project:
The 2008 OSIP digital natural-color orthophotography county buy-ups were collected during the months of March and April (leaf-off conditions) with a resolution of 0.5-foot. Each county ortho buy-up was produced with a mapping scale of 1"=100', with an accuracy of +/- 2.5-feet. Imagery was collected with Leica ADS40 (sensor heads 51/52) digital cameras and rectified using LiDAR data. Imagery was acquired with an average overlap of 30 percent. The file naming convention is as follows: asxxxyyy or anxxxyyy= (e.g., 6-inch); Please note that xxxx and yyy represent the easting and northing coordinates (respectively) in state plane feet. Each geotiff ortho file is approximately 75MBs in size. Ownership of the data products resides with the State of Ohio and counties that elected to "buy-up". Orthophotography and ancillary data products produced through this contract are public domain data.
LiDAR was acquired Statewide to provide a solid and very accurate base to use during the image rectification process. This same LiDAR can be supplemented with 3D breaklines to generate 2-foot and/or 4/5-foot contours. The average post spacing between LiDAR points is 7-feet.
This orthophotography was delivered in tiles of 2500 feet by 2500 feet covering Clinton County in it's entirety.
Compliance with the accuracy standard was validated by the collection of photo identifiable GPS ground control points during the acquisition of aerial imagery. The following checks were performed.
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The ground control and airborne GPS data were validated through a fully analytical bundle aero triangulation adjustment.
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The LiDAR DEM data was checked against the project ground control. The technical staff confirmed the accuracy of the points during initial processing
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Digital orthophotography was validated through an inspection of edge matching and visual inspection for image quality.
The 1"=100' scale orthophotos were created to meet 2.5-foot horizontal accuracy, meeting NMAS.
The aerial imagery acquisition for the State of Ohio was flown to support the creation of digital orthophotography with a 0.5-foot pixel resolution. The 0.5-foot pixel ortho imagery was flown at an approximate altitude of 4,800-feet AMT. Imagery was flown with an average 30% overlap between flight lines. All imagery was collected using the Leica ADS40 (sensor heads 51/52) digital camera systems.
Woolpert Inc. acquired photo identifiable ground control points during and after the acquisition of aerial imagery. The ground control points were established using GPS for horizontal and vertical coordinate values. NAD83 (2005) - horizontal NAVD88 - vertical Geoid03 Grid US survey Feet State Plane Ohio South.