2006-2007 false color infrared orthophotos covering the islands of Puerto Rico, Culebra, Vieques, St. Thomas, St. John, and St. Croix

This file is from a collection of GeoTIFF format natural color and false color infrared orthophotos covering the islands of Puerto Rico, Culebra, Vieques, St. Thomas, St. John, and St. Croix (USVI). An orthophoto is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthophotography combines the image characteristics of a photograph with the geometric qualities of a map. Each orthophoto provides imagery for a standard USGS 1/16th quadrangle map. False color infrared imagery was only generated for those 1/16th quadrangle maps falling within one kilometer of the coast line. The source imagery was obtained from November 2006 through March 2007 and used to produce orthophotos with a one foot ground sample distance (GSD). Imagery was acquired at 0.9 foot GSD resolution. Flight height maintained during mission was 8,650 feet AGL. The imagery was captured at 12-bit radiometric resolution and converted to 8-bit radiometric resolution during post processing. The imagery was captured with 30% sidelap between all adjacent flight lines. The PRVI project area was divided into 20 flight blocks due to necessary base station and flight line length requirements. The imagery was obtained and processed by all digital means beginning with data acquisition using an ADS40 digital sensor. The orthophotos are available in GeoTIFF form. The projected coordinate system is State Plane Puerto Rico / US Virgin Islands (Zone 5200), NAD 83, GRS 80, Units Meters.

Original contact information:

Contact Org: U.S. Army Corps of Engineers

Phone: 314-331-8385

Email: Robert.D.Mesko@mvs02.usace.army.mil

The purpose of the project is to provide the United States Army Corps of Engineers with current year digital orthophotos covering all of Puerto Rico and the US Virgin Islands. The Corps regularly uses digital orthophotos to support regulatory, land management and acquisition, planning, engineering and habitat restoration projects. The data may also become available to local, state and other federal agencies for their specific management and analysis needs. The one-foot resolution data collected for this project is higher resolution than the previous island-wide collection in 2004, which was one-meter resolution.

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The data design specifications for this product includes several directed to insure its quality, consistency, and usability. These specifications address some of the technical issues associated with orthoimage production: 1) the tops of buildings and other structures elevated above the surface of the ground 'tilt' away from the center point of the source photography and from their own bases as a result of perspective and their height which is not compensated for in digital elevation models of the ground surface and 2) individual orthoimages may be assembled from several source images (strips).

Users must assume responsibility to determine the usability of these data.

None

None. Acknowledgment of the United States Army Corps of Engineers would be appreciated for products derived from these data.

Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 2; ESRI ArcCatalog 8.3.0.800

The accuracy value was determined by measuring photo-identifiable control points collected with GPS survey methods in the orthophotos.; Quantitative Value: 5.00 meters, Test that produced the value: ASPRS Class I Standard for 200 Scale Mapping for areas defined in the document PR_USVI_DEM_Footprint07_Rev.pdf; Quantitative Value: 10.0 meters, Test that produced the value: ASPRS Class I Standard for 400 Scale Mapping for areas defined in the document PR_USVI_DEM_Footprint07_Rev.pdf

Cloud Cover: 5

These data cover all of the islands of Puerto Rico, Culebra, Vieques, and the US Virgin Islands. Each orthophoto has an overedge of approximately 30 meters on all sides of its centering 1.875 minute cell.

Sample points taken from overlapping areas of adjacent image strips that contributed image chips to each orthophoto tile are typically consistent to the 2-3 pixel level. This not only ensures that a consistent mosaic can be created from the adjacent image strips acquired with the ADS40 pushbroom scanner but also means that the images have good precision and as a group are spatially self-consistent.