This dataset is a single orthoimage from a collection of GeoTIFF format natural color orthoimages covering the islands of Puerto Rico, Mona, Desecheo, Culebra, Vieques, and the US Virgin Islands. 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 nominal 3.75 minute (in latitude and longitude) cell area. The source imagery was obtained in October 2004 and used to produce orthophotos with a one meter ground resolution. Imagery was acquired at 0.86 meter ground sample distance (GSD) resolution. Flight height maintained during mission was 27,000 feet AGL. The imagery was captured at 12-bit radiometric resolution and converted to 8-bit radiometric resolution during post processing. The imagery was obtained and processed by all digital means beginning with data acquisition using a Leica ADS40 Digital Airborne Sensor. The orthophotos are available in GeoTIFF form. The projected coordinate system is UTM zone 19 N, NAD 83, GRS 80, Units Meters.
The purpose of this project is to provide the United States Department of Agriculture's (USDA) Aerial Photography Field Office (APFO) with current true-color digital orthophotography for Puerto Rico, the U.S. Virgin Islands, and the surrounding islands. The APFO is the prime source of aerial imagery for USDA's research needs. The contracting agency for the project is the St. Louis District of the U.S. Army Corp of Engineers (USACE).
The data design specifications for this product includes several methods 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).
ground condition
The color 1-meter orthophotography acquired of Puerto Rico & Virgin Islands in 2003 & 2004 resides in the public domain and is stored at the U.S. Department of Agriculture's (USDA) Farm Service Agency (FSA) through interagency agreement number ISA-COE-0351.
1222 Spruce Street
Acknowledgment of the United States Army Corps of Engineers would be appreciated for products derived from these data.
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. Imagery was rectified to a recent LIDAR derived DEM. Aerotriangulation generates a RMSE for the positional accuracy of photo control for the final block adjustment to insure that the geo-reference accuracy of the imagery block is more than sufficient to support the specified orthorectification accuracy.
The data provided in this publication is a subset of coverage for the Rincon study area. Additional data is available for all of the islands of Puerto Rico, Culebra, Vieques, Mona, Desecheo, and the US Virgin Islands. Each orthophoto has an overedge of approximately 300 meters on all sides of its centering 3.75 minute cell.
These data are compiled to meet project specifications, which are that 90 percent of all well-defined points tested must fall within 10 meters.
Horizontal accuracy was checked using ground survey control collected contemporaneously with image acquisition. Ground survey consisted of photo identifiable points.
Image Acquisition for Orthophoto Production.
Ground control consisted of photo identifiable surveyed points. The imagery was collected at an altitude of 8229m using an ADS40 digital sensor. Image quality was verified during the post flight review phase. Factors considered during this review included but were not limited to the presence of smoke and/or cloud cover, contrails, light conditions and sun glint. The triangulated strips were rectified with a current LIDAR DEM of the area. The red, green, and blue bands were combined to produce the orthophoto. The ADS40 sensor collects twelve bit image data which requires radiometric adjustment for output in standard eight bit image channels. Converting to eight bit results in a reduction of the color range from 4096 to 256 - thus loss of radiometric detail is inevitable. The extra dynamic range of the sensor permits greater object differentiation in shadows and in bright areas. The sixteen bit dynamic range permitted the imagery to be more effectively color balanced than is possible with eight bit imagery. This was accomplished by performing tonal enhancements immediately prior to the reduction from sixteen bit to eight bit data. In addition to color balancing these eight bit images were adjusted to create seamless imagery to the highest extent practically achievable. The imagery was mosaicked using a combination of automated and manual seamlines generation. Project specified tiles were extracted from the mosaic. Final image tiles were reviewed for artifacts and anomalies and adjusted as part of quality control procedures. Adjacent images are compared for consistency in overlap regions.
3601 SW 2nd Ave., Suite Y
Internal feature number.
ESRI
Pixel value for red band of histogram
U.S. Geological Survey
Total count of value in image
U.S. Geological Survey
Internal feature number.
ESRI
Pixel value for green band of histogram
U.S. Geological Survey
Total count of value in image
U.S. Geological Survey
Internal feature number.
ESRI
Pixel value for blue band of histogram
U.S. Geological Survey
Total count of value in image
U.S. Geological Survey
384 Woods Hole Road
Although this data set has been used by the U.S. Geological Survey (USGS) and the U.S. Army Corps of Engineers (USACE), no warranty, expressed or implied, is made by the USGS or the USACE as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS or the USACE in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
GeoTIFF
GeoTIFF format image with world file and associated metadata
1222 Spruce Street