This dataset includes a series of quadrangle (quad) based image files that were created from a collection of GeoTIFF format natural color image tiles covering regions of Alabama, Louisiana, and Mississippi which were affected by Hurricane Katrina in late August 2005. The raw imagery used to generate the original image tiles was simultaneously collected with airborne Global Positioning System (GPS) and Inertial Measurement Unit (IMU) data, which was used to georeference the raw imagery. The raw imagery was rectified to a plane of constant elevation and mosaiced to generate the final image tiles. Each original image tile provided data for a nominal 1.875 minute (in latitude and longitude) cell area. The source imagery was obtained in September 2005 and was used to produce georeferenced, planar rectified imagery with a 1 ft. ground resolution. Imagery was acquired at 1 ft. Ground Sample Distance (GSD) resolution. Flight height maintained during mission was 10,000 ft. Above Ground Level (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 an ADS40 digital airborne sensor. The individual 1.875 minute image tiles were provided in GeoTIFF format in Geographic Coordinates (decimal degrees), NAD83. The 1.875 minute cell area GeoTIFFS were merged into 7.5 minute quad based mosaics and compressed on a Solaris system using LizardTech GeoExpress verion 5.0.6 software applying a compression ratio (cr) or 8:1 in a batch process without any enhancements or adjustments. It was determined that mosaics would be created for all quads in the project even when only a few of the sixteen 1.875 minute GeoTiffs required for complete quadrangle coverage of a particular quad were available. As a result, some of the quad mosaics in this dataset do not contain full 7.5 minute image coverage.
The general purpose of the imagery collection and processing is to provide data for federal and state agencies to visually denote and quantify damage areas from no damage areas, and to quantify the degree of damage as heavy, moderate or light.
The original images were clipped to the neatline of the USGS sixteenth quadrangle boundaries with the file naming pattern of 'K_MRC#_sixteenth#'. The K identifies the imagery as relating to Katrina, the MRC number is taken from the USGS quadrangle index, and the sixteenth number identifies which sixteenth quadrangle the image covers. The sixteenth numbers begin with '1' in the north west corner of the quadrangle and increase to '4', then they move back to the west and down one row to '5' and increase to '8', etc., until '16' is reached in the southeast corner of the quadrangle.
Date of Source Imagery Acquistion
None. Acknowledgment of the United States Army Corps of Engineers would be appreciated for products derived from these data.
Fort Worth Federal Center, 501 West Felix Street, Building 23, P.O. Box 6567
Sample points taken from overlapping areas of adjacent image strips that contributed image clips to each orthophoto tile are typically consistent to the 10-12 pixel level.
These data cover portions of Alabama, Louisiana, and Mississippi affected by Hurricane Katrina in August 2005. The quad mosaics were processed with available imagery, thus not all quad mosaics have complete coverage. Additional quads within this dataset area which have not yet mosaiced may become available at a later date.
These data are compiled to provide the most accurate product achievable within the scope of the project.
Relative horizontal accuracy was tested by measuring points in the overlap areas between image strips. Based on the expected accuracy of GPS / IMU solution used to georeference the imagery, this relative accuracy should be represenative of the absolute accuracy of the image strips.
Image Aquisition for Orthophoto Production.
Quadrangle Based Hurricane Katrina Damage Assessment Imagery
The imagery was collected at an altitude of 10,000 ft AGL using an ADS40 digital sensor. Image quality was verified during the post flight review phase to minimize cloud cover. Airborne GPS and IMU data were collected simultaneously with the imagery and merged during post processing to provide a combined position and orientation solution (POS). The POS data was used to georeference the raw image strips. The georefereneced image strips were planar-rectified to a constant elevation representative of the average elevation of a block. The red, green, and blue bands were combined to produce the resulting natural color orthos. The image strips were combined in a mosaic, and project specific tiles were clipped from the mosaic. No feathering was applied during mosaicing, causing seams between adjacent images to be visible in some tiles.
3601 SW 2nd Ave., Suite Y
MrSID compression of the GeoTiffs of the September 2005 Hurricane Katrina natural color images tiles covering impacted areas of Alabama, Louisiana, and Mississippi were batch processed. For the sake of expedience, no spectral enhancements or tonal adjustments were made in the processing of the data. LizardTech GeoExpress 5.6.0 software was processed on a Sun Solaris system. The compression ratio was 8:1.
Federal Center, 501 W. Felix St., Bldg. 23, P.O. Box 6567
The ADS40 Sensor provides three band imagery with pixel values between 0-255. The data are presented as natural color imagery with a number from 0-255 assigned to each pixel. This digital number refers to a color look-up table which will contain the RGB red, blue and green values.
Fort Worth Federal Center, 501 West Felix Street, Building 23, P.O. Box 6567
The data represents the results of data collection/processing for a specific U.S. Army Corps of Engineers activity and indicates the general existing conditions. As such, it is only valid for it's intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than it's intended purpose.
Federal Center, 501 W. Felix St., Bldg. 23, P.O. Box 6567