Resource Description: The data are being provided on an 'as is' basis. The Corps specifically disclaims any warranty, expressed or implied, including, but not limited to, the implied warranties or merchantability and fitness for a particular use. The entire risk as to quality and performance is with the user. In no event will the Corps or its staff be liable for any direct, indirect, incidental, special, consequential, or other damages, including loss of profit, arising out of the use of these data even if the Corps has been advised of the possibility of such damages. All data are intended for resource management use.
The triangulated strips were rectified with a recent DEM of the area provided by 3001, Inc. The vertical accuracy of the DEM varies based on the elevation postings and is generally estimated at 30-45cm. The red, green and blue bands were combined to generate a final natural color orthophoto, and the near - infrared, red and green bands were combined to generate a final false color infrared 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 banancing 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 pecified tiles were extracted from the mosaic. Final image tiles were reviewed for artifacts and anomalies and adjusted as part of quality control procedures. When necessary, local corrections to the imagery were performed to minimize such effects.