2020 NOAA NGS 4-band Ortho-rectified Color Mosaic of Ketchikan, AK

This data set, acquired by Quantum Spatial, Inc., contains ortho-rectified mosaic tiles, created as a product from the NOAA Integrated Ocean and Coastal Mapping (IOCM) initiative. The source imagery was acquired on 20200911 with an UltraCam Eagle Mk3 sensor.

Ortho-rectified mosaic tiles are an ancillary product of NOAA's Coastal Mapping Program (CMP), created through a wider Integrated Ocean and Coastal Mapping initiative to increase support for multiple uses of the data.

The ground sample distance (GSD) for each pixel is 0.25 meters. The imagery was not tide coordinated at the time of acquisition.

Users must assume responsibility to determine the usability of these data. These photographs were obtained for use by NGS during the course of its development of potential final products to fulfill its statutory mission. Although NGS is making these photographs available to others who may find the photographs of value, NGS does not warrant, endorse, or recommend the use of these photographs for any given purpose. NGS is providing these photographs "as is," and NGS disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will NGS be liable to you or any third party for any direct, indirect, incidental, consequential, special, or exemplary damages or lost profits resulting from any use or misuse of these data. Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners

Data is available online for custom downloads

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

OS Independent

The project specifications require that only horizontal accuracy be computed for orthoimagery files. The required accuracy meets or exceeds ASPRS standards. The horizontal accuracy was tested with 8 checkpoints located throughout the project area. These checkpoints were not used in the calibration or post-processing of the imagery data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. The x and y positions of where the checkpoints fell on the orthoimagery were collected. These values were then compared to the surveyed control point x and y values.

Qualitative value: Tested 0.047 meters RMSEx. The RMSEx of the imagery was calculated using 8 checkpoints. Tested 0.028 meters RMSEy. The RMSEy of the imagery was calculated using 8 checkpoints. Tested 0.055 meters RMSEr. The RMSEr of the imagery was calculated using 8 checkpoints.

The extent of image coverage is limited to the acquired flight lines which were planned to map the shoreline and therefore may not include all areas within the bounding coordinates.

All rectified images were loaded in Global Mapper to view the entire project area for tone differences, complete coverage, warping/smearing imagery due to inaccurate DEM, and any other obvious problems. All final tiles are reviewed for artifacts, unblended seam-lines and warps or smears and then corrected using Photoshop.