Orthorectification of historic imagery for Lake Clark National Park and Preserve and Katmai National Park and Preserve: Final report

Robertson, Andrew; Knopf, Jeffrey; Johnson, David; Maffitt, Bonnie

Historical imagery is an important asset for the management of the nation’s natural resources and serves as a point-in-time record for the assessment of conditions such as: vegetative cover; surface hydrology; wildfire fuel regimes; erosion and deposition; and glacial extent. Alaska’s historical imagery frequently consists of scanned hard-copy black and white and color-infrared (CIR) aerial photography acquired through the Alaska High Altitude Aerial Photography Program (AHAP). In this assessment individual black and white, CIR AHAP, and coastal CIR aerial photographs for Lake Clark National Park and Preserve (LACL) and Katmai National Park and Preserve (KATM) are cataloged as both individual orthorectified images and as single seamless mosaic base maps for the time periods of: 1950s and 1980s. Orthorectified coastal aerial images from 2010 and 2011 are also available, however, only as individual images. The primary objective of this project was to create a digital library of historic aerial photographs that were georeferenced, orthorectified and available for comparison with current imagery from LACL and KATM. Secondarily, this project provided students with the opportunity to learn how to convert data, georeference, orthorectify, mosaic, and color balance, among other skills. Three different software packages were utilized in the creation of the final products thus giving student technicians the opportunity to get hands on experience with different software and increase their understanding of the development of project methodologies. With the advent of new remote sensing and geographic information systems (GIS) technologies, hard-copy individual aerial imagery can now be converted to digital form through a series of procedures including: pre-processing; georeferencing; orthorectification; and, validation through quality assurance and quality control assessments. The resulting digital products can be cataloged as both individual images and seamless mosaics. Throughout the performance period of this project, the Southwest Alaska Network (SWAN) of the National Park Service Alaska Region and Saint Mary’s University of Minnesota cooperatively compiled a library of 2,142 individual orthorectified images and produced seamless mosaics for both parks. In addition, this project provided the opportunity to test new datasets and processes including: WARP NGA base imagery within LACL; and, the orthorectification of IKONOS images with higher resolution SPOT 5 digital elevation models (DEM) within KATM. As a follow-on to the aerial photo orthorectification, SMUMN created image mosaics that digitally merged individual orthorectified images together into larger composite images for both the black and white and AHAP orthorectified images. These large format orthorectified image products now permit digital comparison with newly acquired imagery bases such as IKONOS and SPOT 5, where available, and can facilitate informed resource management decisions throughout LACL and KATM. This report documents a two-phase project in which historical air photos were orthorectified to the IKONOS base imagery for LACL and KATM (Phase 1), and park wide orthorectified photo mosaics were produced for the years of 1950’s black and white photos and also for the 1980’s AHAP photography (Phase 2).

Orthorectification of historic imagery for Lake Clark National Park and Preserve and Katmai National Park and Preserve: Final report

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