High-Resolution Orthorectified Imagery for Three Target Areas in Lake Clark National Park and Preserve (LACL), Southwest Alaska

ABSTRACT

This data series consists of orthorectified aerial photography for the coastal and nearshore areas of Lake Clark National Park and Preserve (LACL) of southwestern Alaska. The images cover three selected target areas: Glacier Spit, Silver Salmon, and Tuxedni Bay. The series consists of three timeslices: from 1993, 1978, and approximately 1950. The orthoimages were completed as part of a pilot study in collaboration between the University of Colorado (Institute of Arctic and Alpine Research) and the National Park Service (Southwest Network Inventory and Monitoring Program). Each high-resolution image has the qualities of a photograph and the functionality of a map layer for use in Geographic Information Systems (GIS) or remote sensing software. The eight orthorectified frames for 1993 are derived from 1:24,000-scale, black and white photographs acquired by Walker Alaska (now Aero-Metric) for the National Park Service (NPS). They have a pixel resolution of 0.3 m, an average relative horizontal accuracy of 7.2 m and cover a total of 200 km2. The three orthorectified frames for 1978 are derived from 1:65,000-scale, color-infrared (CIR) photographs acquired by the USGS and NASA, as part of the Alaska High Altitude Photography (AHAP) program. They have a pixel resolution of 1.0 m, an average relative horizontal accuracy of 17.3 m and cover a total of 675 km2. The five orthorectified frames for 1954 to 1957 are derived from 1:43,000-scale, black and white photographs acquired by the US Air Force. They have a pixel resolution of 0.6 m, an average relative horizontal accuracy of 15.5 m and cover a total of 500 km2. Digital scans of the photographs from ca. 1950, 1978 and 1993 were fully orthorectified in ERDAS Imagine using air-photo camera models, a Digital Terrain Model (DTM), information from calibration reports, and image-to-image control points linked to 2004-2006 IKONOS orthoimagery. This orthorectification procedure was refined after extensive testing of various software packages and settings. Horizontal errors could be reduced even further for small areas with minor adjustment.

Each of the 16 image files is in georeferenced .tif (GeoTIFF) format. Accessory shapefiles consist of attributed index map layers. All of the data layers share an Alaskan Albers projection and NAD83 datum, and are provided with FGDC-compliant metadata (in .html, .txt, and .xml formats). Also provided are a README file and a PowerPoint visual overview of the data series. Together, the three datasets make up a total of 91 files and 8.9 GB of data. The imagery is available through an unrestricted public license, and can be obtained on DVD by request (see Distributor contact information in the metadata).

The high-resolution imagery will be of interest to land managers, scientists, and others for observation and analysis of natural features and ecosystems. The orthoimagery complements recent IKONOS collections, and greatly improves both the resolution and accuracy of the previously georectified LACL coastal atlas. Beyond investigation of coastal erosion for these target areas, the three timeslices will be helpful to assess the status of environmental features, and to detect change in: 1) cultural resources and archeological sites; 2) ecosystem components such as geology, soils, lake and stream hydrology, and vegetation assemblages; and 3) marine, terrestrial, and freshwater habitats for a variety of animals. The imagery assists the goals of the NPS Southwest Alaska Network Inventory and Monitoring Program.

METADATA AND CITATION

PLEASE READ the FGDC-compliant metadata files that are available for each file (in .html, .txt, and .xml formats), which provide numerous details that may be of interest. Please cite this data release as: Manley, W.F., Lestak, L.R., and Parrish E.G., 2008, High-Resolution Orthorectified Imagery for Three Target Areas in Lake Clark National Park and Preserve (LACL), Southwest Alaska: Anchorage, AK: National Park Service, Southwest Alaska Network I&M Program. Digital Media.

CONTACT US

Southwest Alaska Network Data Manager
National Park Service
Southwest Alaska Inventory and Monitoring Program
240 West 5th Avenue
Anchorage, AK 99501
907-644-3684
dorothy_mortenson@nps.gov

William Manley, PhD
Institute of Arctic and Alpine Research (INSTAAR)
University of Colorado
1560 30th Street
Boulder, CO 80309-0450
303-735-1300
William.Manley@colorado.edu

RELEVANT LINKS

FILE LIST

DVD #1
File or Folder Name Target Area Title File Type Metadata Files Other Files Comments
0README_lacl_orthos.htm   Readme File (this file) HTML     List of files and folders
1LACL_Coastal_Imagery.ppt   Slideshow Overview of the Dataset PPT      
►Accessory_Layers     Folder      
lacl_ortho_1950a_index.shp   Index Map Layer of ca. 1950 Orthos Shapefile .html, .txt, .xml .dbf,.prj,.sbn,.sbx,.shx Includes detailed attributes
lacl_ortho_1978_index.shp   Index Map Layer of 1978 Orthos Shapefile .html, .txt, .xml .dbf,.prj,.sbn,.sbx,.shx Includes detailed attributes
lacl_ortho_1993_index.shp   Index Map Layer of 1993 Orthos Shapefile .html, .txt, .xml .dbf,.prj,.sbn,.sbx,.shx Includes detailed attributes
►lacl_ortho_1950_approx   1954-1957 Orthos Folder     5 Frames (2 GB)
lacl_ortho_1954_01_0122.tif Tuxedni Bay Ortho'ed Photo from ca. 1950, B&W, 1:43,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1957_05_0506.tif Silver Salmon Ortho'ed Photo from ca. 1950, B&W, 1:43,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1957_42_5594.tif Glacier Spit Ortho'ed Photo from ca. 1950, B&W, 1:43,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1957_43_5732.tif Tuxedni Bay Ortho'ed Photo from ca. 1950, B&W, 1:43,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1957_45_5966.tif Glacier Spit Ortho'ed Photo from ca. 1950, B&W, 1:43,000 GeoTIFF .html, .txt, .xml    
►lacl_ortho_1978   1978 Orthos Folder     3 Frames (2.3 GB)
lacl_ortho_1978_2667_7541.tif Tuxedni Bay Ortho'ed Photo from 1978, CIR, 1:65,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1978_2667_7547.tif Silver Salmon Ortho'ed Photo from 1978, CIR, 1:65,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1978_2667_7710.tif Glacier Spit Ortho'ed Photo from 1978, CIR, 1:65,000 GeoTIFF .html, .txt, .xml    
           
DVD #2          
File or Folder Name Target Area Title File Type Metadata Files Other Files Comments
0README_lacl_orthos.htm   Readme File (this file) HTML     List of files and folders
►lacl_ortho_1993   1993 Orthos Folder     8 Frames (4.6 GB)
lacl_ortho_1993_01_07.zip* Glacier Spit Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_01_09.tif Glacier Spit Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_05_05.tif Silver Salmon Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_05_07.tif Silver Salmon Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_05_09.tif Silver Salmon Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_05_11.tif Silver Salmon Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_09_03.tif Tuxedni Bay Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    
lacl_ortho_1993_09_05.tif Tuxedni Bay Ortho'ed Photo from 1993, BW, 1:24,000 GeoTIFF .html, .txt, .xml    

* This image has been compressed in .zip format.