This dataset was created through orthorectification of SPOT imagery using USGS Digital Orthophoto Quadrangles and Maine DEMs in ERDAS OrthoBASE 8.7. The orthorectified imagery was then warped using Space Imaging's proprietary Autowarp software. Autowarp computes tie points between two images based on correlation between similar points in the images and then applies a locally varying warp based on the tiepoints. The program was given an initial set of ground control points to create a coarse quadratic warp which was then refined through the addition of more points selected by the program. This work was done by Space Imaging and Sanborn staff.
Certain high-elevation areas were further orthorectified by i-cubed to reduce horizontal error.
Color balancing for the mosaic was done using GIMP image processing software by Maine DEP GIS staff. Note that balancing was done to enhance vegetated areas. In most cases, this means loss of contrast in urban areas. The raw data are much darker, but would provide more detail in urban areas than these processed data (at the expense of loss of contrast in vegetated areas).
These data are part of the MELCD 2004 landcover and impervious mapping project for Maine.
The data are LICENSED to the following entities:
-Federal Government organizations when working with Maine on joint projects -All State Government departments and agencies within Maine -Regional county and local governments within Maine -K-12 schools, State Colleges and Universities within Maine
These data are NOT freely transferable or reproducible, and can only be utilized by the above licensees. Private companies, nonprofits, and private schools are not licensees. Licensees may share the data with non-licensees only when working in concert on a project initiated by a licensee, and only on the condition that non-licensees remove the data at the termination of the project, and only use the data for that project.