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DIGITAL ORTHOPHOTO QUADRANGLES (DOQs) |
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Use of DOQs for GIS Applications A DOQ image can be displayed in either ArcInfo or ArcView GIS application software by changing the file name extension from .doq to .bil. The .bil stands for "band interleaved by line". You will also need a header file (text format) with the same file name but having the .hdr extension. This file is different from the previous header files discussed above. The .hdr file tells the number of rows, columns, bytes of header to skip, and the x-y location of the upper left hand corner pixel. Links are provided to view this file with each DOQ under the option above of Select a DOQ. If you are downloading a COQ the following software will be helpful in uncompressing a COQ to create a DOQ and creating the .hdr file. After you have uncompressed the COQ and created a DOQ and the appropriate .hdr file, then you can change the file name extension of the DOQ from .doq to .bil in order to display it in ArcInfo/ArcView. Some applications in ArcInfo may require you to import the image as a grid. Some graphics software like Paint Shop Pro, can display COQs directly without uncompressing it, if the .coq extensions are changed to .jpg extensions. Other software like MS Photo Editor that support JPEG images can not display a COQ because it is too large for the software application. Freeware for displaying DOQs A copy of the freeware software called "ArcExplorer" is available from the Environmental Systems Research Institute (ESRI), Redlands, California. The ArcExplorer can view and zoom a DOQ coverage. A complete description of the ArcExplorer software can be found at the ESRI website located below . ArcExplorer can be downloaded from the ESRI website or from the DNR website.
If you are currently using any version of ESRIs MapObjects in a development environment, you will need to either reinstall the MapObjects onto your system, or re-register all components in the installation directory. User RequestComments and Suggestions
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