Using DOQQs with desktop GIS software

DOQQ data which comes on CD-ROM can be used with many software packages. Check your software's documentation for instructions on using JPEG images. Instructions for DOQQ use with selected desktop mapping packages are available through this page. The availability on this page of instructions for specific software packages is not an endorsement of these software packages; these are packages that NCGS staff have experience with.

• Arcview 3.X
• Mapinfo 4.X - 5.X
• ArcExplorer 1.1

Arcview 3.X

Arcview 3.0a and 3.1 can be used to view DOQQ CDs available from the NCGS. How the image is used depends on the format of the CD. Twenty seven county CDs are in "Original" format. The rest of the county CDs are in "Revised" format. A description of differences in CD formats is here. There are two options when working with Arcview 3.X and DOQQs.

Use either one of the following extension to view images directly from the CD.:

• 2) DOQQ Display Utility for NCDENR: version 1.2 (selected DOQQs can be copied to another location and added to the View.) May 27, 1999
• 1) DOQQ Display Utilities: a utility developed by the Minnesota Dept. of Natural Resources. This will only work with "Original" format CDs.

The extension developed for NCDENR is compatible with header files of either format. You don't have to know what kind of CD you have, Arcview figures it out all by itself. If you move DOQQs from CDs to the hard drive, you can store DOQQs with either kind of header file in the same directory and view them together without worrying about which are "Original" or which are "Revised".

To use the extension, download the zip file and extract the *.avx file to the ext32 directory. Consult your documentation for where Arcview is installed and the location of the "ext32" subdirectory.

Once installed a new button is added to the Button Bar when a View is active. Clicking this button prompts for the location of the DOQQs.

If the CD is "Revised" format, and you do not need to view the DOQQs directly from the CD, follow these instructions:

• Copy the image you want to view onto your hard drive. Images have one of the following four extensions to the filename: ".nec", ".nwc", ".sec", ".swc".
• Copy the corresponding "world file" into the same directory with the image. World files are contained in a "tar" archive in the "world" subdirectory in the "data" directory where the images are stored. "Winzip" software is a common compression program which will open the tar archive. Extract the world file, which will have one of the following four extensions to the file name: ".necw", ".nwcw", ".secw", ".swcw". The first 8 characters of the image file name and the world file name should be the same.
• Rename the image so that the file extension is now ".jpg". Rename the world file so that the first part of the filename is the same as the image and the extension is ".jgw". Be careful: Images for quarterquadrangles from the same quadrangle will have the same name and a different extension. You will need to make sure all DOQQs have unique filenames. Now you can add this image as an Image Theme in Arcview. See the Arcview documentation for adding Image themes.

Coming soon.

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