South Carolina DOQQ Archive

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    Q. How do I view the DOQQ without connecting to the Internet ? The doq files can also be downloaded and viewed with free plugins from LizardTech Inc. Some of the plugins include: desktop, ArcView, Adobe products, and several high-end commercial mapping programs. Visit LizardTech Inc. Publishing page to download the latest.  Get the plugin for Windows 95/98/NT. Get the help file for loading the Windows 95/98/NTdesktop plugin.

    Q. How do I view the metadata database ? The metadata database is a Microsoft Access database. If you own Access, download the file and double click on the file name to open and view. (Metadata Database File)

    Q. How do I download the data ? With Netscape browser, place the cursor over the DOQQ file name in the left of the view window, hold the shift key down and left click. Follow this procedure for both the .SID file and the .SDW file. The .SDW file is optional, and used only with mapping systems.
    With the Internet Explorer browser, place the cursor over the DOQQ file name in the left of the view window and click the right mouse button. Select "Save Target As..." from the menu options. Follow this procedure for both the .SID file and the .SDW file. The .SDW is optional, and used with mapping systems.

    Q. How do I export a SID file to a open format ? LizardTech provides a free viewer that can be downloaded from their web site. While displaying the image in the  Viewer, click the small TIF icon located in the upper left menu bar. This will provide numerous export options for file sizes.

    Q. Why do these images have a red hue to them ? The original film used to capture the photography was a color infrared type. Color infrared film is frequently used because it can detect a wider range of the electromagnetic spectrum then the human eye. The varying hues of red can be used to detect stress in vegetation by moisture content.

    Q. Why is there a variation in color among the images ? The photo mission was probably collected over many days, at different times of day, with multiple rolls of film and possibly developed with different batches of chemicals.

    Q. How can I use a DOQQ in ArcView 3.1 or 3.2 ? ArcView 3.2 can read .SID & .SDW files directly. Remember to load the MrSID Image Support extension with ArcView 3.1.

    Q. How do I mosaic a bunch of these DOQQs together ? For graphic purposes, Adobe Photoshop is an excellent tool. Lizardtech offers a free Adobe Photoshop plugin for reading files. For mapping purposes, use an image processing package like ERDAS Imagine, PCI or ENVI for best results. In ArcView you can mimic a mosaic, by building an image catalog. ArcView provides a good hepl section on how to do this.

    Q. How do I get a DOQQ into another projection ? This requires special tools usually found in mid to high-end mapping/image processing packages. It cannot be done by just changing the .SDW file coordinates.

    Q. How do I print a DOQQ ? This is dependant on the application software that you are using to view the data. Most programs will require that the image be uncompressed prior to printing, and will attempt to de-compress "on-the-fly". Because the uncompressed images can be as big as 150MB, allocate ample swap space for the process.

    Q. What is an DOQQ ? A digital orthophoto quadrangle is a digital copy of an aerial photograph that has been geometrically corrected to have the metric qualities of a map. The South Carolina DOQQs cover an area equal to approximately 1/4 of a USGS quadrangle map, and are frequently referred to as a 3.75 minute DOQQs.

    Q. Who made the DOQQs ? This data was funded under a joint project between the State of South Carolina and the National Oceanic & Atmospheric Administrations. Acquisition and production of the imagery was conducted by a contractor to the US Geologic Survey.

    Q. How accurate are these DOQQs ? These DOQQs meet National Map Accuracy Standards for 1:12,000 scale.

    Q. When was this data collected ? During 1994. Exact dates for each image can be found in the metadata database available from the viewing page.

    Q. What can I do with a DOQQ ? DOQQ's make an excellent base map for generating other spatial data as well as an excellent medium for integrating and viewing other spatial data. DOQQ's are frequently used in natural resource management, planning, engineering, scientific research, and facilities and operations  management.

South Carolina Depatment of Natural Reasources - National Oceanic & Atmospheric Administration - Technology Planning & Management Corporation