DOQQ 2004 Frequently Asked Questions Monday, April 4, 2005
What is a DOQQ?

The answer to this question and other fundamental questions about DOQQs can be found on the DOQQ help page.

   

When will the entire state be covered?

-and-

What areas of the state are covered?
The entire state will be covered as with the DOQQ 1998 images. When the state will be completed covered is yet to be determined.
   
Why are the DOQQs stored in the JPEG2000 format? The JPEG2000 format allows for the DOQQs to be compressed greatly without sacrificing the visual quality of the image. A 150 megabyte DOQQ can be compressed using 20 to 1 compression into a 7.5 megabyte JPEG2000 file. To the naked eye, there is very little change between the original image and the JPEG2000 image.
   
What is the JPEG2000 format?
"JPEG 2000 is the latest series of standards from the JPEG committee. The original standard for digital images (IS 10918-1, popularly referred to as JPEG) was developed 15 years ago, and with the major increase in computer technology since them, and lots of research, it was felt to be time for a new standard capable of handling many more aspects than simply making the digital image files as small as possible. JPEG 2000 uses 'wavelet' technology. and as well as being better at compressing images (up to 20 percent plus), it can allow an image to be retained without any distortion or loss. Simply sending the first part of such a 'lossless' file to a receiver can result in a lossy version appearing (like present JPEG) - but continuing to transmit the file results in the fidelity getting better and better until the original image is restored."
from http://www.jpeg.org/faq.phtml?action=show_answer&question_id=q3d5bc0701c9b6
 
For more information about JPEG2000, see the JPEG2000 web site at http://www.jpeg.org/
 
   
What programs can I use to view the JPEG 2000 files?

There are several ways to view a JPEG2000 image. One way is to use a GIS such as Intergraph Geomedia or ESRI ArcGIS that has native JPEG2000 support.

A second way is to download a plugin for a program that you are using. For example, search for Photoshop and JPEG2000 through a search engine such as Google, and you will find some plug-ins written by third parties for Adobe Photoshop.

Note: For ArcView 3.x users, it may be necessary to install an extension (a plugin for ArcView) to view JPEG2000. Click here to download a Winzip file with the necessary files to enable ArcView 3.x to view JPEG2000 files.

For Internet Explorer (IE) and Netscape users, there is a plugin for these browsers available at the LizardTech web site at http://www.lizardtech.com/download/dl_download.php?detail=geo_expressview_plugin&platform=win

For other plugins and JPEG2000 tools, use your favorite search engine using JPEG2000 as a keyword.

   
Are the JPEG2000 files for the DOQQ 2004 images registered to the earth's surface?

Yes. The Winzip file that you download from Atlas that contains a DOQQ 2004 JPEG2000 file will also contain a J2W World file. This file serves the same purpose as a tfw file does for a TIF file. It contains coordinate information for placement of the image on the surface of the earth. Also contained in the Winzip file is a csf file and a prj file that contain projection information for Intergraph Geomedia and ESRI GIS products for documenting the projection of the images.

The images are projected to the UTM 15 North NAD83 coordinate system with ground units in meters.

   
How can I convert a JPEG2000 file into a TIFF file? Programs such as Adobe Photoshop are able to convert JPEG2000 files.
   
I need a large number of DOQQs, and downloading the files will take forever! How I can get a CD with the DOQQs that I need? We are able to ship the 2004 DOQQs on DVDs for a fee. For more information, see our ordering page.
   
How can I get the unrectified imagery? To be announced.
   
Will decompressing the JPEG2000 file into a TIF file remove the loss from compression? No, the loss has already occurred. Again, in most cases, the loss is not noticable to the naked eye. Only those people interested in performing detailed data analysis should need the uncompressed files.
   
When will the DOQQs be updated? To be announced.