| What
is a DOQQ? |
The answer to this question and other fundamental questions
about DOQQs can be found on the DOQQ
help page. |
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| When
will the entire state be covered?
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. |
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|
| 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. |
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|
| 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/ |
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|
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| 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.
|
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|
| 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. |
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| How
can I convert a JPEG2000 file into a TIFF file? |
Programs such as Adobe Photoshop are able to convert JPEG2000
files. |
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| 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. |
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| How
can I get the unrectified imagery? |
To be announced. |
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| 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. |
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| When
will the DOQQs be updated? |
To
be announced. |
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|