--- Begin Forwarded Message ---
Date: Thu, 7 Dec 2000 11:32:33 -0800
From: Jennifer Stone Muilenburg <[log in to unmask]>
Subject: Fw: Image Registration for DOQs available from Terraserver
Sender: Jennifer Stone Muilenburg <[log in to unmask]>



Check out this development from Terraserver. We tried this, and it works
great -- the only potentially problematic piece is that you can only grab 1m
photos in small chunks (much smaller than one doqq), but it will be
especially useful for folks using a small study area.

Jenny Stone Muilenburg
Geographic Information Systems Librarian
Map Collection, University of Washington Libraries
Box 352900   Seattle, WA 98195-2900
phone: 206.543.2725
[log in to unmask]


----- Original Message -----
From: <[log in to unmask]>
To: "UCGIS Community" <[log in to unmask]>
Sent: Thursday, December 07, 2000 10:36 AM
Subject: Image Registration for DOQs available from Terraserver


> Folks:
>
> Since mid-1998, Terraserver (terraserver.microsoft.com) has been serving
up
> millions of images each month from compressed USGS Digital OrthoPhoto
Quads
> (DOQs), Russian SPIN-2 imagery, and more, and recently the USGS
topographic
> maps in digital format (Digital Raster Graphics) and links to the USGS
> stream gaging stations from these DRGs.  The Microsoft TerraServer web
site
> is one of the world's largest online databases, with 20 terabytes of disk
> storage, allowing anyone to quickly and easily use maps and images to
> explore the United States and certain places around the world with a
> standard web browser.   An average of 40,000 users request 4,000,000
images
> from the site everyday.  This magnificent site grew out of a cooperative
> research and development agreement with Microsoft to compress Terrabytes
of
> images using MrSID compression routines.  Some images have been available
> for download and in all cases, for purchase.
>
> The DOQs have been useful in exposing a wide variety of users, mostly
> non-GIS users, to the power and utility of digital imagery of the
> landscape.  They have not been able to be used in GIS software directly
> from the Terraserver without the user placing them side-by-side with
vector
> data and usinig registration and rectification algorithms within these
> software packages... until now.
>
> Yes, that's right!  I'm pleased to report that when a user clicks on the
> "download" button, he or she has the option of downloading a header file!
> This will allow the user to directly use these images in a GIS package.
> This header file is a text file and should be saved with a .jgw extension
> [note that there is an error on the web page that indicates the wrong
> naming convention] with the base name the same as the image.   Therefore,
> if you download a "blair.jpg" image, you should name the header file
> "blair.jgw" so that your GIS software will read it.
>
> I tried this recently, downloading an image of Blair, Nebraska.  The DOQs,
> as most USGS data, are in UTM meters.  Then I downloaded USGS
100,000-scale
> digital line graph (DLG) roads data (from http://edcwww.cr.usgs.gov -
> WebGLIS - soon to be http://earthexplorer.usgs.gov) for the same area and
> overlaid the two.  They were offset as seen on the image attached,
> terraserveroff_sm.jpg.  Why were they offset?  The DOQs are cast on the
> North American Datum (NAD) of 1983 while the 100K DLGs are on NAD 1927.
>
> Thus, there is an offset if you use USGS DLGs and USGS DOQs together.  But
> - no problem!  You have several options.  One, measure the offset and
> adjust the header file (in my case, blair.jgw) according to the offset in
> the x and y directions.  I had to add 30 meters easting (x) and subtract
> 200 meters northing (y) which were the last 2 lines in the header file.
A
> second option is to use the tricon program to give you a conversion
between
> NAD 27 and NAD 83 which you can use to edit your header file, available
> from the bottom of the page http://rockyweb.cr.usgs.gov/software.  A third
> option is to use your GIS software's register and rectify commands to
> rubber-sheet your image to an established set of vector features, such as
> roads.  In the case of ArcView, you can use the K12 School Tools extension
> or the Image Analysis extension.
>
> I hope this is helpful!  It's a great day for GIS users, so spread the
> word!
>
> Joseph
> ----------------------------------------------------------------
> Joseph J. Kerski, Ph.D.
> Geographer - Education / GIS
> US Geological Survey
> Building 810 - Entrance W-5 - Denver Federal Center
> Box 25046 - MS 507
> Denver CO  80225-0046  USA
> [log in to unmask]
> Tel 303-202-4315
> Fax 303-202-4137
> http://rockyweb.cr.usgs.gov/public/outreach/
> USGS:  Science for a Changing World
> --------------------------------------------------------------
>
>
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