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Landsat
Data
California Landsat Scenes |
Metadata | Data Location
| Creating JPEGs | Scenes Outside CA
California
Landsat Scenes |
The Branner Earth Sciences
Library has Landsat-7 Thematic Mapper
images for the entire state of California. Most
of the scenes were taken during the winter of 1999/2000
and have close to 0% cloud cover. Each scene
is a collection of about 300MB of data.
The individual Landsat
CDs also contain a "README.GTF" file (which
can be opened with any text editor) that has metadata
including a description of the Landsat naming convention.
For more
information about the Landsat-7 Mission and its products
vists the USGS Landsat-7
Homepage.
To view thumbnails of
the images, go to:
http://www.sdc.ucsb.edu/imagery_examples/L7/L7.html
For help
selecting the scene you want, reference the
grid below (click on the image to view a larger version)
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Lansdat-7 ETM+ Band Characteristics
Band
Number |
Spectral Range
(µ) |
Ground Resolution
(m) |
Data Lines
Per Scan |
Data Line
Length (bytes) |
Bits Per
Sample |
| 1 |
.450 to .515 |
30 |
16 |
6,600 |
8 |
| 2 |
.525 to .605 |
30 |
16 |
6,600 |
8 |
| 3 |
.630 to .690 |
30 |
16 |
6,600 |
8 |
| 4 |
.775 to .900 |
30 |
16 |
6,600 |
8 |
| 5 |
1.550 to 1.750 |
30 |
16 |
6,600 |
8 |
| 6* |
10.40 to 12.50 |
60 |
8 |
3,300 |
8 |
| 7 |
2.090 to 2.35 |
30 |
16 |
6,600 |
8 |
| 8 |
.520 to .900 |
15 |
32 |
13,200 |
8 |
*Values apply to both high-
and low-gain data. |
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Most of the state is available
on CD-ROM at Branner library. They are held at the circulation
desk under the call number G4361.A4 2000.E7. Please
specify the path and row number you need.
The remainder of the state
is available via FTP from UC Santa Barbara. Contact the
GIS Staff
to order any of the remaining California images.
These images are available
to Stanford affiliates only. Please don't send
e-mail requests if you don't meet this requirement.
How to create
a "real color" JPEG from Landast TM spectral
data using ArcView Image Analysis or Adobe Photoshop
Arcview | Adobe Photoshop
Using ArcView Image Analysis
Copy
the necessary files from the CD onto the hard drive.
For real color images, you need bands 1,2, and 3.
The band numbers are all the way at the end of a very
long file name, so you may have to scroll out. Look
for “_b10” etc.
Once
you have copied them over, right-click on each file
and choose “Properties” from the drop-down
list that comes up. At the bottom of this menu,
uncheck the “Read only” box.
Open
ArcView. Turn on the Image Analysis and TIFF extensions.
Open
a new view. Under the View menu choose “Add
themes” in order to bring in each of the three
bands. Change the Data Source Types” to “Image
Analysis Data.” This is important you won’t
be able to manipulate the files if you bring them
in as anything else.
When
asked, do NOT create pyramid layers for the images.
In
the Image Analysis menu select Stack Images (You need
lots of free disk space in order to perform this operation,
and it takes a few minutes).
Once
the stack operation is done, a new theme will appear.
Turn it on. It should look approximately like
the real world.
At
this point, you have a couple of options depending on
what kind of resolution you want. If you just
want a low resolution image, you can now immediately
export the image as a JPEG under the file menu.
If you want a nice, large, high resolution image,
you have one more step. Choose Theme>Save Image
As and change the file type to TIFF. This will
take a long time and create an enormous image.
If you want a high resolution JPEG then open this
large file in Adobe Photoshop and re-save it as a JPEG.
This will also take a few minutes. Now you should
have an image that you can work with in any graphics
program.
Using Adobe Photoshop
(on a PC)
- Open the image files
for bands 1,2, and 3.
- Make one of the images
active
- From the Window menu
choose "Show Channels"
- In the window that appers,
right click on the black triangle at the top left
corner. (This will reveal a secondary menu). Select
"Merge Channels."
- In the Merge Channels
window, select RGB color for Mode. The number of Channels
should be 3. Hit the OK button.
- In the Merge RGB Channels
window, use the pull-down menus to specify band 3
for Red, band 2 for Green, and band 1 for Blue. Hit
the OK button.
- The resultant image
can now be saved as a .jpeg or in a number of other
file formats.
| Scenes Outside California
|
Several websites provide access to Landsat imagery from
around the world. Global Land Cover Facility
is the one we use most often. Several other sites are linked from our
web data page.
USGS offers a Global Visualization Viewer where you
can browse images from several different satellite sensors(ASTER, EO-1, Landsat 1-7, MODIS).
Last modified:
July 21, 2006
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