Advanced Spaceborne Thermal Emission and Reflection Radiometer -
Descending/Day (2000 - present)
Product includes Visible and Near Infrared (VNIR),
Thermal Infrared (TIR), and Shortwave Infrared (SWIR) bands;
VNIR is shown
Advanced Spaceborne Thermal Emission and Reflection Radiometer -
Ascending/Night (2000 - present)
Product includes Shortwave Infrared (SWIR) and
Thermal Infrared (TIR) bands;
TIR is shown
Advanced Spaceborne Thermal Emission and Reflection Radiometer -
Descending/Day - United States (2000 - present)
Product includes Visible and Near Infrared (VNIR),
Thermal Infrared (TIR), and Shortwave Infrared (SWIR) bands;
VNIR is shown
Advanced Spaceborne Thermal Emission and Reflection Radiometer -
Ascending/Night - United States (2000 - present)
Product includes Shortwave Infrared (SWIR) and
Thermal Infrared (TIR) bands;
TIR is shown
Landsat 4 - Present (MSS, TM, ETM+, and OLI (coming in 2013) Combined)
Yes *
* Landsat Archive Collection images may require
processing before being available to download. Those scenes
may be submitted for processing at no charge and
downloaded at no charge following a processing delay.
Scenes from the Landsat archive are available at no charge,
processed to Standard Terrain Correction (Level 1T). While
some scenes do not have the ground-control or elevation data
necessary to perform L1T correction,
the best level of correction is applied. More details at
Landsat Product Information.
TerraLook Global Land Survey 1975 Landsat 1-3 MSS (1972-1983)
No *
* TerraLook Collection images are not
directly downloadable, but the processed image collection
may be downloaded at no charge following a processing delay.
Note: Download available denotes that the actual data product is available
for download at no charge through GloVis.
About Browse Images
All of the USGS browse images are subsampled JPEGs of selected bands from the
actual sensor data. The band combination, stretch, and resolution of the browse
vary according to each sensor.
Scenes from the Landsat archive are processed to Standard Terrain Correction (Level 1T). While some scenes do not have the ground-control or elevation data necessary to perform L1T correction, the best level of correction is applied. More details at Landsat Product Information.
Within the Browse Image Viewer, the browse images are displayed in Lambert
Azimuthal Equal Area Projection unless otherwise noted.
ASTER Level-1A and Level-1B
The ASTER VNIR (Visible Near Infrared) browse images
are displayed as a 3N, 2,1 (RGB) color composite.
The ASTER TIR (Thermal Infrared) browse images are
displayed as a 13,12,10 (RGB) color composite. The TIR browses
displayed on GloVis are from selected night-acquired images.
VNIR and TIR bands may be available for day and night-acquisition
images; however, you need to review the metadata for each scene you
select to determine what bands are available for that scene.
GloVis provides a catalog of ASTER Level-1A browse images
for the entire world and ASTER Level-1B browse images for the U.S.
The following two data sets are orderable from GloVis:
ASTER Level-1A contains
reconstructed, unprocessed instrument digital numbers (DNs) derived
from the telemetry streams of the 3 telescopes: Visible Near
Infrared (VNIR), Shortwave Infrared (SWIR), and Thermal Infrared
(TIR).
ASTER Level-1B contains
radiometrically calibrated and geometrically co-registered data
over the United States
for all the channels acquired previously through the telemetry
streams of the 3 different telescopes in Level-1A.
Please refer to the
ASTER Policies page
for more information about ordering.
Users are advised that ASTER SWIR data acquired from late April 2008
to the present exhibit anomalous saturation of values and anomalous
striping. This effect is also present for some prior acquisition
periods. Please refer to the ASTER SWIR User Advisory Document for more details.
EO-1 ALI
The Advanced Land Imager (ALI) browse images are generated from the
Level 1 radiometrically corrected data and displayed as a 5,4,2
(RGB) band combination.
Pixels are subsampled to a resolution of 240 meters from the
original 30-meter data (a factor of 8 in each direction).
The exact scene length will vary. The two most typical scene
lengths will be approximately 42 km for a standard scene and
approximately 185 km for an extended scene.
Each band is linearly stretched between the 1% and 97% histogram
values.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 25K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 6K.
The original browse images (viewed in a separate browser window)
are Level 1 radiometrically corrected browse in satellite
orientation.
EO-1 Hyperion
The Hyperion browse images are generated from the Level 0 (raw)
data and displayed as a RGB (40:31:13) band combination.
Pixels are subsampled to a resolution of 120 meters from the
original 30-meter data (a factor of 4 in each direction).
The exact scene length will vary. The two most typical scene
lengths will be approximately 42 km for a standard scene and
approximately 185 km for an extended scene.
The Hyperion browses have had the dark calibration subtracted and
the gains have been applied. Each band is linearly stretched
between the 1% and 97% histogram values. The data is then scaled
from 12 bits to 8 bits.
For the full-resolution browse, the images are JPEG compressed
with an average file size of 25K. For the 1000 meter display mode,
the browse images are GIFS with an average file size of 2K.
The original browse images (viewed in a separate browser window)
are Level 1 radiometrically corrected browse in satellite
orientation.
GLS1975 (Landsat 1-3)
Images acquired from 1972-1983 are displayed as a 4,2,1
(RGB) color composite.
Pixels are subsampled to a resolution of 480 meters from the
original 80-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
GLS1975 (Landsat 4-5)
Images acquired from 1982-1987 are displayed as a 4,2,1
(RGB) color composite.
Landsats 4-5 MSS data has sparse coverage and was used only to fill
in gaps in coverage for the GLS1975 Landsat 1-3 dataset.
Pixels are subsampled to a resolution of 480 meters from the
original 80-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
GLS1990
Images acquired from 1987-1997 are displayed as a 5,4,3
(RGB) color composite.
Pixels are subsampled to a resolution of 480 meters from the
original 30-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
GLS2000
Images acquired from 1999-2003 are displayed as a 5,4,3
(RGB) color composite.
Pixels are subsampled to a resolution of 255 meters from the
original 30-meter data.
Each Landsat 7 scene is color-stretched based on individual
scene content. This may result in an apparent mismatch of
colors between scenes.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 147K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 8K.
Full-resolution GeoTiff data may be downloaded at no charge.
GLS2005
Images acquired from 2003 - 2008 are displayed as a 5,4,3
(RGB) color composite.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 147K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 8K.
Full-resolution GeoTiff data may be downloaded at no charge.
GLS2005 - Islands (EO-1)
Images acquired from 2004 - 2008 are generated from the
Level 1 radiometrically corrected data and displayed as a 5,4,2
(RGB) band combination.
Pixels are subsampled to a resolution of 240 meters from the
original 30-meter data (a factor of 8 in each direction).
The exact scene length will vary. The two most typical scene
lengths will be approximately 42 km for a standard scene and
approximately 185 km for an extended scene.
Each band is linearly stretched between the 1% and 97% histogram
values.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 25K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 6K.
The original browse images (viewed in a separate browser window)
are Level 1 radiometrically corrected browse in satellite
orientation.
Full-resolution GeoTiff data may be downloaded at no charge.
GLS2010
Images acquired from 2008 - 2011 are displayed as a 5,4,3
(RGB) color composite.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 147K. For the 1000 meter display
mode, the browse images are GIFs with an average file size of 8K.
Full-resolution GeoTiff data may be downloaded at no charge.
GLS2010 - Islands (EO-1)
Images acquired from 2009 - 2011 are generated from the
Level 1 radiometrically corrected data and displayed as a 5,4,2
(RGB) band combination.
Pixels are subsampled to a resolution of 240 meters from the
original 30-meter data (a factor of 8 in each direction).
The exact scene length will vary. The two most typical scene
lengths will be approximately 42 km for a standard scene and
approximately 185 km for an extended scene.
Each band is linearly stretched between the 1% and 97% histogram
values.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 25K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 6K.
The original browse images (viewed in a separate browser window)
are Level 1 radiometrically corrected browse in satellite
orientation.
Full-resolution GeoTiff data may be downloaded at no charge.
Landsat 1-5 Multispectral Scanner (MSS)
For Landsat 4 and 5 MSS, the images are displayed as RGB
composites, bands 4, 2, and 1, with a 2% linear stretch. For
Landsat 1, 2, and 3 MSS, the RGB composites are created from bands
7, 5, and 4.
Images are resampled to a pixel size of 240 meters from the
original nominal 80-meter data.
In the full resolution browse view, the MSS images may appear to be
one-fourth the size of the Landsat 7 browse images because of the
processing used to create the browse, but the actual MSS scene will
cover approximately the same area (185 x 170 km).
The full-resolution browse images are displayed as JPEG compressed
files with an average file size of ~50K. For the 1000-meter display
mode, the browse images are GIFs with an average file size of ~35K.
Landsat 4-5 Thematic Mapper (TM)
The images are displayed as RGB composites, bands 5, 4, and 3, with
2% linear stretch applied.
Images are resampled to a pixel size of 240 meters from the
original 28.5-meter data.
In the original resolution browse view, the Landsat 4 and 5 browse
images may appear to be one-fourth the size of the Landsat 7 browse
images because of the processing used to create the browse, but the
actual TM scene will cover approximately the same area (183 x 170
km).
The full-resolution browse images are displayed as JPEG compressed
files with an average file size of ~50K. For the 1000-meter display
mode, the browse images are GIFs with an average file size of ~35K.
The original browse previews that are used to create the
full-resolution browse images are uncorrected images in satellite
orientation, and they can be viewed in a separate window.
Landsat 4 - Present (MSS,
TM, ETM+, and OLI (coming in 2013) Combined)
These images are from Landsat 8 OLI (coming in 2013),
Landsat ETM+, Landsat ETM+ SLC-off, Landsat
TM, and Landsat 4 and 5 MSS - all the Landsat sensors that utilize
World Reference Ssystem-2 (WRS-2). The scenes are merged together
in chronological order to enable easy browsing through the various
sensors. Scenes from any of the sensors can be searched, previewed,
and ordered simultaneiously.
When an image is selected, it is outlined by a color that is unique
to each sensor.
Dataset
Color
Landsat OLI (coming in 2013)
Orange
Landsat ETM+
Blue
Landsat ETM+ SLC-off
Green
Landsat TM
Yellow
Landsat 4 - 5 MSS
Red
Because of the large quantity of scenes for the combined datasets,
loading the inventory will be very time consuming when using dialup
internet or other slow connections.
For details on the individual Landsat sensors, please refer to the
specific sensor information above.
When scenes are added to the combined sensor scene list, they will
also be added to the scene list for that corresponding sensor.
Conversely, adding scenes to the list for an individual sensor will
be reflected in the combined sensor scene list. All other scene
list features will be handled in the same way.
Landsat 7 Enhanced Thematic Mapper Plus
(ETM+)
Images acquired from June 1999 - May 2003 are displayed as RGB
composites, bands 5, 4, and 3.
Images are resampled to a pixel size of 240 meters from the
original 30-meter data.
Each Landsat 7 scene is color-stretched based on individual scene
content. This may result in an apparent mismatch of colors between
scenes.
The full-resolution browse images are displayed as JPEG compressed
files with an average file size of ~130K. In the 1000-meter display
mode, the browse images are GIFs with an average file size of ~35K.
The original browse previews that are used to create the
full-resolution browse images are uncorrected images in satellite
orientation, and they can be viewed in a separate window.
Landsat 7 Enhanced Thematic
Mapper Plus (ETM+) Scan Line Corrector Off (SLC-Off)
Images acquired after July 2003 are displayed as RGB composites,
bands 5, 4, and 3. Landsat 7 ETM+ scenes acquired from 5/31/03 -
7/14/03 and 9/3/03 - 9/17/03 are not available.
Images are resampled to a pixel size of 180 meters from the
original 30-meter data.
The "Show Browse" option displays an overlay that illustrates the
approximate extent of the SLC-off image gaps.
Each Landsat 7 scene is color-stretched based on individual scene
content. This may result in an apparent mismatch of colors between
scenes.
The full-resolution browse images are displayed as JPEG compressed
files with an average file size of ~130K. In the 1000-meter display
mode, the browse images are GIFs with an average file size of ~35K.
The original browse previews that are used to create the
full-resolution browse images are uncorrected images in satellite
orientation, and they can be viewed in a separate window.
When ordering this data, a Warning Box will pop up as a reminder
that you are attempting to order SLC-off data.
For more information on SLC-Off data, please see the
Landsat FAQ.
Landsat 8 Operational Land Imager (OLI)
(coming in 2013)
Landsat 8 is scheduled to launch in February, 2013. OLI
images will be available in GloVis following an operational
verification and validation period. See the
Landsat
website for more information.
MODIS
The images are displayed as a 1,4,3 (RGB).
The images generally cover a 10° x 10° area.
Pixels are subsampled to a resolution of approximately 10
kilometers from the original 5 kilometer data.
Each scene is color-stretched based on individual scene content.
This may result in an apparent mismatch of colors between scenes.
The 10 kilometer display browse images are jpgs with an average
file size of 5K. The full-resolution browse images are JPEG
compressed with an average file size of 30K.
The full-resolution browse images, which can be viewed in a
separate browser-window, are the same as the 5-kilometer images
shown in the applet. The only exception are datasets that have
an annotation on the bottom of the browse. These browse images
will cover more area than what is shown in the applet.
The browse are displayed in the sinusoidal projection.
MRLC 2001 Terrain Corrected (TC) and
2001 Reflectance Adjusted (RA)
The images are Landsat 7 ETM+ and Landsat 4-5 TM images and do not
show the final MRLC product. They display as a 5,4,3 (RGB)
composite.
Pixels are subsampled to a resolution of 240 meters from the
original 30 meter data.
Each landsat 7 scene is color-stretched based on individual scene
content. This may result in an apparent mismatch of colors between
scenes.
For the full-resolution browses, the image are JPEG compressed with
an average file size of ~130K. For the 1000 meter display mode, the
browse images are GIFs with an average file size of ~35K.
The original browse images (viewed in a separate browser window) are
raw browse in satellite orientation.
Full-resolution MRLC 2001 Terrain Corrected data may be downloaded
at no charge.
National Aerial Photography Program (NAPP)
NAPP browse images are created from medium resolution digital
products that are captured by a digital camera. The browse files
are resampled to 72 dpi.
NAPP scenes cover approximately a 5.5 x 5.5 mile area.
NAPP browse on GloVis have been clipped to remove the excess film
margins and the images have been oriented "north up".
Some browse may contain the Moiré pattern artifact.
The Moiré pattern artifact is a pattern in areas where
the spatial frequency of the land area is higher than detector
density on the focal plane in the digital camera used to
capture the image. The artifact that results is a type of
aliasing known as moiré patterns or moiré waves.
This well-known artifact is not an error in the original film
or the digitizing process. The moiré pattern shown in
some of the browse is not present when scanned at
high-resolution on photogrammetric quality scanners used at the
Earth Resources Observation and Science Center (EROS). For more
information on this artifact, check these web sites:
http://www.dpreview.com/learn/?/Glossary/Digital_Imaging/Moire_01.htm
http://www.maxim-ic.com/appnotes.cfm/appnote_number/928
North American Landscape Characterization (NALC)
The browse images are Landsat 4 and 5 MSS browse images displayed
as RGB composites, bands 4, 2, 1, with a 2% linear stretch.
Images are resampled to a pixel size of 480 meters from the original
nominal 60-meter data.
The full-resolution browse images are displayed as JPEG compressed
files with an average file size of ~50K. For the 1000-meter display
mode, the browse images are GIFs with an average file size of ~35K.
The registration of the images in GloVis is inaccurate, however the
original data registration is accurate.
Full-resolution data may be downloaded at no charge.
North American Landscape Characterization (NALC) data consists of
Landsat Multi-Spectral Scanner (MSS) time-series triplicates that
were acquired in 1973, 1986, and 1991 (+/- one year).
National High Altitude Photography (NHAP)
NHAP browse images are created from medium resolution digital
products that are captured by a digital camera. The browse files
are resampled to 72 dpi.
NHAP scenes for Color Infrared (CIR) cover approximately an 8 x 8
mile area and Black and White (B/W) cover approximately an 11 x 11
mile area.
NHAP browse on GloVis have been clipped to remove the excess film
margins and the images have been oriented "north up".
Some browse may contain the Moiré pattern artifact.
The Moiré pattern artifact is a pattern in areas where
the spatial frequency of the land area is higher than detector
density on the focal plane in the digital camera used to
capture the image. The artifact that results is a type of
aliasing known as moiré patterns or moiré waves.
This well-known artifact is not an error in the original film
or the digitizing process. The moiré pattern shown in
some of the browse is not present when scanned at
high-resolution on photogrammetric quality scanners used at the
Earth Resources Observation and Science Center (EROS). For more
information on this artifact, check these web sites:
http://www.dpreview.com/learn/?/Glossary/Digital_Imaging/Moire_01.htm
http://www.maxim-ic.com/appnotes.cfm/appnote_number/928
Systematic ETM+
The Level 1G (L1G) data product provides systematic radiometric
and geometric accuracy, which is derived from data collected
by the sensor and spacecraft.
The original browse images (viewed in a separate browser window)
were rotated, aligned, and georeferenced to UTM map projection.
Geometric accuracy of the systematically corrected product should
be within 250 meters (1 sigma) for low-relief areas at sea level.
These were used as input to the Tri-Decadal data set so they only
cover the time period from June 29, 1999 to May 31, 2003.
TerraLook
The TerraLook product is a user-selectable collection of simulated
natural-color, JPEG-compressed satellite images. The TerraLook
collection consists of georegistered Advanced Spaceborne Thermal
Emission and Reflection Radiometer (ASTER) images and Global
Land Survey (GLS) images from five epochs (circa 1975,
1990, 2000, 2005, and 2010).
The TerraLook product is delivered as a single zip file using ftp.
The same browse images are used for the TerraLook product and for
the Aster and GLS products. See the descriptions of the
ASTER and GLS
browse images for more information.
The browse images use different band combinations and stretches
than are used in the TerraLook product. As a consequence, the
browse images will not look the same as the TerraLook product.
The Tri-Decadal Global Landsat Orthorectified (previously Landsat
Orthorectified) ETM+ browse images are displayed as a 5,4,3 (RGB)
color composite.
Pixels are subsampled to a resolution of 240 meters from the
original 30-meter data.
Each Landsat 7 scene is color-stretched based on individual
scene content. This may result in an apparent mismatch of colors
between scenes.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 147K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 8K.
The original browse images (viewed in a separate browser window)
are raw browse in satellite orientation.
Full-resolution data may be downloaded at no charge.
Tri-Decadal ETM+ Pan (1999-2003)
The Tri-Decadal Global Landsat Orthorectified (previously Landsat
Orthorectified) ETM+ Pan browse images are displayed as a 7,4,2
(RGB) color composite.
Pixels are subsampled to a resolution of 240 meters from the
original 30-meter data.
Each Landsat 7 scene is color-stretched based on individual
scene content. This may result in an apparent mismatch of colors
between scenes.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 147K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 8K.
The original browse images (viewed in a separate browser window)
are raw browse in satellite orientation.
Full-resolution data may be downloaded at no charge.
Tri-Decadal ETM+ Pan Mosaics
The Tri-Decadal Global Landsat Orthorectified ETM+ Pan Mosaic
browse images are displayed as a 7,4,2 (RGB) color composite.
Pixels are subsampled to a resolution of 285 meters from the
original 30-meter data.
The mosaics cover a 5 degree (north-south) segment of a standard 6
degree wide (east-west) UTM zone. It is further subdivided into
four 2.5 degree by 3 degree quadrants.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
Tri-Decadal TM (1987-1997)
The Tri-Decadal Global Landsat Orthorectified (previously Landsat
Orthorectified) TM browse images are displayed as a 7,4,2 (RGB)
color composite.
Pixels are subsampled to a resolution of 480 meters from the
original 30-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
Tri-Decadal TM Mosaics
The Tri-Decadal Global Landsat Orthorectified TM Mosaic browse
images are displayed as a 7,4,2 (RGB) color composite.
Pixels are subsampled to a resolution of 700 meters from the
original 30-meter data.
The mosaics cover a 5 degree (north-south) segment of a standard 6
degree wide (east-west) UTM zone.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
Tri-Decadal MSS 4-5 (1982-1987)
The Tri-Decadal Global Landsat Orthorectified (previously Landsat
Orthorectified) MSS 4-5 browse images are displayed as a 4,2,1
(RGB) color composite.
Landsats 4-5 MSS data has sparse coverage and used only to fill in
gaps in coverage for the Tri-Decadal MSS 1-3 dataset.
Pixels are subsampled to a resolution of 480 meters from the
original 80-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
Tri-Decadal MSS 1-3 (1972-1983)
The Tri-Decadal Global Landsat Orthorectified (previously Landsat
Orthorectified) MSS 1-3 browse images are displayed as a 7,5,4
(RGB) color composite.
Landsats 1-3 MSS data provide worldwide historical coverage.
Pixels are subsampled to a resolution of 480 meters from the
original 80-meter data.
For the full-resolution browses, the images are JPEG compressed
with an average file size of 38K. For the 1000 meter display mode,
the browse images are GIFs with an average file size of 23K.
The original browse images (viewed in a separate browser window)
were generated from full-resolution data that is orthorectified
and UTM-projected, using the World Geodetic System 1984 datum.
Full-resolution data may be downloaded at no charge.
NOTE: Because the browse images are processed from raw uncorrected data, the
positional accuracy of the scenes can only be expected to be accurate within a
few pixels at full resolution. These browse images are not intended for
analytical use, but only as a visual scene selection aid.
Q: How is the cloud cover calculated,
and why are some scenes cloudy when the cloud cover is reported
to be 0%?
A: The cloud cover index is an automated calculation which may
provide a useful estimate, but the algorithm is not always accurate when it
encounters snow, ice, water, or other unusual scene content. Haze, thin
clouds, and small clouds ("popcorn") can frequently be missed in the cloud
cover assessment.
Q: Why are some Landsat scenes
"missing"?
A: GloVis displays most of the Landsat scenes, but some are not
available through this tool. Please refer to the
Landsat
FAQ for details on searching for and ordering Landsat scenes.
Q: Can I find the actual
gain and bias values for a Landsat scene on GloVis?
A: No, you will not find the actual gain and bias values on GloVis.
Gain and bias values can only be obtained when actual data is ordered
because to gain and bias values are only available in the final product
metadata. These coefficients can then be applied with the DN values within
the imagery to convert to accurate radiance values.
For information on gain and bias values, please refer to the
Landsat
FAQ.
Q: Where can I find out more about
Landsat MSS, TM, and ETM+ data?
A: Please refer to the
Landsat
FAQ for information about all of the Landsat missions.
Q: Does red in ASTER images always represent
vegetation?
A: Red colors in the VNIR images generally represent vegetation.
Q: Why do some ASTER images have a
'smeared' line in them?
A: Images with smeared lines generally indicate a temporary
detector-related problem during the course of acquisition. They are
infrequent and irreversible. They generally result in a data gap on the
image. Depending on the amount of area affected and your application needs,
you may want to find an alternative scene.
Q: Why are some ASTER images
completely white?
A: Completely white, or nearly completely white, browse images
exist because saturated cloud cover leaves little to no useful image data.
Q: Why does the EO-1 Scene ID list a
path and row that is different than the path and row of the center part
of the image?
A: EO-1 imagery is collected based on a targeted center point. The
path and row listed in the Scene ID represents when the EO-1 instruments
began imaging, even though the target point may fall in the next row. In
the diagram below, the coordinates for Target 2 fall within the WRS row
below that of the coordinates for Target 1. However, since the instruments
began imaging Target 1 and Target 2 in the same path/row, both images would
have the same Target WRS path and Target WRS row in the
Scene ID. EO-1 is not able to image both targets on the same date;
therefore, the difference in the Scene IDs would show up in the Julian day
of acquisition.
Q: If NAPP scenes cover a square area,
why do they appear rectangular in GloVis?
A: NAPP browse images are provided in a geographic projection with
pixels that are not square in geographic coordinates. To be properly
displayed in GloVis, the browse images are resized to make the pixels
square in geographic coordinates. The result is that the browse images
end up being rectangular.
Q: When I download a NALC
dataset, will I receive all of the images for that triplicate?
A: Yes, all of the images available in the NALC triplicate will be
included in the downloaded product, even though only a
single browse image is displayed in GloVis.
Several application-specific questions are answered on the
Image Viewer Help page.
Contact Customer Services
Customer Services
U.S. Geological Survey
Earth Resources Observation & Science Center (EROS)
47914 252nd Street
Sioux Falls, SD 57198-0001
Tel: 800-252-4547
Tel: 605-594-6151
Fax: 605-594-6589
Email: custserv@usgs.gov
Business Hours: Monday thru Friday, 8:00 a.m. to 4:00 p.m., central time
U.S. Department of the Interior |
U.S. Geological Survey