• Product Description
• Comparison of NLAPS and LPGS Processing
• Prices
• Bulk Discount
• Search & Order
• Image Previews
• Sample data

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Product Description

The Landsat Enhanced Thematic Mapper Plus (ETM+) is a sensor carried onboard the Landsat 7 satellite and has acquired images of the Earth nearly continuously since July 1999, with a 16-day repeat cycle. An instrument malfunction occurred on May 31, 2003; as a result, all Landsat 7 image data acquired from July 14, 2003 (20:32:40 GMT) to the present were collected in SLC-off mode. Image data acquired from 5/31/03 (21:42:35 GMT) to 7/14/03 (20:32:40 GMT) and from 9/3/03 (01:32:15 GMT) to 9/17/03 (06:22:27 GMT) are not available for search and order.

On April 1, 2007, the Landsat 7 mission began imaging in an alternate mirror-scanning control mode from the original Scan Angle Monitor (SAM) process that has been used since the satellite was launched in 1999. This change, known as Bumper Mode, is necessary due to a predictable physical wear of the mirror bumpers mounted within the Enhanced Thematic Mapper Plus (ETM+) imaging system. Landsat 7 data users should notice little or no change as a result of this transition. Five years ago, the Landsat 5 Thematic Mapper (TM) scanner was successfully converted to this alternate imaging mode, and customers have reported no problems related to that change.

Landsat ETM+ image data consist of eight spectral bands (band designations), with a spatial resolution of 30 meters for bands 1 to 5 and band 7. Resolution for band 6 (thermal infrared) is 60 meters and resolution for band 8 (panchromatic) is 15 meters. Approximate scene size is 170 km north-south by 183 km east-west (106 mi by 114 mi).

For all Landsat 7 ETM+ data (including SLC-off products), the following levels of correction are available to the general public.

• For all Landsat 7 ETM+ data (including SLC-off products), the following levels of correction are available to the general public.

  • Raw Uncorrected (Level 0Rp) (SLC-on and SLC-off) The Level 0Rp (L0Rp) data product provides reformatted raw data with no radiometric or geometric correction applied. Reformatting includes shifting pixels by integer amounts to account for 1) the alternating forward-reverse scanning pattern of the sensor, 2) the odd-even detector arrangement within each band, and 3) the detector offsets inherent to the focal plane array engineering design. The pixels are NOT aligned per scan line. Image data are stored as 8-bit unsigned integer (DN) values. Raw uncorrected (L0Rp) data are processed through the Landsat Archive Manager (LAM) and will have no map projection or datum assigned. L0Rp data are in HDF format and distributed on CD, DVD, or via FTP download. The SLC-off product includes the original duplicated scan lines along the edge of the scene. Please click here for more information on SLC-off L0Rp data.
  • Radiometric Corrected (Level 1R) (SLC-on and SLC-off) The Level 1R (L1R) data product provides radiometrically corrected L0R data where calibration is applied, but geometric correction is not applied. Scan lines are reversed, but the pixels are NOT aligned per scan line. Image data are not geometrically corrected or geographically referenced and are provided in 16-bit (radiance) values. All Level 1R products are processed by the Level 1 Product Generation System (LPGS).
  • Systematic Correction (Level 1G) (SLC-on and SLC-off) The Level 1G (L1G) data product provides systematic radiometric and geometric accuracy, which is derived from data collected by the sensor and spacecraft. The scene will be rotated, aligned, and georeferenced to a user-specified map projection. Geometric accuracy of the systematically corrected product should be within 250 meters (1 sigma) for low-relief areas at sea level. The SLC-off product includes the original data gaps. Duplicated pixels have been replaced with null values (zero-fill) and the image therefore contains alternating "stripes" of missing data. A scan gap mask is included with the final product. Please click here for more information on SLC-off Level 1G data. Level 1G SLC-on products are processed by the Level 1 Product Generation System (LPGS) or the National Land Archive Production System (NLAPS). Level 1G SLC-off products are processed by the Level 1 Product Generation System (LPGS).
  • Gap-filled (Level 1G) (SLC-off only) A gap-filled SLC-off product is a derived product in which all missing image pixels in the original SLC-off image have been replaced with estimated values based on one or more histogram-matched scene(s) from a previous date. The primary (SLC-off) and fill (SLC-off and/or SLC-on) scenes are radiometrically and geometrically corrected using the satellite model and platform/ephemeris information. All images are rotated and aligned to the user-specified map projection. The primary scene is co-registered to the fill scene(s) and all missing image pixels in the primary scene are then replaced with estimated values based on local linear histogram-matched data from the fill scene(s). A scan gap mask is generated for each band of the primary scene, which identifies the original data source for every pixel within the final output product. The delivered data product consists of the final gap-filled image, along with a gap mask (one file per band). For more information on gap-filled products and processing see the Landsat 7 SLC-off gap-filled product description. A scan gap mask is included with the final product (Detailed Description). Level 1 SLC-off gap-filled products are processed by the Level 1 Product Generation System (LPGS).
  • Standard Terrain Correction (Level 1T) (SLC-off only) The Level 1T (L1T) data product provides systematic radiometric and geometric accuracy by incorporating ground control points, while also employing a Digital Elevation Model (DEM) for topographic accuracy. Geodetic accuracy of the product depends on the accuracy of the ground control points and the resolution of the DEM used. The Standard L1T product is a processed dataset that will be available for download from USGS EROS. This dataset will include ETM+ SLC-off scenes that are over North America, have a quality score of 9, and have 10 percent or less cloud cover for data acquired prior to October 1, 2007 and 20 percent or less cloud cover for data acquired after October 1, 2007. The scenes will be processed based on the following parameters:

    Pixel Size	15m/30m/60m
    Media Type	CD/DVD/Download
    Output Format	GeoTIFF
    Map Projection	UTM only
    Orientation	NUP
    Resampling Method	CC

• The distribution of Landsat 7 ETM+ Terrain correction data is restricted to the U.S. Government and its affiliated users. Please contact USGS EROS Customer Services if you have questions regarding this policy.

  • Systematic Terrain Correction (Level 1Gt) (SLC-on and SLC-off) The Level 1Gt (L1Gt) data product provides systematic radiometric and geometric accuracy, while also employing a Digital Elevation Model (DEM) for topographic accuracy. The SLC-off product includes the original data gaps. Duplicated pixels have been replaced with null values (zero-fill) and the image therefore contains alternating "stripes" of missing data. A scan gap mask is included with the final product. Level 1Gt SLC-on products are processed by the Level 1 Product Generation System (LPGS) or the National Land Archive Production System (NLAPS). Level 1Gt SLC-off products are processed by the Level 1 Product Generation System (LPGS).
  • Terrain Correction (Level 1T) (SLC-on and SLC-off) The Level 1T (L1T) data product provides systematic radiometric and geometric accuracy by incorporating ground control points, while also employing a Digital Elevation Model (DEM) for topographic accuracy. Geodetic accuracy of the product depends on the accuracy of the ground control points and the resolution of the DEM used. The SLC-off product includes the original data gaps. Duplicated pixels have been replaced with null values (zero-fill) and the image therefore contains alternating "stripes" of missing data. A scan gap mask is included with the final product. Level 1T SLC-on products are processed by the Level 1 Product Generation System (LPGS) or the National Land Archive Production System (NLAPS). Level 1T SLC-off products are processed by the Level 1 Product Generation System (LPGS).
  • Gap-filled (Level 1Gt or 1T) (SLC-off only) A gap-filled SLC-off product is a derived product in which all missing image pixels in the original SLC-off image have been replaced with estimated values based on one or more histogram-matched scene(s) from a previous date. The primary (SLC-off) and fill (SLC-off and/or SLC-on) scenes are radiometrically and geometrically corrected using the satellite model and platform/ephemeris information. All images are rotated and aligned to the user-specified map projection. The primary scene is co-registered to the fill scene(s) and all missing image pixels in the primary scene are then replaced with estimated values based on local linear histogram-matched data from the fill scene(s). A scan gap mask is generated for each band of the primary scene, which identifies the original data source for every pixel within the final output product. The delivered data product consists of the final gap-filled image, along with a gap mask (one file per band). For more information on gap-filled products and processing see the Landsat 7 SLC-off gap-filled product description. A scan gap mask is included with the final product (Detailed Description). Level 1 SLC-off gap-filled products are processed by the Level 1 Product Generation System (LPGS).

• The distribution of Landsat 7 ETM+ Segment-based Gap-filled data is restricted to the U.S. Government and its affiliated users. Please contact USGS EROS Customer Services if you have questions regarding this policy.

  • Level 1T Terrain Corrected Segment-Based Gap-filled (LPGS) This Level 1T (L1T) product (includes systematic radiometric and geometric accuracy by incorporating ground control points, while also employing a Digital Elevation Model for topographic accuracy) incorporates a multi-scale segmentation model to fill the gaps in the SLC-off image. The segmentation model is based on terrain-corrected ETM+ SLC-on data from circa 2000. The gaps are filled with the same-day radiometric values using a nearest neighbor algorithm, while maintaining the landscape patterns derived from the segmentation model. Data products include the following parameters:

    Pixel Size	14.25m/28.5m/57m
    Media Type	CD/DVD/FTP
    Output Format	GeoTIFF, FAST-L7A, HDF
    Map Projection	UTM
    Orientation	NUP (MAP)
    Resampling Method	CC, NN, MTF

For all levels of correction, the following processing parameters are customer-defined:

*Other options may be available upon request.

Additional Information:

• Landsat Homepage
• Landsat FAQs
• Landsat 7 Science Data Users Handbook
• Technical Information (CPFs, definitive ephemeris)
• Project Documentation
• Landsat 7 SLC-off Data Products
• ETM+ Abstract

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Comparison of NLAPS and LPGS Processing

There are two separate processing systems used to generate USGS Landsat 7 ETM+ Level 1 products:

Level 1 Product Generation System (LPGS) - Level 1R, Level 1G, Level 1Gt and Level 1T products.

National Land Archive Production System (NLAPS) - Level 1G, Level 1Gt, and Level 1T products.

The overall capabilities of the LPGS and NLAPS processing systems are very similar. However, please be aware of these differences in the Level 1G, 1Gt, and 1T products of the two systems:

• LPGS does not trim scenes edges (NLAPS trims jagged scene edges).
• LPGS aligns bands to pixel centers (NLAPS uses pixel edges).
• Only the Calibration Parameter File will be available for radiometric correction.

For a detailed comparison of the product characteristics, see: Comparison of NLAPS and LPGS

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Prices

SLC-on data products (acquisition dates prior to May 31, 2003):

SLC-off data products (acquisition dates from July 25, 2003 to present):

Please contact USGS EROS Customer Services to gain approval for ordering terrain corrected data.

• Payment Options
• Handling Charge
• International Shipping
• Product Return Policy
• Delivery Times
• Priority Service

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Bulk Discount

A bulk discount of 20 percent off the standard product price will be applied to orders containing 25 or more single Landsat scenes (any combination of MSS, TM, and ETM+ SLC-on are allowed). No discounts are available for L7 ETM+ SLC-off, or ETM+ Gap-filled products.

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Search & Order

* Landsat Archive Manager

All Landsat ETM+ scenes in the USGS archive can be searched by geographic location using Earth Explorer or the USGS Global Visualization Viewer (GloVis). Only scenes with browse capability can be searched and ordered on GloVis. All Landsat 7 ETM+ data are referenced to WRS-2, the Worldwide Reference System of paths and rows.

New Landsat ETM+ scenes generally become available for search and order within 6 to 24 hours after data acquisition. To view real-time acquisitions of Landsat over the United States, please visit EarthNow!

Some Landsat 7 ETM+ scenes of areas outside the United States are not archived or distributed by USGS EROS. These scenes may be available from International Ground Stations (IGSs). IGS data are not products of USGS EROS and therefore prices, available formats, and processing options may vary according to the data provider. Metadata for most of the IGS-downlinked scenes is searchable through Earth Explorer.

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Image Previews

Landsat ETM+ scenes should always be previewed prior to purchase. Browse images of available scenes may be viewed by searching on Earth Explorer or GloVis.

Each Landsat ETM+ browse image is a resampled JPEG of the raw scene data. The browse image will be displayed as a 5,4,3 (RGB) composite with a 2% linear color stretch, based on individual scene content.

The image preview for SLC-off data includes an overlay and numerical grid that illustrates the approximate extent of the SLC-off image gaps.

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Sample Data

Landsat 7 ETM+ product samples are available for download at the Landsat Sample Products Web page.

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U.S. Department of the Interior | U.S. Geological Survey
URL: http://eros.usgs.gov/
Page Contact Information: custserv@usgs.gov
Page Last Modified: August 22, 2006