Landsat Data

Landsat Intro

Set up a free account with USGS.  Download at no charge from three locations, which all act a little differently and may show different coverage.

Do not get  LANDSAT 8 SURFACE REFLECTANCE CODE (LASRC) PRODUCT.

• LandsatLook Viewer.  Probably the best option.
  • Must zoom in the see the data; scale shows in lower left corner of the screen.
  • View scenes, with some contrast enhancement, with option to download
  • View cart with option in the upper left of the data table
  • May be a limit on how many files you can get at a time
• EarthExplorer --at one point not appear to have current Landsat 8 data
• GloVis (requires Java to run)
  • File menu has Option to download all the browse images for a scene, which you can rapidly cycle through with the Windows Image Viewer
  • If there are multiple scenes on screen, you can click on them to get the outline, and then use the Prev Scene and Next Scene in the lower left corner to advance
  • Landsat 8 data does not show unless you specifically check it, and then may be unreliable.

If you have trouble getting the right scene to cover the area you want:

• Go to https://landsat.usgs.gov/wrs-2-pathrow-latitudelongitude-converter  and enter the lat/long .
• Then note the path row, and when you get the Landsat data, insure you have the correct path and row, which are listed in the download table.

The Bulk Data Application (BDA) can manage downloads of multiple files.

Compress/Decompress has an option to uncompress files from USGS (Unix tar.gz file), and place them in a directory with the file name.  You must extract the Geotiff files to use in MICRODEM.

MICRODEM relies on the file naming convention from USGS.  It can currently deal with two variants, but not the  LANDSAT 8 SURFACE REFLECTANCE CODE (LASRC) PRODUCT.

MICRODEM will create the following subfolders in the directory with a Landsat scene if you attempt any computation analysis:

• band_hist: databases with the frequency histograms, one per band.
• multi_grids: grids with the data in MICRODEM DEM format, used for rapid loading for numerical calculations.
• princ_componenets: the principal components image in MICRODEM DEM format, one file for each component computed.
• unsup_class: unsupervised classification, in MICRODEM DEM format, a VAT file, and metadata.

Browse images.  The browse images are subsets of the full scenes, about 800x800 pixels and 130 kb in JPEG format.  You can create a database to view them.  They are not registered and you cannot do any mapping or analysis operations with them.

Look images.  You can use the look images, if you download them with the world file (.world extension).  You must then use File Tools Identify directory, and set the directory to have the correct projection.  Look images are full scale scenes with 30 m pixel size, and about 8000x8000 pixels and 6 MB in size.  This has been tested with the south polar stereographic files, but should also work with UTM.

Key Remote Sensing Options in MICRODEM

Landsat online viewers

• http://changematters.esri.com/compare compare two scenes from predetermined time periods, and see change in NDVI.
• Current Landsat (mostly Landsat 8) at https://aws.amazon.com/blogs/aws/start-using-landsat-on-aws/

Last revision 8/21/2017