Landsat

Since 1972 these satellites have provided epetitive, synoptic, global coverage of high resolution multispectral imagery. The characteristics of the MSS and TM bands were selected to maximize their capabilities for detecting and monitoring different types of Earth resources. For example, TM band 2 can detect green reflectance from healthy vegetation, and band 3 of TM is designed for detecting chlorophyll absorption in vegetation.

TM band 4 is ideal for near-IR reflectance peaks in healthy green vegetation and for detecting water-land interfaces. TM band 1 can penetrate water for bathymetric mapping along coastal areasand is useful for soil-vegetation differentiation and for distinguishing forest types. The two mid-IR red bands on TM (bands 5 and 7) are useful for vegetation and soil moisture studies, and discriminating between rock and mineral types. The thermal IR band on TM (band 6) is designed to assist in thermal mapping, and for soil moisture and vegetation studies.

Typically, TM Bands 4, 3, and 2 can be combined to make false-color composite images where band 4 represents red, band 3, green, and band 2, blue. This band combination makes vegetation appear as shades of red, brighter reds indicating more vigorously growing vegetation. Soils with no or sparse vegetation will range from white (sands) to greens or browns depending on moisture and organic matter content. Water bodies will appear blue. Deep, clear water will be dark blue to black in color, while sediment-laden or shallow waters will appear lighter in color. Urban areas will appear blue-gray in color. Clouds and snow will be bright white. They are usually distinguishable from each other by the shadows associated with the clouds.

Spatial Resolution

A Landsat 4 and 5 TM scene has an instantaneous field of view (IFOV) of 30 square meters in bands 1 through 5 and band 7,band 6 has an IFOV of 120 square meters on the ground.

The resolution for the TM sensor is shown below:

Temporal Coverage
Background information and status of Landsat satellites.
Satellite Launched Decommissioned Sensors

Landsat 1 July 23, 1972 January 6, 1978 MSS and RBV
Landsat 2 January 22, 1975 February 25, 1982 MSS and RBV
Landsat 3 March 5, 1978 March 31, 1983 MSS and RBV
Landsat 4 July 16, 1982 * TM and MSS
Landsat 5 March 1, 1984 ** TM and MSS

* in standby mode used for range and command as of December 14, 1993.
** currently operational

Spectral Range

The thematic mapper (TM) is an advanced, multispectral scanning, Earth resources sensor designed to achieve higher image resolution, sharper spectral separation, improved geometric fidelity, and greater radiometric accuracy and resolution than the MSS sensor. TM data are scanned simultaneously in seven spectral bands. Band 6 scans thermal (heat) infrared radiation.

Radiometric range of bands and resolution for the TM sensor (from Landsat 4 Data Users Handbook, 1984, USGS).

Micrometers and their relationship to the electromagnetic spectrum are explained in the glossary.

Data Organization

The Space Imaging EOSAT Fast Format volume set contains a header file, image files, and a trailer file. The first file on each volume, a Read-Me-First file, contains header data. It is in American Standard Code for Information Interchange (ASCII) format and adheres to ANSI and ISO standards. The header file contains a single 1536-byte ASCII record. All alphanumerics are left justified, and all numerics are right justified.

All image files contain only one TM band of image pixels. There are no header records within the image file, nor are there prefix and/or suffix data in the individual image records. Image data may be blocked or unblocked.

The blocking factor is a procedure used to minimize the number of digital tapes required to accommodate a full-scene seven-band image set. Image data are written to tape in individual records and between each record is an inter-record gap (IRG), 0.35 of an inch, separating image file records. Unblocked data contain one line of image data per tape record.

The last volume of the Fast Format image set includes a trailer file. The trailer file contains ephemeris information to compute the approximate spacecraft position for each pixel in the image. This file is in ASCII format and adheres to ANSI and ISO standards.

The structure for a single-volume and a multi-volume set are presented below. Each file is followed by an End-Of-File (EOF) marker. An End-Of-Volume (EOV) marker consists of three EOFs.

[LRSGIS]

Link terkait:

• Path / Row Satelit Landsat untuk wilayah Barat dan Timur Indonesia.