What is remote sensing TM? What is ETM+?

Meaning: TM is the abbreviation of Thematic mapper, which means "thematic plotter" and is an imager carried by LANDSAT satellite in the United States.

Features: high spatial resolution and spectral resolution, extremely rich information and high positioning accuracy.

Band and function:

1 and TM 1 are 0.45 ~ 0.52 microns, which are blue bands, located in the part with the smallest attenuation coefficient of water, and have the greatest penetration to water. It is used to judge the water depth, study the underwater topography and turbidity of shallow water, and draw the map of water system and shallow water.

2. The wavelength of 2.TM2 is 0.52 ~ 0.60 micron, which is a green band and located near the reflection peak of green plants. It is sensitive to the reflection of healthy and lush plants, can identify plant species and evaluate plant productivity, has a certain penetration to water bodies, and can reflect the characteristics of underwater topography, sandbars and coastal sandbars.

3.TM3 is 0.63 ~ 0.69 μ m, which belongs to the red band and is located in the main absorption band of chlorophyll. It can be used to distinguish plant type, coverage and judge plant growth. In addition, this band can also provide abundant plant information for the characteristics of bare surface, vegetation, lithology, stratum, structure, landform, hydrology and so on.

4.TM4 is 0.76 ~ 0.90μ m, which belongs to near infrared band. This band is located in the high reflection area of plants, which reflects a lot of plant information and is mostly used for plant identification and classification. At the same time, it is also located in the strong absorption area of water, which is used to draw the boundary of water and identify geological structures and landforms related to water.

5.TM5 is 1.55 ~ 1.75 μ m, which is located between two water absorption zones in short-wave infrared band, and is sensitive to the water content of plants and soil, thus improving the resolution of crops, with a large amount of information and high application rate. ?

6.TM6 is 10.40 ~ 12.50 micron, which belongs to thermal infrared band, and this band is sensitive to thermal radiation of ground objects.

7.TM7 is 2.08 ~ 2.35 microns, belonging to the mid-infrared band, specially added for geological survey;

Second, ETM+

Meaning: ETM+ (enhanced thematic mapper) is an enhanced thematic mapper.

Features: Enhanced Thematic Imager (ETM+) performs absolute calibration on satellites, improves the resolution and positioning quality of earth observation, adjusts the precision, range and sensitivity of radiation measurement, and reduces the high brightness saturation effect caused by strong reflectors through gain.

The panchromatic band with resolution of 15m is added, and the spatial resolution of thermal infrared channel is doubled to 60m. The coverage area of each scene is 185km* 170km, and the overlapping rate: the horizontal overlapping rate of two adjacent scenes on the equator is 7.3%, and the trajectory overlapping rate is 5%. Band6 has high and low gains respectively.

Band is a function:

The waveband is 1, the wavelength range (micron) is 0.450 ~ 0.5 15, and the ground resolution is 30m.

Band 2, wavelength range (micron) 0.525 ~ 0.605, ground resolution/meter 30m.

Band 3, wavelength range (micron) 0.630 ~ 0.690, ground resolution/meter 30m.

Band 4, wavelength range (micron) 0.775 ~ 0.900, ground resolution/meter 30m.

Band 5, wavelength range (micron) 1.550 ~ 1.750, ground resolution/meter 30m.

Band 6, wavelength range (micron) 10.40 ~ 12.50, ground resolution/meter 60m.

Band 7, wavelength range (micron) 2.090 ~ 2.350, ground resolution/meter 30m.

Band 8, wavelength range (micron) 0.520 ~ 0.900, ground resolution/m15m.

Extended data:

TM image features:

Under the combination of 4, 3 and 2 (RGB) bands, the characteristics of various ground cover types are as follows:

1, forest-forest presents a series of changeable colors such as brown, red and brown. At high altitude, mature coniferous forests are thick brown or dark red; In the middle and low altitude areas, the colors of forests range from brown to red to dark green, and some deciduous forests are rust yellow in winter;

2. Shrubs and grasslands-Compared with neighboring forests, shrubs and grasslands are bright red to light red. At high altitude, a large area of grassland may be reddish or rust red in summer and blue-green in winter;

3. Lakes and rivers-Lakes are usually black patches with clear boundaries, while rivers are black or dark blue. In winter, when water freezes or is covered with snow, it shows different shades of purple;

4. Towns-obvious bright gray or blue gray patches, usually with regular gray lines (highways) passing through;

5. Farmland-patches of green, gray, lavender and light red with varied colors are usually irregularly distributed on both sides of the river valley, but widely distributed in the plain area. Paddy fields along the river are usually blue-gray with water.

Baidu encyclopedia -TM pictures

Baidu encyclopedia -TM (TM picture)

Baidu encyclopedia -ETM

Baidu Encyclopedia-Landsat