Ground Feature

Bands Used

Contrast Manipulation

Limits

Water

1,2,3; 1,2,4; 1,4,5

No

No

Urban

1,2,3; 1,4,5

Yes band 4 (1,4,5)

Yes band 4 (1,4,5)

Farmland

1,2,3; 1,4,5

Yes band 4 (1,4,5)

Yes band 4 (1,4,5)

Forest

1,2,3; 1,4,5

Yes band 4 (1,4,5)

Yes band 4 (1,4,5)

Salt Scald

1,2,3; 1,4,5

Yes band 4 (1,4,5)

Yes band 4 (1,4,5)

Scrub

1,4,5

Yes band 4 (1,4,5)

Yes band 4 (1,4,5)

Parks/Golf

1,2,3

No

No

Land Cover Type

Spectral Band Combination

Water

Band 1, 4 & 7 / Band 1, 2 & 3

Urban

Band 1,4 & 7

Farmland

Band 1, 2 & 3

Forest

Band 1, 4 & 7

Salt Scald

Band 1, 2 & 3

Remnant Vegetation

Band 1, 4 & 7

Irrigated Vegetation

Band 1, 4 & 7

Terrain Feature

Reflectance Response

Water

Bodies

Generally reflect high in the visible spectrum, however, clearer water has less reflectance than turbid water.  In the Near IR and Mid-IR regions water increasingly absorbs the light making it darker.  This is dependent upon water depth and wavelength.  Increasing amounts of dissolved inorganic materials in water bodies tend to shift the peak of visible reflectance toward the red region from the green region (clearer water) of the spectrum.

Soil

Northern latitudes have black soils and tropical regions have red soils.  Soil reflectance decreases as organic matter increases.  As soil moisture increases, reflectance of soil decreases at all wavelengths.  Texture of soil will cause increased reflectance with decreased particle size, i.e., the bigger particles (rocks, sand, and soils) basically cast a larger shadow.

Vegetation

The spectral reflectance is based on the chlorophyll and water absorption in the leaf.  Needles have a darker response than leaves.  There will be various shades of vegetation based on type, leaf structure, moisture content and health of the plant.

Man-Made Materials

Concrete and asphalt both display spectral curves that generally increase from the visible through the Near IR and Mid-IR regions.  However, as concrete ages, it becomes darker and as asphalt ages it becomes lighter.

Snow and Ice

Old snow may develop a compacted crust and the moisture content increases which make it less reflective in the Near IR and Mid-IR region.  It is possible to compare old and new snow by its Mid-IR reflectance.

R, G, B

Potential Information Content

4,3,2

The standard "false color" composite.  Vegetation appears in shades of red, urban areas are cyan blue, and soils vary from dark to light browns.  Ice, snow and clouds are white or light cyan.  Coniferous trees will appear darker red than hardwoods.  This is a very popular band combination and is useful for vegetation studies, monitoring drainage and soil patterns and various stages of crop growth.  Generally, deep red hues indicate broad leaf and/or healthier vegetation while lighter reds signify grasslands or sparsely vegetated areas.  Densely populated urban areas are shown in light blue.  This TM band combination gives results similar to traditional color infrared aerial photography.

3,2,1

The "natural color" band combination.  Because the visible bands are used in this combination, ground features appear in colors similar to their appearance to the human visual system, healthy vegetation is green, recently cleared fields are very light, unhealthy vegetation is brown and yellow, roads are gray, and shorelines are white.  This band combination provides the most water penetration and superior sediment and bathymetric information.  It is also used for urban studies.  Cleared and sparsely vegetated areas are not as easily detected here as in the 4 5 1 or 4 3 2 combination.  Clouds and snow appear white and are difficult to distinguish.  Also note that vegetation types are not as easily distinguished as the 4 5 1 combination.  The 3 2 1 combination does not distinguish shallow water from soil as well as the 7 5 3 combination does.

7,4,2

This combination provides a "natural-like" rendition, while also penetrating atmospheric particles and smoke.  Healthy vegetation will be a bright green and can saturate in seasons of heavy growth, grasslands will appear green, pink areas represent barren soil, oranges and browns represent sparsely vegetated areas.  Dry vegetation will be orange and water will be blue.  Sands, soils and minerals are highlighted in a multitude of colors.  This band combination provides striking imagery for desert regions.  It is useful for geological, agricultural and wetland studies.  If there were any fires in this image they would appear red.  This combination is used in the fire management applications for post-fire analysis of burned and non burned forested areas.  Urban areas appear in varying shades of magenta.  Grasslands appear as light green.  The light-green spots inside the city indicate grassy land cover - parks, cemeteries, golf courses.  Olive-green to bright-green hues normally indicate forested areas with coniferous forest being darker green than deciduous.

4,5,1

Healthy vegetation appears in shades of reds, browns, oranges and yellows.  Soils may be in greens and browns, urban features are white, cyan and gray, bright blue areas represent recently clearcut areas and reddish areas show new vegetation growth, probably sparse grasslands.  Clear, deep water will be very dark in this combination, if the water is shallow or contains sediments it would appear as shades of lighter blue.  For vegetation studies, the addition of the Mid-IR band increases sensitivity of detecting various stages of plant growth or stress; however care must be taken in interpretation if acquisition closely follows precipitation.  Use of TM 4 and TM 5 shows high reflectance in healthy vegetated areas.  It is helpful to compare flooded areas and red vegetated areas with the corresponding colors in the 3 2 1 combination to assure correct interpretation.  This is not a good band combination for studying cultural features such as roads and runways.

4,5,3

This combination of near-IR (Band 4), mid-IR (Band 5) and red (Band 3) offers added definition of land-water boundaries and highlights subtle details not readily apparent in the visible bands alone.  Inland lakes and streams can be located with greater precision when more infrared bands are used.  With this band combination, vegetation type and condition show as variations of hues (browns, greens and oranges), as well as in tone.  The 4,5,3 combination demonstrates moisture differences and is useful for analysis of soil and vegetation conditions.  Generally, the wetter the soil, the darker it appears, because of the infrared absorption capabilities of water.

7,5,3

This band combination also provides a "natural-like" rendition while also penetrating atmospheric particles, smoke and haze.  Vegetation appears in shades of dark and light green during the growing season, urban features are white, gray, cyan or purple, sands, soils and minerals appear in a variety of colors.  The almost complete absorption of Mid-IR bands in water, ice and snow provides well defined coast lines and highlighted sources of water within the image.  Snow and ice appear as dark blue, water is black or dark blue.  Hot surfaces such as forest fires and volcano calderas saturate the Mid-IR bands and appear in shades of red or yellow.  One particular application for this combination is monitoring forest fires.  During seasons of little vegetation growth the 7 4 2 combination should be substituted.  Flooded areas should look very dark blue or black, compared with the 3 2 1 combination in which shallow flooded regions appear gray and are difficult to distinguish.

5,4,3

Like the 4 5 1 combination, this combination provides the user with a great amount of information and color contrast.  Healthy vegetation is bright green and soils are mauve.  While the 7 4 2 combination includes TM 7, which has the geological information, the 5 4 3 combination uses TM 5 which has the most agricultural information.  This combination is useful for vegetation studies, and is widely used in the areas of timber management and pest infestation.

5,4,1

This will look similar to the 7 4 2 combination in that healthy vegetation will be bright green, except the 5 4 1 combination is better for agricultural studies.

7,5,4

This combination involves no visible bands.  It provides the best atmospheric penetration.  Coast lines and shores are well defined.  It may be used to find textural and moisture characteristics of soils.  Vegetation appears blue.  If the user prefers green vegetation, a 7 4 5 combination should be substituted.  This band combination can be useful for geological studies.

5,3,1

This combination display topographic textures while 7 3 1 may display differences in rock types.