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Natural Resources Canada > Earth Sciences Sector > Priorities > Canada Centre for Remote Sensing
Tour Canada from space Lake Laberge, Yukon
 Lake Laberge was made famous by Robert Service in a poetic way, but we can show you the poetry of science, as colours, shapes, tones, and textures lead us in observing and interpreting the natural and man-made features of the Earth's surface.
Whitehorse, (northern part, southern part) the Yukon's capital, sits among several mountains and alongside the Yukon River. It was threatened in 1998 by a large forest fire whose scar is very visible in this image a year later. What else can we see? Lots! Just look carefully, and analyze.
Question: If the Landsat 7 ETM band 4 is infrared (which wavelengths are invisible to the human eye), why can we see it on this image?
[ Answer ]
About this Image
| Location: |
Lake Laberge, Yukon |
| NTS map(s): |
105 D, E |
 Location Map: |
See a detailed map (1:1M) of the region |
| Image Date: |
August 1, 1999 |
| Satellites/Sensors: |
Landsat 7 ETM
RGB = bands 4, 3, 2 |
| Resolution: |
156 m pixels |
| Image Area: |
3381 x 0.030 = 101.5 km
4082 x 0.030 = 122.5 km |
| Image Features: |
Burn scar, forest fire, slope, spatial resolution, interpretation, sediment, mountain, trees, bushes, grass, soil, landslide, vegetation, forest fire, aspect, reflection, bare ground, pavement, street grid, street pattern, downtown, neighbourhoods, resolution, tank farm, airphoto, vegetation, airport, gravel pit, mine, airstrip, lakes, overburden, glaciation, golf course, fairways, shape, colour, texture, tone, utility lines, bridges, river, city, fields, man-made features, swamp, shorelines, bare rock, river valley, burnt forest, creek, road, islands, airphoto, exposed bedrock, sediment plume, lake, flyover. |
| Related Tour Images: |
The Liard River Valley, Yukon; Norman Wells, NWT; Trepassey, Newfoundland; Whiteshell Provincial Park, Manitoba. |
| Related Glossary Terms: |
These terms from the CCRS Glossary may help you to understand this image and its interpretation:
additive colour, brightness, false colour, image texture, multispectral scanner, tone |
| Related Tutorial Sections: |
These sections of the "Fundamentals of Remote Sensing" tutorial by CCRS will help you to better understand this image and its interpretation:
1.5 1.7 2.8 2.12 4.2 4.5 5.3 5.7
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| Image Credits: |
Satellite image reception, enhancement and interpretation by the Canada Centre for Remote Sensing
Airphotos and topographic maps are copyrighted by, and provided courtesy of the Centre for Topographic Information, Natural Resources Canada
Image pre-processing by RADARSAT International Inc. |
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Additional
Information: | Lake Laberge is a widened portion of the Yukon River which flows through the lake. The lake is 628 m above sea level, has a surface area of 201 sq km. and a mean depth of 54 m. It is an oligotropic lake, deep, and is thus quite dark, as evidenced in the satellite image. NAPL Airphoto series used for this scene:
A28116: 1994.08.03
A28117: 1994.08.02
A27175: 1987.08.23
A27174: 1987.08
Original satellite image segment: 3381 x 4082 pixels.
Laberge overview: 650 x 784 pixels.
Decimation factor: 5.202.
Resolution of overview: 30 x 5.202 = 156 m. |
| Question: |
If the Landsat 7 ETM band 4 is infrared (which wavelengths are invisible to the human eye), why can we see it on this image? |
| Answer: |
The reflected light from the terrain that reaches the sensor may be in various visible and invisible bands of the spectrum. On a colour composite image, such as the one shown here, that light is coded to appear in the three primary (additive) colours that we can see: red, green and blue. For instance this image represents the bands ETM 4, 3, 2. Band 4 is originally sensitive to a part of the infrared wavelength range, and is shown as red. Band 3 is sensitive to the red part of the spectrum but is shown as green. Band 2 is sensitive to the green part of the spectrum and is shown as blue. Simple - right? |
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