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Natural Resources Canada > Earth Sciences Sector > Priorities > Canada Centre for Remote Sensing
Tour Canada from space Gaspé Peninsula, Québec
 This Landsat TM image presents the Gaspé peninsula, an area of Quebec well known for the beauty of its scenery, the ocean, the warmth of its people and the wealth of its natural resources. The scenery here, is from a vertical vantage point, very suitable for interpreting the landcover, landuse, geology, hydrology, settlement patterns and forestry of the region.People have traditionally settled the coastal zone of new territories, taking advantage of transportation via the sea. The incised pattern of river valleys, geological faults and dense forests of the interior were a further encouragement for coastal settlements. Thus, that is where agriculture first started and remains to this day. Tourists also enjoy the coastal areas for their unusual offshore features, coastal scenery such as river mouth deltas, and the many small towns and villages. The interior of the peninsula shows much forest cutting activity. Satellite remote sensing is an efficient way to monitor various forest dynamics such as clear-cutting, logging road construction, forest regeneration and sylviculture and various forms of damage due to pests, disease, fires and wind. To the trained eye of the remote sensing geologist, the forest cover does not fully hide the history of earth movement, soil and rock types and surface and subsurface features. The patterns evident in the imagery have much to tell about the dynamic processes that have taken place!
Question: If the Landsat TM has seven bands, why are only three shown in colour composites like this one? [ Answer ]
About this Image
| Location: |
Gaspé Peninsula, Quebec |
| NTS map(s): |
22 A/H |
 Location Map: |
See a detailed map (1:1M) of the region |
| Image Date: |
August 26, 1993 |
| Satellites/Sensors: |
Landsat TM |
| Resolution: |
170 m pixels |
| Image Area: |
108 x 132 km |
| Image Features: |
Town, vegetation, delta, river, sediment, water depth, farm, field, settlement, cloud, shadow, slope, bank, fractures, roads, railroad, bare soil, crops, pasture, forest, Percé, causeway, rock, island, sediments, sand bar, lagoon, coastal marsh, longhsore drift, clearcuts, regeneration, logging roads, faults, linears, rock control, folding, sandstone, mudstone, basalt, texture, stratification |
| Related Tour Images: |
Winnipeg, Manitoba; Whiteshell Park, Manitoba; Liard River Valley, Yukon |
| Related Glossary Terms: |
These terms from the CCRS Glossary may help you to understand this image and its interpretation:
image texture, tone, brightness, contrast, contrast enhancement, contrast stretch, additive colour, false colour composite, true colour, plant reflectance |
| 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:
2.8 4.2 5.5 5.7.2
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| Image Credits: |
Image interpretation by: Tom Alföldi, Robert Saint-Jean, Terry Pultz, Heather McNairn |
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Additional
Information: | The original TM image was acquired by the Landsat 5 satellite on August 26, 1993 at 14:28:44 UTC. The data was transmitted to, and recorded by the CCRS Gatineau Satellite Station. An image segment of 3613 x 4405 pixels, at the full resolution of 30m, was decimated to 636 x 775 pixels, resulting in the new pixel spacing of approximately 170 metres. |
| Question: |
If the Landsat TM has seven bands, why are only three shown in colour composites like this one? |
| Answer: |
The limitation to three bands is not due to the sensor but to the human vision system. With the three additive primary colours of red, green and blue, we can produce all the colours that the human eye can see and the brain interpret. That is why television sets and computer monitors, for instance, have R, G, B input. It is quite common, therefore, to feed a different TM band to each of these three primaries. The mix of the bands produce the intermediate colours that we see. If we were able to show more TM bands at the same time, there would be more information, but our human limitations are a barrier. There are many schemes for transforming, combining, compositing information from more than three bands and displaying them in the three channels of red, green and blue. But each of these is some form of compromise. |
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