The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
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Village roads: The extraction of the village roads is similar to the extraction of the 
roads for transporting. However, they need be distinguished due to they have similar 
image characteristics. It is difficult to separate them only using RS images. In practice, 
it is necessary to rely on original information (such as traffic maps) to manual 
distinction. According to the characteristics of Tibetan Plateau, the suggestion is to 
change the scheme to express them as the passable section. 
Rivers, lakes and reservoirs: They mainly depend on colour, shape and size to 
recognize. On the pseudo-colour image (synthesis of multispectral 4, 3, 2 bands), the 
water is bright blue and could be easily distinguished from the surrounding ground 
objects. Besides, the border of lakes and the riverway of rivers are clear, therefore they 
can be easily identified. 
Springs: The Springs identification mainly depends on their position, shape, colour 
and size. They are mostly located at the end of river branches with irregular polygon. 
They are smaller than lakes, and have similar colour with water. 
Swamps: The swamps extraction mainly based on their position and colour to judge. 
Swamps usually located at the edge of lakes. They have both spectral characteristics of 
water and soil. However, due to they are not uniform mixing and water covers the 
swamps surface, the spectral characteristics are not shown as a unique spectrum from 
the arithmetic superposition of two spectral information. It is represented as two 
spectrums appear alternately in space and the water spectrum appears with a higher 
frequency. 
Dry riverbeds, dry lakes: The rivers and lakes without water are classified as this 
type due to only single-temporal image was available. If multi-temporal images are 
available, the seasonal rivers and lakes could be distinguished. Dry riverbeds and lakes 
have the similar shape with swamps in images and they always intersect with swamps. 
In addition, their colour and texture are similar to gravel because they don’t have 
water.