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Cartographie et données satellite
 
A model with a grid
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A simple example of traditional chorological mapping methods can show some of the fundamental principles of satellite images. In each square, the number of houses is counted as the basis of the chorological matrix.

Credits: ESA
 
  Matrice chorologique
 
Chorological matrix
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Chorological matrix.

Credits: ESA
 
  Histogramme
 
Two classification examples based on a histogram
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The illustration shows two classification examples based on the histogram shown. One classification has four classes (agriculture, village, town, and other) whereas the other has two (rural and town).

Credits: ESA
 
  Classification
 
Suitable classification depends on the purpose of the map
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Suitable classification depends on the purpose of the map.

Credits: ESA
 
 
Classifications often require compromise
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Classification often requires compromise.

Credits: ESA
 
 
A digital image is a chorological matrix
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A digital image is a chorological matrix. The size of the squares in the grid is equal to the spatial resolution of the (satellite) image and depend upon the instrument providing the data. Similarly the numbers in the grid are determined by the ability of the equipment to distinguish variations. Digital images often contain values between 0 and 255, which are matched exactly by the capacity of 1 byte in the computer.

Credits: ESA
 


 
 
 
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