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Exercise 3981. Points 2, theme: Creating a Point Pattern

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Generate 100 random locations to the forests of map sheet 54443 (pixel values 64 and 67 in the attached file PK54443.rst) and present the result with map or ortophoto background. If the map covers a larger area then the sheet boundary should be visible.


  • Open the SDC and find Random points.
  • Select Simple random and input 100 as the total number of child points.
  • Open the attached archive and unpack the rst mask file.
  • The number of rows and columns is in the rdc file. You can also find boundary coordinates in the Lambert-Est system in the rdc file.
  • Land cover forest has pixel value 64 and category young forest 67. There are no categories between these values. So, the included area is defined by the interval 64...67. The mask layer must be reclassified in more complicated cases, using e.g. RECLASS in Idrisi.
  • Select Background: ortophoto or map to get image, where both the distribution of points and forests is visible.
  • Select the the mask file for upload and press the button Calculate
  • A quick but primitive image can be saved by mouse right-click and selecting Copy image, or by using print screen from the keyboard. For a better designed drawing, copy the coordinates from result panel and use advanced GIS software.
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