[GIS] Identifying training sites

classificationimagery

Prior to image classification, collection of training sites and obtaining a signature file is the most critical step. Field visits with a reliable GPS Unit is usually the first step followed by overlaying the points on the to-be-classified image. Other than this when identifying training sites on satellite images, especially the coarse resolution ones what are the rules normally followed by professionals – like minimum number of pixels in a training site, distance between two training sites for same/different classes, how improvements are made after preliminary classification etc. Standard references are also welcome.

Best Answer

I wont be able to give a great deal of information on this, but there are certain rules I think we need to follow for training sites:

  • Training sites should be spread all over the image i.e. should be covering a large area and not just focussed in a region
  • Just as Georeferencing, training sites should be identified at the corners and at points which give maximum sampling options
  • The objective is to identify a set of pixels that accurately represents spectral variation present within each information region
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