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I have been trying to roughly polygonize vegetation areas from Imagery (RGB). I tried using Iso Cluster Unsupervised Classification (Spatial Analyst) but it is still too detailed for my purpose. I just need to roughly draw polygons wherever I have dense vegetation as can be seen here:enter image description here

Any idea/ thought to put me on the right track is much appreciated.

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1 Answer 1

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Vegetation extraction is a bit more complex than running the spatial analysis tools that you named. For better results I would suggest the following:

  • run analysis on a 4 band image (e.g. R,G,B,NIR)
  • change image to be symbolized as 432 for RGB not 321
  • create training samples that represent vegetation and run a supervised classification

These steps will give you a fair result, however you will still get many false returns (e.g. shadows by buildings, or green water bodies...etc).

For best results you will have to use a remote sensing software (including the three bullets above) that analyzes both spectral and textual objects of the imagery. I asked a question about what free software exists that can do this type of analysis, see link below:

Land Cover Feature Extraction from Satellite Imagery

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Say you wanted to digitize buildings in a similar way? Any thoughts on how to do that? –  GISKid Nov 1 '13 at 19:34
    
@GISKid, yes same idea but different training set. –  artwork21 Nov 1 '13 at 19:59

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