Unsupervised classification (การจําแนกแบบไม่กํากับดูแล) that commonly referred to as
clustering (การแบ่งกลุ่ม) is an effective method of partitioning remote sensor image data in
multispectral feature space and extracting land-cover information.
Compared to supervised classification, unsupervised classification normally requires only a
minimal amount of initial input from the analyst. This is because clustering does not
normally require training data.
Clustering is the process where numerical operations are performed that search for natural
groupings of the spectral properties of pixels, as examined in multispectral feature space.
The clustering process results in a classification map consisting of m spectral classes. The
analyst then attempts a posteriori (after the fact) to assign or transform the spectral classes
into thematic information classes of interest (e.g., forest, agriculture).
The analyst must understand the spectral characteristics of the terrain well enough to be able
to label certain clusters as specific information classes.
Hundreds of clustering algorithms have been developed. Some common clustering which
commonly used in unsupervised classification here are explained include: