ISODATA is a method of unsupervised classification. Don’t need to know the number of clusters. Algorithm splits and merges clusters. User defines threshold values for parameters. Computer runs algorithm through many iterations until threshold is reached.
1) Cluster centers are randomly placed and pixels are assigned based on the shortest distance to center method
2) The standard deviation within each cluster, and the distance between cluster centers is calculated z Clusters are split if one or more standard deviation is greater than the user-defined threshold z Clusters are merged if the distance between them is less than the user-defined threshold.
3) A second iteration is performed with the new cluster centers
4) Further iterations are performed until: i) the average inter-center distance falls below
the user-defined threshold, ii) the average change in the inter-center distance between iterations is less than a threshold, or iii) the maximum number of iterations is reached