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General Workflow
Figure 5.20 General workflow diagram for building footprint extraction through an ENVI supervised (top) and unsupervised (bottom) classification.
Importing Imagery 1) Open ENVI 2) Load the image from the main menu, select File, then Open Image File 3) The Available Band panel will appear, click on the RBG Colour radio button. 4) The bands are entered into the Red, Green and Blue by double-‐clicking on the desired band. 5) Click the Load RGB and observe the image to assure the correct band combination is applied. 6) Now that the image is loaded an unsupervised and supervised classification may be conducted. Unsupervised Classification K-‐Mean Unsupervised Classification The K-‐mean unsupervised classification calculates the initial class mean evenly distributed in the data space and clusters the pixels to the nearest class using a minimum-‐distance technique. The following iterations recalculate the class mean and reclassifies pixels. This process continues until the maximum pixel change threshold or iterations max is reached. All the pixels are classified to the nearest class unless a standard deviation or distance threshold is specified; if the pixels do not meet the criteria than they may remain unclassified. [1] 1) In the ENVI main menu select Classification, Unsupervised, K-‐means. 2) Navigate to the file containing the desired image, press OK.