Feature Identification in Multi-spectral Remotely Sensed Images

Feature identification in aerial photography and other remotely sensed images is primarily aided by the use of multiple spectral bands, from which features on the earth's surface are classified by comparing and contrasting the information found in each band.  Red, green and blue visible electromagnetic radiation (EMR), combined with infrared and near-infrared band layers, all combine to form a multi-spectral snapshot of an area, the radiometric display of which can be manipulated in endless ways.

Some of the ways the multiple spectral bands can be displayed, in order to highlight specific physical features, are depicted in the above graphic.  Three different features are identified by way of their spectral characteristics in each spectral band layer- primarily the pixel brightness in each layer of the multiple bands.  The pixel values (brightness) in each spectral band layer provide a means of feature classification by way of pixel value comparison across the layers.