Change Detection Remote Sensing, GIS and Change Detection 1. Remote Sensing

12 2.2. Remote Sensing, GIS and Change Detection 2.2.1. Remote Sensing Remote sensing is the science and art of obtaining information about an object, area, or phenomenon through the analysis of data acquired by a device that have no any contact with the object, area, or phenomenon investigated Lillesand and Kiefer 2000. Remote sensing is the instrumentation, techniques and methods to observe the Earth’s surface at a distance and to interpret the images or numerical values obtained in order to acquired meaningful information of particular object on Earth Buiten and Clevers 1993. Before the image data can produce the required the information about the objects or phenomenon of interest, they need to be processed. The analysis and information extraction or information production is a part or overall remote sensing process, known as image processing. Digital image processing involves the manipulation and interpretation of digital image with the aid of a computer and a certain program or software. The central idea image behind digital image processing is quite simple. The digital image is fed into computer one pixel at a time. The computer is programmed to insert these data into an equation, or series of questions, and then store the results of the computation for each pixel. These results form a new digital image that may be displayed or recorded in pictorial format may itself be further manipulated by additional programs Lillesand and Kiefer 2000.

2.2.2. Change Detection

Change detection is the process of identifying differences in the state of an object or phenomenon by observing it in different times. The basic premise in using remote sensing data for change detection is that changes in the object of interest will result in changes 13 in radiance values or local texture that are separable from changes caused by other factors, such as differences in atmospheric conditions, illumination and viewing angle, soil moisture, etc. It may further be necessary to require that changes of interest be separable from expected or uninteresting events, such as seasonal, weather, tidal or diurnal effects. Some techniques also assume that the areas of change will be relatively small Deer 2004.

2.2.3. Geographical Information System