In general, there are 3 remote sensing techniques, which are ground-based, airborne and space borne techniques.

íP Radar intensity images
Contains intensity values correlating to the backscattering coefficient of the EarthíŽs surfaces

íP Intensity difference images
Calculate the offset intensity image values

íP Coherence images
Measure the similarity correlation between the pixels



Data processing

University of New South Wales

Integrated Remote Sensing For Flood Mapping

Fundamental information

There are some basic steps to follow in ArcGIS in order to generate flood mapsíX Intensity images and coherence images.

On the other hand, intensity differences can be calculated and created as well. After importing the images into ArcGIS, we use raster calculator to subtract between the pixel values. The new image then can be demonstrated by stretched colours. Then we add the basemap to form a flood intensity analysis.

For some noisy data, more steps are required to map out the flood. After importing the images, we can use a low pass filter to smooth out the pixels value. If the images still contain large amount of noises, then we can convert the images into polygons after reclassifying the pixel values. The excess polygons which are not representing the flood extents will be deleted.

The steps start from importing the images, we try to familarise it, identify different feature'síŽ pixels, determine and set the threshold values, select blue colour as flood extent, and either add the basemap or export to Google Earth.