<< Click to Display Table of Contents >> Navigation:  Help Content > Basic Module > Flooding > Flooding Classification

Purpose

This tool creates a classification raster that highlights flooded and permanent water areas.

Technical Note

Here below the requirements regarding the input images:

•The images must be coregistered since the analysis is performed pixel by pixel

•The images must be geocoded.

 

Notes:

•The usage of a DEM and Slope files will increase the accuracy of the result.

•To increase the accuracy of the result it is suggested using multiple pre-event images.
 

Input Files

 

Post Event File

Input file name of the coregistered and geocoded post-event image. This file is mandatory.

 

Pre Event File List

Input file name of the coregistered and geocoded pre-event images. At least one image is required.

 

Optional Files

 

DEM Files

Digital Elevation Model file name. This should be referred to the ellipsoid. In case a list of input files is entered, the DEM must cover the whole imaged area.

 

Slope File

Slope file name.

 

Principal Parameters

 

Water Threshold (dB)

This is the minimum dB value that will be used to detect the presence of water, all the pixels under this value will be considered.

In case of stable water area between the pre-event image and the post event image, the area will be classified as Persistent Water Area.

This parameter is band dependent and it is automatically set from the Flooding Menu inside Preferences Common.

 

DEM Threshold (m)

This is the minimum m value that will be used to remove the presence of Stable Water or Flood, all the pixels over this value will be considered.

 

Slope Threshold (deg)

This is the minimum deg value that will be used to remove the presence of Stable Water or Flood, all the pixels over this value will be considered.

 

Ratio Threshold

This is the minimum ratio value between pre-event and post-event image, that will be used to detect the presence of a flooded area. All the pixels over this value will be considered.

In case of the presence of water in the area and a sufficient ratio value, the area will be classified as Flooded Area.

This parameter is band dependant and it is automatically set from the Flooding Menu inside Preferences Common.

 

High Scattering Point (dB)

This is the backscatter value expressed in decibels relevant to high reflectivity targets, such as ships. This parameter helps avoiding the identification of false positive.

 

Note: The side lobes effect may cause the identification of false positive areas surrounding high reflectivity targets.

 

Parameters - Global

 

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

 

Output Files

 

_class

 

Classified raster file of the flooded areas.

 

_postEvent

 

Mean amplitude image of the post-event image.

 

_preEvent

 

Mean amplitude image based on the list of pre-event images.

 

_ratio

 

Geocoded ratio (expressed in dB) between the post-event backscatter value and the pre-events backscatter value.

 

See Also

 

Task, SARscapeBatch object, SARscapeBatch script example

 

References

 

Amitava Dutta (2009 ): ''Fuzzy c-Means Classification of Multispectral Data Incorporating Spatial Contextual Information by using Markov Random Field''.

Zhi-taoWang (2014): "A Fault Diagnosis Approach for Gas Turbine Exhaust Gas Temperature Based on Fuzzy C-Means Clustering and Support Vector Machine".