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<< Click to Display Table of Contents >> Basic Module - Flooding Classification Workflow |
  
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<< Click to Display Table of Contents >> Basic Module - Flooding Classification Workflow |
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Purpose
This functionality enables to execute, in a single iteration, the following processing sequence:
–Sample Selection SAR Geometry Data
–De Grandi Multi-temporal Filtering
–Geocoding and Radiometric Calibration
–Conversion DEM to Slope and Aspect
–Flood Classification Refinement
The final purpose of this processing chain is to enable the generation of terrain geocoded sigma nought data.
Technical Note
Specific details of each step are described in their respective reference help page. We recommend to read them carefully.
Note: this workflow allows importing and subsampling SAR data. In case SAR data have already been imported, SARscape recognizes the imported file. In case the SAR data have already been subsampled, these unnecessary step is skipped by setting to True the Skip Sample Selection in the Import Generic SAR Data.
Input
Input Files
Area of Interest
In case of SLC IW import, a vector file (.shp), or a Google Earth file (.kml or .kmz) can be upload to specify a region of interest. Only the bursts intersecting this region will be imported. This will reduce the import processing time and disk space needs. This file is optional.
Note: Only AOI files in geographic coordinates (Lat/Long) are supported. If the needed shapefile is available only in another cartographic system, please use the Cartographic Transformation Shape tool to convert it in Lat/Long.
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.
DEM/Cartographic System
Reference Type
The choice is given between the three following options:
•Input DEM: the provided "Input Digital Elevation Model" file is used in the process;
•Reference Height: in case that the Digital Elevation Model is not used, the parameters needed to define the Cartographic System, the pixel spacing and the reference height are compulsory;
•DEM Download: The Digital Elevation Model Extraction tool is used to download an online digital elevation model. Various sources are available, see this section for further information.
note that the choice of one source is compulsory.
Parameters
Grid Size
The grid size of the output data must be defined; the default unit of measure is meters.
Note that - for the Geographic projection - if values higher than 0.2 are entered they will be considered as metric units and then automatically, and roughly, converted from meters to degrees; if values lower than 0.2 are entered they will be considered as degree and used as such without any conversion.
Filter Method
Choose the Filter method. Note that in order to avoid the generation of artifacts it is important to set the ''apply constrains field to true.
Window Size
Size – in meters – of the moving window.
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 dependent 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.
Skip Refinement Step
Set this field to true to skip the Flooding Classification Refinement Step.
Import SAR Data
It allows importing generic SAR data. Some parameters refer only to Sentinel-1 data , in this case "SENTINEL" is reported in the specific field to fill out. For more details refer to Import Data Generic SAR data.
Sample Selection SAR
It allows subsampling a spatial subset to be extracted from a single image or from an image stack. For more details refer to the sample selection in SAR geometry.
Multilooking
It brings to the principal parameters of the Multilooking step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Coregistration
It brings to the principal parameters of the Coregistration step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
De Grandi Multi-temporal Filtering
It brings to the principal parameters of the De Grandi Multi-temporal Filtering step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Geocoding and Radiometric Calibration
It brings to the principal parameters of the Geocoding and Radiometric Calibration step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Conversion DEM to Slope and Aspect
It brings to the principal parameters of the Conversion DEM to Slope and Aspect step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Flooding Classification
It brings to the principal parameters of the Flood Classification step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Flooding Classification Refinement
It brings to the principal parameters of the Flood Classification Refinement step. Refer to the relevant section technical note for further information about the process and other Preferences parameters.
Output
Output Root Name
Name of the output root. This file is mandatory.
Delete Temporary Files
By setting this flag, temporary files which are created in the intermediate steps, are automatically removed. All of the intermediate files are kept otherwise, refer to the Output lists relevant to each processing step for further information.
flood_geo
Classified raster file of the flooded areas.
floodPreEvent_geo
Mean amplitude image based on the list of pre-event images.
floodRatio_geo
Geocoded ratio (expressed in dB) between the post-event backscatter value and the pre-events backscatter value.
Details specific to the Units of Measure and Nomenclature of the output products can be found in the Data Format section
General Function(s)
Preview
By setting this flag, the temporary files are made available to visualize after a single step in the chain.
Delete Temporary Files
By setting this flag to false, It is possible to keep all the temporary files created during the processing. The files are located in the ENVI Output Directory in a folder with the following name: SARsTmpDir_ddmmmyyyy_hhmmss
Save
Clicking this button allows to save and close the workflow at the actual step. After saving the workflow the window will be closed
Open
Clicking this button allows to open a previously saved workflow.
< Back
Clicking this button the previous step of the workflow is shown.
Next >
Clicking this button the actual step of the workflow is performed. once finished, the next step is shown.
Next >>>
Clicking this button all the steps are performed in succession and it is no more necessary to use the "Next >" button. Make sure that all settings in all the steps are correctly set before starting with this processing.
Close
The window will be closed.
References
Consult the reference guide specific to each processing step.