i.sentinel_1.change - GRASS manual

NAME

i.sentinel_1.change - Extracts changes from Sentinel-1 Scenes from two dates.

KEYWORDS

SYNOPSIS

i.sentinel_1.change

i.sentinel_1.change --help

i.sentinel_1.change date1_vv=name date1_vh=name date2_vv=name date2_vh=name [change_threshold=float] [min_size=float] output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

date1_vv=name [required]: Input raster map of first date in VV polarization (dB); Name of input raster map
date1_vh=name [required]: Input raster map of first date in VH polarization (dB); Name of input raster map
date2_vv=name [required]: Input raster map of second date in VV polarization (dB); Name of input raster map
date2_vh=name [required]: Input raster map of second date in VH polarization (dB); Name of input raster map
change_threshold=float: Minimum change in ratio (date2/date1) map to be considered (all areas with values from (1-<change_threshold>) to (1+<change_threshold>) will be considered unchanged); Options: 0.0-1.0; Default: 0.75
min_size=float: Minimum size of identified changed areas in ha; Default: 1.0
output=name [required]: Output raster map containing areas of change; Name for output raster map

DESCRIPTION
EXAMPLE
SEE ALSO
AUTHOR

DESCRIPTION

i.sentinel_1.change is a GRASS GIS addon that extracts areas of changed backscatter values from two Sentinel-1 input scenes. The input backscatter values are expected in dB scale. The addon calculates two polarisation ratios (date2_vv/date1_vv and date2_vh/date1_vh), smoothes them with a median filter in r.neighbors and applies the user-defined thresholds 1+change_threshold and 1-change_threshold to identify areas of change. For example, a change_threshold of 0.5 would mean that areas with a ratio <= 0.5 are identified as signal decrease, and areas with a ratio of >= 1.5 are identified as signal increase.

EXAMPLE

i.sentinel_1.change date1_vv=Date1_Sigma0_VV_log date1_vh=Date1_Sigma0_VH_log date2_vv=Date2_Sigma0_VV_log date2_vh=Date2_Sigma0_VH_log output=changed_areas change_threshold=0.75 min_size=1.0 --o

AUTHOR

Guido Riembauer, mundialis, Germany

SOURCE CODE

Available at: i.sentinel_1.change source code (history)

Accessed: Monday Jul 27 12:22:39 2026