Cloud Shadow Detection
- Author: J.Spitzm_ller, O.Conrad (c) 2023
- Menu: Imagery | Feature Extraction
Description
This tool derives cloud shadows from detected clouds based on their spectral characteristics as well as terrain, sun position and expected cloud height. The initial cloud mask can be created by the tool "Cloud Detection".
References
- Irish, R.R. (2000): Landsat 7 Automatic Cloud Cover Assessment. In: Shen, S.S., Descour, M.R. [Eds.]: Algorithms for Multispectral, Hyperspectral, and Ultraspectral Imagery VI. Proceedings of SPIE, 4049: 348-355. doi:10.1117/12.410358.
- Tizado, E.J. (2010): GRASS GIS i.landsat.acca. E.J. Tizado's implementation of the ACCA algorithm as proposed by Irish (2000), Irish et al. (2006). Source Code.
Parameters
Name | Type | Identifier | Description | Constraints | |
---|---|---|---|---|---|
Input | Clouds | grid, input | CLOUDS | - | - |
Candidates | grid, input | CAND_GRID_IN | - | - | |
Elevation | grid, input, optional | DEM | - | - | |
Green | grid, input | BAND_GREEN | - | - | |
Red | grid, input | BAND_RED | - | - | |
Near Infrared | grid, input | BAND_NIR | - | - | |
Shortwave Infrared | grid, input | BAND_SWIR | - | - | |
Thermal | grid, input, optional | BAND_THERMAL | - | - | |
Brightness Bands | grid list, input | BANDS_BRIGHTNESS | - | - | |
Output | Cloud Number | grid, output, optional | CLOUD_ID | - | - |
Candidates | grid, output, optional | CAND_GRID_OUT | - | - | |
Shadows | grid, output | SHADOWS | - | - | |
Cloud Info | table, output | CLOUD_INFO | - | - | |
Options | Grid System | grid system | PARAMETERS_GRID_SYSTEM | - | - |
Grid System | grid system | BANDS_SWIR | - | - | |
Grid System | grid system | BANDS_THERMAL | - | - | |
Output | choice | OUTPUT | - | Available Choices: [0] visible shadow [1] full shadow [2] shadow and clouds Default: 2 | |
Value | floating point number | CAND_GRID_VALUE | - | Default: 0.000000 | |
Unit | choice | THERMAL_UNIT | - | Available Choices: [0] Kelvin [1] Celsius Default: 0 | |
Candidates | choice | CANDIDATES | - | Available Choices: [0] all cells of candidates grid that are not no-data [1] all cells of candidates grid with a specified value [2] average brightness threshold [3] Irish [4] Irish modified by Tizado Default: 0 | |
Brightness Threshold | floating point number | BRIGHTNESS | - | Minimum: 0.000000 Maximum: 1.000000 Default: 0.050000 | |
Processing | choice | PROCESSING | - | Available Choices: [0] all clouds at once [1] cloud by cloud Default: 0 | |
Azimuth | floating point number | SUN_AZIMUTH | Direction of sun clockwise from North [degree]. | Minimum: 0.000000 Maximum: 360.000000 Default: -180.000000 | |
Height | floating point number | SUN_HEIGHT | Height of sun above horizon [degree]. | Minimum: 0.000000 Maximum: 90.000000 Default: 45.000000 | |
Cloud Height | value range | CLOUD_HEIGHT | The range of cloud height above ground to be tested. | - |
Command Line
Usage: saga_cmd imagery_tools 21 [-CLOUDS] [-CAND_GRID_IN ] [-DEM ] [-CLOUD_ID ] [-CAND_GRID_OUT ] [-SHADOWS ] [-CLOUD_INFO ] [-BAND_GREEN ] [-BAND_RED ] [-BAND_NIR ] [-BAND_SWIR ] [-BAND_THERMAL ] [-BANDS_BRIGHTNESS ] [-OUTPUT ] [-CAND_GRID_VALUE ] [-THERMAL_UNIT ] [-CANDIDATES ] [-BRIGHTNESS ] [-PROCESSING ] [-SUN_AZIMUTH ] [-SUN_HEIGHT ] [-CLOUD_HEIGHT_MIN ] [-CLOUD_HEIGHT_MAX ] -CLOUDS: Clouds grid, input -CAND_GRID_IN: Candidates grid, input -DEM: Elevation grid, input, optional -CLOUD_ID: Cloud Number grid, output, optional -CAND_GRID_OUT: Candidates grid, output, optional -SHADOWS: Shadows grid, output -CLOUD_INFO: Cloud Info table, output -BAND_GREEN: Green grid, input -BAND_RED: Red grid, input -BAND_NIR: Near Infrared grid, input -BAND_SWIR: Shortwave Infrared grid, input -BAND_THERMAL: Thermal grid, input, optional -BANDS_BRIGHTNESS: Brightness Bands grid list, input -OUTPUT: Output choice Available Choices: [0] visible shadow [1] full shadow [2] shadow and clouds Default: 2 -CAND_GRID_VALUE: Value floating point number Default: 0.000000 -THERMAL_UNIT: Unit choice Available Choices: [0] Kelvin [1] Celsius Default: 0 -CANDIDATES: Candidates choice Available Choices: [0] all cells of candidates grid that are not no-data [1] all cells of candidates grid with a specified value [2] average brightness threshold [3] Irish [4] Irish modified by Tizado Default: 0 -BRIGHTNESS: Brightness Threshold floating point number Minimum: 0.000000 Maximum: 1.000000 Default: 0.050000 -PROCESSING: Processing choice Available Choices: [0] all clouds at once [1] cloud by cloud Default: 0 -SUN_AZIMUTH: Azimuth floating point number Minimum: 0.000000 Maximum: 360.000000 Default: -180.000000 -SUN_HEIGHT: Height floating point number Minimum: 0.000000 Maximum: 90.000000 Default: 45.000000 -CLOUD_HEIGHT_MIN: Cloud Height value range -CLOUD_HEIGHT_MAX: Cloud Height value range