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