Cloud Detection

Author(s)	J.Spitzmüller, O.Conrad (c) 2023
Library ID	imagery_tools
Tool ID	20
Version	1.0
Menu	Imagery \| Feature Extraction

Description

This tool implements pass one of the Function of mask (Fmask) algorithm for cloud and cloud shadow detection in Landsat imagery. Landsat Top of Atmosphere (TOA) reflectance and Brightness Temperature (BT) are used as input. Alternatively you can choose the scene-average automated cloud-cover assessment (ACCA) algorithm as proposed by Irish (2000) and Irish et al. (2006). This tool can optionally pass the cloud mask to the "Cloud Shadow Detection" tool as well.

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

Irish, R.R., Barker, J.L., Goward, S.N., Arvidson, T. (2006): Characterization of the Landsat-7 ETM+ Automated Cloud-Cover Assessment (ACCA) Algorithm. Photogrammetric Engineering and Remote Sensing vol. 72(10): 1179-1188. doi:10.14358/PERS.72.10.1179

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

Zhu, Z., Wang, S., Woodcock, C.E. (2015): Improvement and expansion of the Fmask algorithm: cloud, cloud shadow, and snow detection for Landsats 4-7, 8, and Sentinel 2 images. Remote Sensing of Environment 159, 269-277. doi:10.1016/j.rse.2014.12.014

Zhu, Z., Woodcock, C.E. (2012): Object-based cloud and cloud shadow detection in Landsat imagery. Remote Sensing of Environment 118, 83-94. doi:10.1016/j.rse.2011.10.028

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Blue	grid, input	`BAND_BLUE`	-	-
	Green	grid, input	`BAND_GREEN`	-	-
	Red	grid, input	`BAND_RED`	-	-
	Near Infrared	grid, input	`BAND_NIR`	-	-
	Shortwave Infrared 1	grid, input	`BAND_SWIR1`	-	-
	Shortwave Infrared 2	grid, input	`BAND_SWIR2`	-	-
	Thermal	grid, input, optional	`BAND_THERMAL`	-	-
	Cirrus	grid, input, optional	`BAND_CIRRUS`	-	-
Output	Clouds	grid, output	`CLOUDS`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Grid System	grid system	`BANDS_SWIR`	-	-
	Grid System	grid system	`BANDS_THERMAL`	-	-
	Grid System	grid system	`BANDS_CIRRUS`	-	-
	Unit	choice	`THERMAL_UNIT`	-	Available Choices: [0] Kelvin [1] Celsius Default: 0
	Algorithm	choice	`ALGORITHM`	-	Available Choices: [0] Fmask [1] ACCA Default: 0
	SWIR/Thermal Threshold	floating point number	`ACCA_B56C`	Threshold for SWIR/Thermal Composite (step 6).	Default: 225.000000
	Desert Detection Threshold	floating point number	`ACCA_B45R`	Threshold for desert detection (step 10, NIR/SWIR Ratio).	Default: 1.000000
	Temperature Histogram	integer number	`ACCA_HIST_N`	Number of classes in the cloud temperature histogram.	Minimum: 10 Default: 100
	Cloud Signature	boolean	`ACCA_CSIG`	Always use cloud signature (step 14).	Default: 1
	Cloud Differentiation	boolean	`ACCA_PASS2`	Differentiate between warm (not ambiguous) and cold clouds.	Default: 0
	Shadows	boolean	`ACCA_SHADOW`	Include a category for cloud shadows.	Default: 0
	Shadow Detection	boolean	`SHADOWS`	Run cloud shadow detection tool with standard settings.	Default: 0
	Sun's Azimuth	floating point number	`SUN_AZIMUTH`	Direction of sun clockwise from North [degree].	Minimum: 0.000000 Maximum: 360.000000 Default: -180.000000
	Sun's Height	floating point number	`SUN_HEIGHT`	Height of sun above horizon [degree].	Minimum: 0.000000 Maximum: 90.000000 Default: 45.000000

Command Line


Usage: saga_cmd imagery_tools 20 [-CLOUDS ] [-BAND_BLUE ] [-BAND_GREEN ] [-BAND_RED ] [-BAND_NIR ] [-BAND_SWIR1 ] [-BAND_SWIR2 ] [-BAND_THERMAL ] [-BAND_CIRRUS ] [-THERMAL_UNIT ] [-ALGORITHM ] [-ACCA_B56C ] [-ACCA_B45R ] [-ACCA_HIST_N ] [-ACCA_CSIG ] [-ACCA_PASS2 ] [-ACCA_SHADOW ] [-SHADOWS ] [-SUN_AZIMUTH ] [-SUN_HEIGHT ]
  -CLOUDS:           Clouds
	grid, output
  -BAND_BLUE:        Blue
	grid, input
  -BAND_GREEN:       Green
	grid, input
  -BAND_RED:         Red
	grid, input
  -BAND_NIR:         Near Infrared
	grid, input
  -BAND_SWIR1:       Shortwave Infrared 1
	grid, input
  -BAND_SWIR2:       Shortwave Infrared 2
	grid, input
  -BAND_THERMAL:     Thermal
	grid, input, optional
  -BAND_CIRRUS:      Cirrus
	grid, input, optional
  -THERMAL_UNIT:     Unit
	choice
	Available Choices:
	[0] Kelvin
	[1] Celsius
	Default: 0
  -ALGORITHM:        Algorithm
	choice
	Available Choices:
	[0] Fmask
	[1] ACCA
	Default: 0
  -ACCA_B56C:     SWIR/Thermal Threshold
	floating point number
	Default: 225.000000
  -ACCA_B45R:     Desert Detection Threshold
	floating point number
	Default: 1.000000
  -ACCA_HIST_N:      Temperature Histogram
	integer number
	Minimum: 10
	Default: 100
  -ACCA_CSIG:        Cloud Signature
	boolean
	Default: 1
  -ACCA_PASS2:       Cloud Differentiation
	boolean
	Default: 0
  -ACCA_SHADOW:      Shadows
	boolean
	Default: 0
  -SHADOWS:          Shadow Detection
	boolean
	Default: 0
  -SUN_AZIMUTH:
                          Sun's Azimuth
                          	floating point number
                          	Minimum: 0.000000
                          	Maximum: 360.000000
                          	Default: -180.000000
  -SUN_HEIGHT:    Sun's Height
	floating point number
	Minimum: 0.000000
	Maximum: 90.000000
	Default: 45.000000