Tool Name	Cloud Detection
Tool ID	20
Library ID	imagery_tools
Version	1.0
Author(s)	J.Spitzmüller, O.Conrad (c) 2023

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
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