Multi Direction Lee Filter

Author(s)	A.Ringeler (c) 2003
Library ID	grid_filter
Tool ID	3
Version	1.0
Menu	Grid \| Filter

Description

The tool searches for the minimum variance within 16 directions and applies a Lee Filter in the direction of minimum variance. The filter is edge-preserving and can be used to remove speckle noise from SAR images or to smooth DTMs. Applied to DTMs, this filter will preserve slope breaks and narrow valleys. For more details, please refer to the references.

References

Lee, J.S. (1980): Digital image enhancement and noise filtering by use of local statistics. IEEE Transactions on Pattern Analysis and Machine Intelligence, PAMI-2: 165-168.

Lee, J.S., Papathanassiou, K.P., Ainsworth, T.L., Grunes, M.R., Reigber, A. (1998): A New Technique for Noise Filtering of SAR Interferometric Phase Images. IEEE Transactions on Geosciences and Remote Sensing 36(5): 1456-1465.

Selige, T., BÃ¶hner, J., Ringeler, A. (2006): Processing of SRTM X-SAR Data to correct interferometric elevation models for land surface process applications. In: BÃ¶hner, J., McCloy, K.R., Strobl, J. [Eds.]: SAGA - Analysis and Modelling Applications. GÃ¶ttinger Geographische Abhandlungen, Vol. 115: 97-104. http://downloads.sourceforge.net/saga-gis/gga115_09.pdf

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Grid	grid, input	`INPUT`	-	-
Output	Filtered Grid	grid, output	`RESULT`	-	-
	Minimum Standard Deviation	grid, output, optional	`STDDEV`	-	-
	Direction of Minimum Standard Deviation	grid, output, optional	`DIR`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Estimated Noise (absolute)	floating point number	`NOISE_ABS`	Estimated noise in units of input data	Minimum: 0.000000 Default: 1.000000
	Estimated Noise (relative)	floating point number	`NOISE_REL`	Estimated noise relative to mean standard deviation	Minimum: 0.000000 Default: 1.000000
	Weighted	boolean	`WEIGHTED`	-	Default: 1
	Method	choice	`METHOD`	-	Available Choices: [0] noise variance given as absolute value [1] noise variance given relative to mean standard deviation [2] original calculation (Ringeler) Default: 1

Command Line


Usage: saga_cmd grid_filter 3 [-INPUT ] [-RESULT ] [-STDDEV ] [-DIR ] [-NOISE_ABS ] [-NOISE_REL ] [-WEIGHTED ] [-METHOD ]
  -INPUT:          Grid
	grid, input
  -RESULT:         Filtered Grid
	grid, output
  -STDDEV:         Minimum Standard Deviation
	grid, output, optional
  -DIR:            Direction of Minimum Standard Deviation
	grid, output, optional
  -NOISE_ABS:   Estimated Noise (absolute)
	floating point number
	Minimum: 0.000000
	Default: 1.000000
  -NOISE_REL:   Estimated Noise (relative)
	floating point number
	Minimum: 0.000000
	Default: 1.000000
  -WEIGHTED:       Weighted
	boolean
	Default: 1
  -METHOD:
                        Method
                        	choice
                        	Available Choices:
                        	[0] noise variance given as absolute value
                        	[1] noise variance given relative to mean standard deviation
                        	[2] original calculation (Ringeler)
                        	Default: 1