org.opencv.calib3d

Class StereoSGBM

java.lang.Object

org.opencv.calib3d.StereoSGBM

public class StereoSGBM
extends Object

Class for computing stereo correspondence using the semi-global block matching algorithm.

class StereoSGBM

// C++ code:

StereoSGBM();

StereoSGBM(int minDisparity, int numDisparities, int SADWindowSize,

int P1=0, int P2=0, int disp12MaxDiff=0,

int preFilterCap=0, int uniquenessRatio=0,

int speckleWindowSize=0, int speckleRange=0,

bool fullDP=false);

virtual ~StereoSGBM();

virtual void operator()(InputArray left, InputArray right, OutputArray disp);

int minDisparity;

int numberOfDisparities;

int SADWindowSize;

int preFilterCap;

int uniquenessRatio;

int P1, P2;

int speckleWindowSize;

int speckleRange;

int disp12MaxDiff;

bool fullDP;...

};

The class implements the modified H. Hirschmuller algorithm [HH08] that differs from the original one as follows:

• By default, the algorithm is single-pass, which means that you consider only 5 directions instead of 8. Set fullDP=true to run the full variant of the algorithm but beware that it may consume a lot of memory.
• The algorithm matches blocks, not individual pixels. Though, setting SADWindowSize=1 reduces the blocks to single pixels.
• Mutual information cost function is not implemented. Instead, a simpler Birchfield-Tomasi sub-pixel metric from [BT98] is used. Though, the color images are supported as well.
• Some pre- and post- processing steps from K. Konolige algorithm :ocv:funcx:"StereoBM.operator()" are included, for example: pre-filtering (CV_STEREO_BM_XSOBEL type) and post-filtering (uniqueness check, quadratic interpolation and speckle filtering).

Note:

• (Python) An example illustrating the use of the StereoSGBM matching algorithm can be found at opencv_source_code/samples/python2/stereo_match.py

See Also:

org.opencv.calib3d.StereoSGBM

Field Summary

Fields

Modifier and Type	Field and Description
static int	DISP_SCALE
static int	DISP_SHIFT
protected long	nativeObj

Constructor Summary

Constructors

Modifier	Constructor and Description
	StereoSGBM() Initializes StereoSGBM and sets parameters to custom values.??
	StereoSGBM(int minDisparity, int numDisparities, int SADWindowSize) Initializes StereoSGBM and sets parameters to custom values.??
	StereoSGBM(int minDisparity, int numDisparities, int SADWindowSize, int P1, int P2, int disp12MaxDiff, int preFilterCap, int uniquenessRatio, int speckleWindowSize, int speckleRange, boolean fullDP) Initializes StereoSGBM and sets parameters to custom values.??
protected	StereoSGBM(long addr)

Method Summary

Methods

Modifier and Type	Method and Description
void	compute(Mat left, Mat right, Mat disp)
protected void	finalize()
int	get_disp12MaxDiff()
boolean	get_fullDP()
int	get_minDisparity()
int	get_numberOfDisparities()
int	get_P1()
int	get_P2()
int	get_preFilterCap()
int	get_SADWindowSize()
int	get_speckleRange()
int	get_speckleWindowSize()
int	get_uniquenessRatio()
void	set_disp12MaxDiff(int disp12MaxDiff)
void	set_fullDP(boolean fullDP)
void	set_minDisparity(int minDisparity)
void	set_numberOfDisparities(int numberOfDisparities)
void	set_P1(int P1)
void	set_P2(int P2)
void	set_preFilterCap(int preFilterCap)
void	set_SADWindowSize(int SADWindowSize)
void	set_speckleRange(int speckleRange)
void	set_speckleWindowSize(int speckleWindowSize)
void	set_uniquenessRatio(int uniquenessRatio)

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

nativeObj

protected final long nativeObj

DISP_SHIFT

public static final int DISP_SHIFT

See Also:

Constant Field Values

DISP_SCALE

public static final int DISP_SCALE

See Also:

Constant Field Values

Constructor Detail

StereoSGBM

protected StereoSGBM(long addr)

StereoSGBM

public StereoSGBM()

Initializes StereoSGBM and sets parameters to custom values.??

The first constructor initializes StereoSGBM with all the default parameters. So, you only have to set StereoSGBM.numberOfDisparities at minimum. The second constructor enables you to set each parameter to a custom value.

See Also:

org.opencv.calib3d.StereoSGBM.StereoSGBM

StereoSGBM

public StereoSGBM(int minDisparity,
          int numDisparities,
          int SADWindowSize,
          int P1,
          int P2,
          int disp12MaxDiff,
          int preFilterCap,
          int uniquenessRatio,
          int speckleWindowSize,
          int speckleRange,
          boolean fullDP)

Initializes StereoSGBM and sets parameters to custom values.??

The first constructor initializes StereoSGBM with all the default parameters. So, you only have to set StereoSGBM.numberOfDisparities at minimum. The second constructor enables you to set each parameter to a custom value.

Parameters:

minDisparity - Minimum possible disparity value. Normally, it is zero but sometimes rectification algorithms can shift images, so this parameter needs to be adjusted accordingly.

numDisparities - Maximum disparity minus minimum disparity. The value is always greater than zero. In the current implementation, this parameter must be divisible by 16.

SADWindowSize - Matched block size. It must be an odd number >=1. Normally, it should be somewhere in the 3..11 range.

P1 - The first parameter controlling the disparity smoothness. See below.

P2 - The second parameter controlling the disparity smoothness. The larger the values are, the smoother the disparity is. P1 is the penalty on the disparity change by plus or minus 1 between neighbor pixels. P2 is the penalty on the disparity change by more than 1 between neighbor pixels. The algorithm requires P2 > P1. See stereo_match.cpp sample where some reasonably good P1 and P2 values are shown (like 8*number_of_image_channels*SADWindowSize*SADWindowSize and 32*number_of_image_channels*SADWindowSize*SADWindowSize, respectively).

disp12MaxDiff - Maximum allowed difference (in integer pixel units) in the left-right disparity check. Set it to a non-positive value to disable the check.

preFilterCap - Truncation value for the prefiltered image pixels. The algorithm first computes x-derivative at each pixel and clips its value by [-preFilterCap, preFilterCap] interval. The result values are passed to the Birchfield-Tomasi pixel cost function.

uniquenessRatio - Margin in percentage by which the best (minimum) computed cost function value should "win" the second best value to consider the found match correct. Normally, a value within the 5-15 range is good enough.

speckleWindowSize - Maximum size of smooth disparity regions to consider their noise speckles and invalidate. Set it to 0 to disable speckle filtering. Otherwise, set it somewhere in the 50-200 range.

speckleRange - Maximum disparity variation within each connected component. If you do speckle filtering, set the parameter to a positive value, it will be implicitly multiplied by 16. Normally, 1 or 2 is good enough.

fullDP - Set it to true to run the full-scale two-pass dynamic programming algorithm. It will consume O(W*H*numDisparities) bytes, which is large for 640x480 stereo and huge for HD-size pictures. By default, it is set to false.

See Also:

org.opencv.calib3d.StereoSGBM.StereoSGBM

StereoSGBM

public StereoSGBM(int minDisparity,
          int numDisparities,
          int SADWindowSize)

Initializes StereoSGBM and sets parameters to custom values.??

The first constructor initializes StereoSGBM with all the default parameters. So, you only have to set StereoSGBM.numberOfDisparities at minimum. The second constructor enables you to set each parameter to a custom value.

Parameters:

minDisparity - Minimum possible disparity value. Normally, it is zero but sometimes rectification algorithms can shift images, so this parameter needs to be adjusted accordingly.

numDisparities - Maximum disparity minus minimum disparity. The value is always greater than zero. In the current implementation, this parameter must be divisible by 16.

SADWindowSize - Matched block size. It must be an odd number >=1. Normally, it should be somewhere in the 3..11 range.

See Also:

org.opencv.calib3d.StereoSGBM.StereoSGBM

Method Detail

compute

public void compute(Mat left,
           Mat right,
           Mat disp)

get_minDisparity

public int get_minDisparity()

set_minDisparity

public void set_minDisparity(int minDisparity)

get_numberOfDisparities

public int get_numberOfDisparities()

set_numberOfDisparities

public void set_numberOfDisparities(int numberOfDisparities)

get_SADWindowSize

public int get_SADWindowSize()

set_SADWindowSize

public void set_SADWindowSize(int SADWindowSize)

get_preFilterCap

public int get_preFilterCap()

set_preFilterCap

public void set_preFilterCap(int preFilterCap)

get_uniquenessRatio

public int get_uniquenessRatio()

set_uniquenessRatio

public void set_uniquenessRatio(int uniquenessRatio)

get_P1

public int get_P1()

set_P1

public void set_P1(int P1)

get_P2

public int get_P2()

set_P2

public void set_P2(int P2)

get_speckleWindowSize

public int get_speckleWindowSize()

set_speckleWindowSize

public void set_speckleWindowSize(int speckleWindowSize)

get_speckleRange

public int get_speckleRange()

set_speckleRange

public void set_speckleRange(int speckleRange)

get_disp12MaxDiff

public int get_disp12MaxDiff()

set_disp12MaxDiff

public void set_disp12MaxDiff(int disp12MaxDiff)

get_fullDP

public boolean get_fullDP()

set_fullDP

public void set_fullDP(boolean fullDP)

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable