Package boofcv.alg.disparity.sgm

Class SgmStereoDisparityHmi

java.lang.Object

boofcv.alg.disparity.sgm.SgmStereoDisparity<T,T>

boofcv.alg.disparity.sgm.SgmStereoDisparityError<GrayU8>

boofcv.alg.disparity.sgm.SgmStereoDisparityHmi

public class SgmStereoDisparityHmi
extends SgmStereoDisparityError<GrayU8>

Estimates stereo disparity using Semi Global Matching and Hierarchical Mutual Information Cost. This is intended to be a faithful reproduction of the algorithm described in [1] with no significant deviations.

SGM works by computing the path cost along (2,4,8, or 16) directions for each pixel. These costs are summed up and the path which minimizes the total cost is selected. By considering multiple paths along different directions it avoids the pitfalls of earlier approaches, such as dynamic programming along the x-axis only. It is also by far faster than globally optimal approaches but slower then approaches such as block matching

MI cost requires prior information to compute. If the disparity is known then MI can be found. However, we want to find the disparity using MI. To get around this problem a pyramidal approach is used to estimate MI. The MI cost is initially assigned random values. This is then used to estimate the disparity at the lowest resolution image in the pyramid. The found disparity is used to update the MI estimate. This process is repeated until it reaches the highest resolution layer. By this point it should have a good model for MI.

See Also:

• StereoMutualInformation
• SgmCostAggregation

• [1] Hirschmuller, Heiko. "Stereo processing by semiglobal matching and mutual information." IEEE Transactions on pattern analysis and machine intelligence 30.2 (2007): 328-341.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	extraIterations
protected PyramidDiscreteNN2<GrayU8>	pyrLeft
protected PyramidDiscreteNN2<GrayU8>	pyrRight
protected Random	rand
protected StereoMutualInformation	stereoMI

Fields inherited from class boofcv.alg.disparity.sgm.SgmStereoDisparity

aggregation, costYXD, disparity, disparityMin, disparityRange, helper, score, selector, sgmCost

Constructor Summary

Constructors

Constructor	Description
SgmStereoDisparityHmi(ConfigDiscreteLevels configPyr, StereoMutualInformation stereoMI, SgmDisparitySelector selector)	Provides configurations and internal implementations of different components
SgmStereoDisparityHmi(ConfigDiscreteLevels configPyr, StereoMutualInformation stereoMI, SgmDisparitySelector selector, SgmCostFromBlocks<GrayU8> blockScore)

Method Summary

Modifier and Type	Method	Description
int	getExtraIterations()
PyramidDiscreteNN2<GrayU8>	getPyrLeft()
PyramidDiscreteNN2<GrayU8>	getPyrRight()
StereoMutualInformation	getStereoMI()
void	process(GrayU8 left, GrayU8 right)	Computes disparity using pyramidal mutual information.
void	process(GrayU8 left, GrayU8 right, GrayU8 disparityEst, int invalid)	Computes disparity from an initial disparity estimate.
void	setExtraIterations(int extraIterations)

Methods inherited from class boofcv.alg.disparity.sgm.SgmStereoDisparity

getInvalidDisparity, saveScore, subpixel

Methods inherited from class java.lang.Object

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

Field Details

rand

protected Random rand

stereoMI

protected StereoMutualInformation stereoMI

extraIterations

protected int extraIterations

pyrLeft

protected PyramidDiscreteNN2<GrayU8> pyrLeft

pyrRight

protected PyramidDiscreteNN2<GrayU8> pyrRight

Constructor Details

SgmStereoDisparityHmi

public SgmStereoDisparityHmi(ConfigDiscreteLevels configPyr,
 StereoMutualInformation stereoMI,
 SgmDisparitySelector selector)

Provides configurations and internal implementations of different components

Parameters:

configPyr - Specifies number of layers in the pyramid

stereoMI - Computes mutual information from a stereo pair with known disparity

selector - Selects the best disparity given the cost

SgmStereoDisparityHmi

public SgmStereoDisparityHmi(ConfigDiscreteLevels configPyr,
 StereoMutualInformation stereoMI,
 SgmDisparitySelector selector,
 SgmCostFromBlocks<GrayU8> blockScore)

Method Details

process

public void process(GrayU8 left,
 GrayU8 right)

Computes disparity using pyramidal mutual information.

Overrides:

process in class SgmStereoDisparityError<GrayU8>

Parameters:

left - (Input) left rectified stereo image

right - (Input) right rectified stereo image

process

public void process(GrayU8 left,
 GrayU8 right,
 GrayU8 disparityEst,
 int invalid)

Computes disparity from an initial disparity estimate. A pyramid is not required because of the initial disparity estimate. This function can be called iteratively to improve the estimate.

Parameters:

left - (Input) left rectified stereo image

right - (Input) right rectified stereo image

disparityEst - (Input) Initial disparity estimate used to compute MI

getStereoMI

public StereoMutualInformation getStereoMI()

getPyrLeft

public PyramidDiscreteNN2<GrayU8> getPyrLeft()

getPyrRight

public PyramidDiscreteNN2<GrayU8> getPyrRight()

getExtraIterations

public int getExtraIterations()

setExtraIterations

public void setExtraIterations(int extraIterations)