Disparity angularity 2d

measure allowing to build an histogram of disparity between angle measured on shape and angle measured on reference ellipse More...

Classes
class	ipsdk::imaproc::shape::analysis::DisparityAngularity2dMsr
	Measurement object for measure DisparityAngularity2d. More...
class	ipsdk::imaproc::shape::analysis::DisparityAngularity2dMsrInfo
	Information object for measure DisparityAngularity2d. More...
class	ipsdk::imaproc::shape::analysis::DisparityAngularity2dMsrParams
	Parameter object for measure DisparityAngularity2d. More...

Detailed Description

measure allowing to build an histogram of disparity between angle measured on shape and angle measured on reference ellipse

This measure allows to quantified the angularity of a shape using the difference between angle of consecutive segments of polygonal approximation of shape with angle on its equivalent ellipse.

Note that equivalent ellipse associated to a shape is define such as :

• ellipse center is set at shape barycenter (see Barycenter2d)
• ellipse orientation is equal to orientation extracted from second order moment of shape (see Inertia Orientation 2d)
• ellipse dimensions are defined such that ellipse perimeter and area match with shape perimeter (see Perimeter2d) and shape area (see Area2d).

For each tops of the polygonal approximation of shape, we compute an angularity value given by :

where :

• is angle between segments ending at considered top .
• is the associated angle on equivalent ellipse.
  

We then compute the histogram of these values using a number of orientation defined by parameter NbOrientations.

The global shape angularity value is then given by mean value associated to bin containing quantile value defined by parameter Quantile.

Here is an example of degree of angularity 2d computation on few caracteristic shapes :

Author

E.Noirfalise

Date

2017/07/21

Copyright

2017 Reactiv'IP, all right reserved.

measure allowing to build an histogram of disparity between angle measured on shape and angle measured on reference ellipse

Measure synthesis :

Measure Type	Measure Unit Type	Parameter Type	Result Type	Shape Requirements
Geometry 2d	Angle	DisparityAngularity2dMsrParams	Value (ipsdk::ipReal64)	Both

See Shape measurement for additional information on these pictograms

Measure Type :

This is a geometry 2d measure

• it use shape 2d data to compute a result
• it optionally can use dependencies to other measures to compute a result (see Measure Dependencies section)

This measure can only be used in 2d case

Measure Unit Type:

Measure DisparityAngularity2d is associated to an angular (radians) measurement unit [ipsdk::shape::analysis::eMsrUnitFormat::eMUF_RadianUnit]

Measure Parameter Type :

Measure DisparityAngularity2d is associated to DisparityAngularity2dMsrParams parameters

Measure Result Type :

Measure DisparityAngularity2d is associated to ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64> results

Measure Shape Requirements :

Measure DisparityAngularity2d requires row intersections and boundary approximation from shape data

Measure Dependencies :

Measure DisparityAngularity2d depends on following measures :

Measure Mode	Measure Name	Measure Type	Measure Parameters
eMVP_2d	Perimeter2d	Perimeter2d	createHolesBasicPolicyMsrParams(_pMsrParams->getValue<DisparityAngularity2dMsrParams::ProcessHoles>())
eMVP_2d	Area2d	PolygonArea2d	createHolesBasicPolicyMsrParams(_pMsrParams->getValue<DisparityAngularity2dMsrParams::ProcessHoles>())
eMVP_2d	Barycenter2d	Barycenter2d
eMVP_2d	InertiaOrientation2d	InertiaOrientation2d

Note

See Shape Analysis 2d for more information on general shape 2d analysis and measurement usage.

Example of Python code :

Generic example in 2d case :

import PyIPSDK
import PyIPSDK.IPSDKIPLShapeAnalysis as shapeanalysis

    # Create the infoset
    inMeasureInfoSet2d = PyIPSDK.createMeasureInfoSet2d()
    PyIPSDK.createMeasureInfo(inMeasureInfoSet2d, "GradientAngularityIndex2dMsr")
    
    #Perform the analysis
    outMeasureSet = shapeanalysis.labelAnalysis2d(inGreyImg, inLabelImg2d, inMeasureInfoSet2d)
    
    # save results to csv format
    PyIPSDK.saveCsvMeasureFile(os.path.join(tmpPath,  "shape_analysis_results.csv"), outMeasureSet)
    
    # retrieve measure results
    outMsr = outMeasureSet.getMeasure("GradientAngularityIndex2dMsr")
    
    # retrieve measure values
    outMsrValues = outMsr.getMeasureResult().getColl(0)
    print("First label measurement equal " + str(outMsrValues[1]))

Example of C++ code :

Example informations

Associated library

IPSDKIPLShapeAnalysis

Code Example

    // opening grey level input image
    ImagePtr pInGreyImg2d = loadTiffImageFile(inputGreyImgPath);

    // read entity shape 2d collection used for processing
    Shape2dCollPtr pShape2dColl = boost::make_shared<Shape2dColl>();
    IPSDK_REQUIRE(readFromXmlFile(inputShape2dCollPath, *pShape2dColl) == true);

    // define a measure info set
    MeasureInfoSetPtr pMeasureInfoSet = MeasureInfoSet::create2dInstance();
    createMeasureInfo(pMeasureInfoSet, "DisparityAngularity2dMsr");
    
    // compute measure on shape 2d collection
    MeasureSetPtr pOutMeasureSet = shapeAnalysis2d(pInGreyImg2d, pShape2dColl, pMeasureInfoSet);

    // retrieve associated results
    const MeasureConstPtr& pDisparityAngularity2dOutMsr = pOutMeasureSet->getMeasure("DisparityAngularity2dMsr");
    const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>& outResults = static_cast<const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>&>(pDisparityAngularity2dOutMsr->getMeasureResult());