Gradient angularity index 2d

measure allowing to compute average of the change in the angles of the gradient vectors around the particle circumference More...

Classes
class	ipsdk::imaproc::shape::analysis::GradientAngularityIndex2dMsr
	Measurement object for measure GradientAngularityIndex2d. More...
class	ipsdk::imaproc::shape::analysis::GradientAngularityIndex2dMsrInfo
	Information object for measure GradientAngularityIndex2d. More...

Detailed Description

measure allowing to compute average of the change in the angles of the gradient vectors around the particle circumference

This measure allows to quantified the angularity of a shape using the change in the angles of the gradient vectors around the shape boundary.

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

where :

• is the length of segment starting at considered top .
• is the angle of the normal vector associated to segment starting at considered top .
  

Then the global shape angularity value is simply given by the normalized sum of previous values over all tops of the polygonal approximation of shape :

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

See also

Al-Rousan, T., Masad, T., Tutumluer, E. and Pan T. (2007). Evaluation of image analysis techniques for quantifying aggregate shape characteristics.Construction and building materials21, pp. 978-990.

Masad, E., Al-Rousan, T., Button, J., Little, D. and Tutumluer, E. (2007). Test methods for characterizing aggregate shape, texture, and angularity. National Cooperative Highway Research Program (NCHRP) Report 555. Transportation Research Board, Washington, D.C.

Lees, G. (1964) A new method for determining the angularity of particles. Sedimentology, 3, pp. 2-21.

Taleb Al-Rousan, Eyad Masad, Erol Tutumluer, Tongyan Pan, Evaluation of image analysis techniques for quantifying aggregate shape characteristics, Construction and Building Materials 21 (2007) 978-990.

Tafesse Solomon, Sun Wenjuan, Fernlund Joanne, and Linbing Wang, A new image analysis technique to quantify particle angularity, Engineering Geology and Geophysics Research Group Royal Institute of Technology (KTH)

Author

E.Noirfalise

Date

2017/07/18

Copyright

2017 Reactiv'IP, all right reserved.

measure allowing to compute average of the change in the angles of the gradient vectors around the particle circumference

Measure synthesis :

Measure Type	Measure Unit Type	Parameter Type	Result Type	Shape Requirements
Geometry 2d	Custom	None	Value (ipsdk::ipReal64)	Boundary Approximation

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 GradientAngularityIndex2d is associated to a custom unit, please see definition of GradientAngularityIndex2dInfo::computeCustomMsrUnitStr function [ipsdk::shape::analysis::eMsrUnitFormat::eMUF_CustomUnit]

Measure Parameter Type :

Measure GradientAngularityIndex2d has no parameters

Measure Result Type :

Measure GradientAngularityIndex2d is associated to ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64> results

Measure Shape Requirements :

Measure GradientAngularityIndex2d requires boundary approximation from shape data

Measure Dependencies :

Measure GradientAngularityIndex2d has no dependency

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, "EdgeAngularity2dMsr")
    
    #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("EdgeAngularity2dMsr")
    
    # 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, "GradientAngularityIndex2dMsr");
    
    // compute measure on shape 2d collection
    MeasureSetPtr pOutMeasureSet = shapeAnalysis2d(pInGreyImg2d, pShape2dColl, pMeasureInfoSet);

    // retrieve associated results
    const MeasureConstPtr& pGradientAngularityIndex2dOutMsr = pOutMeasureSet->getMeasure("GradientAngularityIndex2dMsr");
    const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>& outResults = static_cast<const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>&>(pGradientAngularityIndex2dOutMsr->getMeasureResult());