Convexity

Measure the convexity of a shape. More...

Classes
class	ipsdk::imaproc::shape::analysis::ConvexityMsr
	Measurement object for measure Convexity. More...
class	ipsdk::imaproc::shape::analysis::ConvexityMsrInfo
	Information object for measure Convexity. More...

Typedefs
typedef HolesBasicPolicyMsrParams	ipsdk::imaproc::shape::analysis::ConvexityMsrParams
	parameter type associated to class

Detailed Description

Measure the convexity of a shape.

Convexity measure computes the convexity of a shape, that equals to the volume (resp. area) of the 3d (resp. 2d) shape divided by the volume (resp. area) of its convex hull.

This measure is also known as 'Solidity'.

Here is an example of convexity measurement, with "consider holes" parameter set to 'true':

Author

H. Delestre

Date

2015/07/21

Copyright

2015 Reactiv'IP, all right reserved.

Measure the convexity of a shape

Measure synthesis :

Measure Type	Measure Unit Type	Parameter Type	Result Type	Shape Requirements
Generic	None	ConvexityMsrParams	Value (ipsdk::ipReal64)	Boundary Approximation

See Shape measurement for additional information on these pictograms

Measure Type :

This is a generic measure

• it does not directly use shape or image data
• it can use dependencies to other measures to compute a result (see Measure Dependencies section)

This measure can be used in 2d and 3d case

Measure Unit Type:

Measure Convexity is not associated to any unit [ipsdk::shape::analysis::eMsrUnitFormat::eMUF_NoUnit]

Measure Parameter Type :

Measure Convexity is associated to ConvexityMsrParams parameters

Measure Result Type :

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

Measure Shape Requirements :

Measure Convexity requires boundary approximation from shape data

Measure Dependencies :

Measure Convexity depends on following measures :

Measure Mode	Measure Name	Measure Type	Measure Parameters
eMVP_2d	Volume	PolygonArea2d	createHolesBasicPolicyMsrParams(_pMsrParams->getValue<ConvexityMsrParams::ProcessHoles>())
eMVP_3d	Volume	MeshVolume3d	createHolesBasicPolicyMsrParams(_pMsrParams->getValue<ConvexityMsrParams::ProcessHoles>())
eMVP_2d	ConvexHullVolume	ConvexHullArea2d
eMVP_3d	ConvexHullVolume	ConvexHullVolume3d

Note

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

See Shape Analysis 3d for more information on general shape 3d 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, "ConvexityMsr")
    
    #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("ConvexityMsr")
    
    # retrieve measure values
    outMsrValues = outMsr.getMeasureResult().getColl(0)
    print("First label measurement equal " + str(outMsrValues[1]))

Generic example in 3d case :

import PyIPSDK
import PyIPSDK.IPSDKIPLShapeAnalysis as shapeanalysis

    # Create the infoset
    inMeasureInfoSet3d = PyIPSDK.createMeasureInfoSet3d()
    PyIPSDK.createMeasureInfo(inMeasureInfoSet3d, "ConvexityMsr")
    
    #Perform the analysis
    outMeasureSet = shapeanalysis.labelAnalysis3d(inGreyImg, inLabelImg, inMeasureInfoSet3d)
    
    # save results to csv format
    PyIPSDK.saveCsvMeasureFile(os.path.join(tmpPath,  "shape_analysis_results.csv"), outMeasureSet)
    
    # retrieve measure results
    outMsr = outMeasureSet.getMeasure("ConvexityMsr")
    
    # 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>();
    readFromXmlFile(inputShape2dCollPath, *pShape2dColl);

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

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