Inertia2d

Measure allowing to compute the second order moment for 2d shape. More...

Classes
class	ipsdk::imaproc::shape::analysis::Inertia2dMsr
	Measurement object for measure Inertia2d. More...
class	ipsdk::imaproc::shape::analysis::Inertia2dMsrInfo
	Information object for measure Inertia2d. More...
class	ipsdk::imaproc::shape::analysis::Inertia2dMsrResults
	Measurement results object for measure Inertia2d. More...

Detailed Description

Measure allowing to compute the second order moment for 2d shape.

The Inertia2d measurement computes the second order central moment for each shape, without taking the pixels intensities into consideration.

It is equivalent to GreyInertia with all pixels intensities set to 1 in 2d case.

Here is an example of the inertia calculated from an input image :

See also

https://en.wikipedia.org/wiki/Image_moment#Central_moments

Author

R. Abbal

Date

2015/07/29

Copyright

2015 Reactiv'IP, all right reserved.

Measure allowing to compute the second order moment for 2d shape

Measure synthesis :

Measure Type	Measure Unit Type	Parameter Type	Result Type	Shape Requirements
Geometry 2d	None	None	Custom	Row Intersections

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 Inertia2d is not associated to any unit [ipsdk::shape::analysis::eMsrUnitFormat::eMUF_NoUnit]

Measure Parameter Type :

Measure Inertia2d has no parameters

Measure Result Type :

Measure Inertia2d is associated to Inertia2dMsrResults results

Measure Shape Requirements :

Measure Inertia2d requires row intersections from shape data

Measure Dependencies :

Measure Inertia2d depends on following measures :

Measure Mode	Measure Name	Measure Type	Measure Parameters
eMVP_2d	Barycenter	Barycenter2d

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, "Inertia2dMsr")
    
    #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("Inertia2dMsr")
    
    # retrieve measure values
    outMsrValues = outMsr.getMeasureResult().getColl(0)
    print("First label inertia mxx component measurement equal " + str(outMsrValues[1].mxx()))

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, "Inertia2dMsr");
    
    // compute measure on shape 2d collection
    MeasureSetPtr pOutMeasureSet = shapeAnalysis2d(pInGreyImg2d, pShape2dColl, pMeasureInfoSet);

    // retrieve associated results
    const MeasureConstPtr& pInertia2dOutMsr = pOutMeasureSet->getMeasure("Inertia2dMsr");
    const Inertia2dMsrResults& outResults = static_cast<const Inertia2dMsrResults&>(pInertia2dOutMsr->getMeasureResult());