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Further options for the transformations #14

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Merged
dzenanz merged 3 commits into from
Feb 21, 2020
Merged

Further options for the transformations #14

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0b7b9ab
ENH: option to use arc increment instead of constant angular increment
romangrothausmann Feb 19, 2020
12bbf86
ENH: option to return NaN in case alpha is outside [-pi,pi]:
romangrothausmann Feb 19, 2020
a6ee109
ENH: option for angular offset
romangrothausmann Feb 21, 2020
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17 changes: 17 additions & 0 deletions include/itkCartesianToPolarTransform.h
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Original file line number Diff line number Diff line change
Expand Up @@ -155,6 +155,21 @@ class ITK_TEMPLATE_EXPORT CartesianToPolarTransform :
itkSetMacro( Center, InputPointType );
itkGetConstReferenceMacro( Center, InputPointType );

/** Set an angular offset for the polar coordinate transform.
*
* Defaults to 0.0
*/
itkSetMacro( AngleOffset, typename OutputPointType::ValueType );
itkGetConstReferenceMacro( AngleOffset, typename OutputPointType::ValueType );

/** Enable/Disable to use constant arc increment instead of constant angular increment.
*
* Defaults to Off
*/
itkSetMacro(ConstArcIncr, bool);
itkGetMacro(ConstArcIncr, bool);
itkBooleanMacro(ConstArcIncr);

protected:
CartesianToPolarTransform();
~CartesianToPolarTransform() override;
Expand All @@ -164,6 +179,8 @@ class ITK_TEMPLATE_EXPORT CartesianToPolarTransform :

private:
InputPointType m_Center;
typename OutputPointType::ValueType m_AngleOffset = 0;
bool m_ConstArcIncr = false;
}; //class CartesianToPolarTransform

} // namespace itk
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10 changes: 8 additions & 2 deletions include/itkCartesianToPolarTransform.hxx
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Expand Up @@ -59,13 +59,19 @@ CartesianToPolarTransform<TParametersValueType, NDimensions>

const InputPointType vector = inputPoint - this->m_Center;

outputPoint[1] = std::sqrt( vector[0] * vector[0] + vector[1] * vector[1] );
outputPoint[0] = std::acos( vector[0] / outputPoint[1] );
outputPoint[1] = std::sqrt( vector[0] * vector[0] + vector[1] * vector[1] ); // r= sqrt(x^2 + y^2)
outputPoint[0] = std::acos( vector[0] / outputPoint[1] ); // alpha = acos(x/r)
outputPoint[0] += m_AngleOffset; // add offset before 2*pi adjustment to keep values within [-pi,pi]
if( vector[1] < 0.0 )
{
outputPoint[0] = Math::twopi - outputPoint[0];
}

if(m_ConstArcIncr)
{
outputPoint[0] *= outputPoint[1]; // arc= r*alpha
}

return outputPoint;
}

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26 changes: 26 additions & 0 deletions include/itkPolarToCartesianTransform.h
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Expand Up @@ -152,6 +152,29 @@ class ITK_TEMPLATE_EXPORT PolarToCartesianTransform:
itkSetMacro( Center, OutputPointType );
itkGetConstReferenceMacro( Center, OutputPointType );

/** Set an angular offset for the polar coordinate transform.
*
* Defaults to 0.0
*/
itkSetMacro( AngleOffset, typename InputPointType::ValueType );
itkGetConstReferenceMacro( AngleOffset, typename InputPointType::ValueType );

/** Enable/Disable to use constant arc increment instead of constant angular increment.
*
* Defaults to Off
*/
itkSetMacro(ConstArcIncr, bool);
itkGetMacro(ConstArcIncr, bool);
itkBooleanMacro(ConstArcIncr);

/** Enable/Disable to return NaN in case alpha is outside [-pi,pi].
*
* Defaults to Off
*/
itkSetMacro(ReturnNaN, bool);
itkGetMacro(ReturnNaN, bool);
itkBooleanMacro(ReturnNaN);

protected:
PolarToCartesianTransform();
~PolarToCartesianTransform() override;
Expand All @@ -161,6 +184,9 @@ class ITK_TEMPLATE_EXPORT PolarToCartesianTransform:

private:
OutputPointType m_Center;
typename InputPointType::ValueType m_AngleOffset = 0;
bool m_ConstArcIncr = false;
bool m_ReturnNaN = false;
}; //class PolarToCartesianTransform

} // namespace itk
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20 changes: 18 additions & 2 deletions include/itkPolarToCartesianTransform.hxx
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Expand Up @@ -56,8 +56,24 @@ PolarToCartesianTransform<TParametersValueType, NDimensions>
{
OutputPointType outputPoint(inputPoint);

outputPoint[0] = inputPoint[1] * std::cos(inputPoint[0]); //r*cos(alpha)
outputPoint[1] = inputPoint[1] * std::sin(inputPoint[0]); //r*sin(alpha)
double alpha = inputPoint[0];
if(m_ConstArcIncr)
{
alpha /= inputPoint[1]; // alpha = arc/r
}

if(m_ReturnNaN && (alpha < -Math::pi || Math::pi < alpha))
{
using PointNumericTraits = NumericTraits<typename OutputPointType::ValueType>;
outputPoint[0] = PointNumericTraits::quiet_NaN();
outputPoint[1] = PointNumericTraits::quiet_NaN();
return outputPoint;
}

alpha += m_AngleOffset; // add offset after NaN return to keep values within [-pi,pi]

outputPoint[0] = inputPoint[1] * std::cos(alpha); //r*cos(alpha)
outputPoint[1] = inputPoint[1] * std::sin(alpha); //r*sin(alpha)

for( unsigned int ii = 0; ii < SpaceDimension; ++ii )
{
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