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# prapi::transforms::CircularHough< T, graphics::Point< double > > Class Template Reference

`#include <Hough.h>`

Inheritance diagram for prapi::transforms::CircularHough< T, graphics::Point< double > >:

List of all members.

## Detailed Description

### template<class T> class prapi::transforms::CircularHough< T, graphics::Point< double > >

The circular Hough transform for gradient images.

The algorithm used here is a modified version of the one typically found in computer vision textbooks. Instead of blindly trusting the given gradient directions, an error term can be given to indicate the trustworthness of the gradient estimates. Since gradients are typically measured with 3x3 masks, they cannot be very accurate. When a measure of the angular error is involved, the transformation method assumes the real value of the gradient is normally distributed around the given angle estimate. The width of the distribution is dependent on the error estimate.

## Public Methods

Create an instance of the circular Hough transform.

void setThreshold (double threshold)
Set the threshold.

double getThreshold () const
Get the current threshold.

void setRadii (int start, int end, double step)
Set the radii that the transform looks for, and the sampling step.

Get the sampling step.

util::Matrix< T > getTransformedImage (const util::Matrix< graphics::Point< double > > &mat) throw (ImageTransformException&)

## Member Function Documentation

 template prapi::transforms::CircularHough< T, graphics::Point< double > >::CircularHough ( double magnitudeThreshold, int startRadius = 1, int endRadius = -1, double radiusStep = 1, double gradientError = 0 ) ` [inline]`

Create an instance of the circular Hough transform.