cvHoughCircles

MLModule

author	MeVis Medical Solutions AG
package	MeVisLab/Standard
dll	MLOpenCVModules
definition	MLOpenCVModules.def

Purpose

The cvHoughCircles performs the OpenCV 2D “Hough circles” algorithm.

It detects circles on each 2D slice of the given volume and generates markers with the centers and radii of the detected circles. The radius is stored in the direction component of the vector, orthogonal to the 2D slice. The markers are stored in world coordinates. A good way to visualize the markers is to use a SoView2DMarkerEditor with drawMode set to Disc, as shown in the example module.

Internally, the module only supports the uint8 data type; all input data is rescaled to the range 0-255.

Windows

Default Panel

Input Fields

input0

name: input0, type: Image

Output Fields

outCircles

name: outCircles, type: XMarkerList(MLBase)

For accessing this object via scripting see the Scripting Reference: MLXMarkerListWrapper.

Parameter Fields

Field Index

Accumulator Ratio: Double

Accumulator Threshold: Double

Apply: Trigger

Canny Threshold: Double

Max Radius: Integer

Min Distance: Double

Min Radius: Integer

Visible Fields

Min Distance

name: minDistance, type: Double, default: 10

Sets the minimum distance between detected circle centers.

Min Radius

name: minRadius, type: Integer, default: 0

Sets the minimum radius of detected circles.

Max Radius

name: maxRadius, type: Integer, default: 0

Sets the maximum radius of detected circles.

A value of 0 means the maximum radius is not limited.

Canny Threshold

name: cannyThreshold, type: Double, default: 100

Sets the threshold for the canny edge detection (in rescaled 8-bit range).

Accumulator Ratio

name: accumulatorRatio, type: Double, default: 1

Sets the resolution of the accumulator.

A value of 0.5 means the accumulator has half the resolution of the image.

Accumulator Threshold

name: accumulatorThreshold, type: Double, default: 100

Sets the accumulator threshold for detecting a circle.

The smaller the value, the more false circles may be detected. Circles corresponding to larger accumulator values will be returned first.

Apply

name: apply, type: Trigger

When pressed, circle detection is applied.