cvHoughCircles

MLModule

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

Purpose

The cvHoughCircles offers the OpenCV 2D HoughCircles algorithm. It detects circles on each 2D slice of the given volume and generates markers with the detected circle centers and radius. 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 “Disc”, as shown in the example module.

Internally the module only supports the MLuint8 datatype, 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

The minimum distance between detected circle centers.

Min Radius

name: minRadius, type: Integer, default: 0

The minimum radius of detected circles.

Max Radius

name: maxRadius, type: Integer, default: 0

The maximum radius of detected circles. 0 means the maximum radius is not limited.

Canny Threshold

name: cannyThreshold, type: Double, default: 100

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

Accumulator Ratio

name: accumulatorRatio, type: Double, default: 1

The resolution of the accumulator (0.5 means the accumulator has half the resolution of the image)

Accumulator Threshold

name: accumulatorThreshold, type: Double, default: 100

The accumulator threshold for detecting a circle. The smaller it is, the more false circles may be detected. Circles, corresponding to the larger accumulator values, will be returned first.

Apply

name: apply, type: Trigger

Runs the circle detection.