CircleHoughTool

The CircleHoughTool searches for a circle in the set region that best matches the given parameters, within a given search interval.

The following parameters are available for configuration:

1. Magnitude Scale: For this purpose, edge information is derived from the input image using a “Sobel filter”. The Magnitude Scale parameter is used for edge enhancement.

2. Smoothness: The transformation result of the edge information into Hough space is smoothed using Gaussian filter. The smoothness parameter describes the strength of the smoothing.

3. Radius Start: Default value of the radius start value in pixels

4. Radius Step: Step size by which the radius is increased in pixels.

5. Radius Count: Number of steps by which the start value of the radius is incremented by the step size.

6. Minimum Houghmax: The accumulator value in Hough space must exceed a minimum value for each radius traversed. The Minimum Houghmax parameter is specified here as a percentage of the circumference of the associated circle.

7. Blobthreshold (Stretch Gauss): The position (center) of the circle is obtained by a blob evaluation, where the Blob Threshold parameter is to be specified as a percentage of the Hough maximum.

8. Maximum Hougharea: In order to really detect a clear, as pointed as possible expression of the “Hough response”, the parameter Maximum HoughArea is used to check that the associated blob area does not exceed the specified limit.

9. EmbeddingEnabled: With this checkbox an “averaging” (Average over all Houghaccu) over all Hough accumulators (for all passed radii) is additionally selectable.

10. Determine best blob by:

• DistHoughMaxToBlobBoundary

• DistHoughMaxToBlobCenterOfMass

• DistHoughMaxToWeightedMidpoint

• MaxBlobArea

11. Get best circle of best blob by:

• HoughMax

• CenterOfMass

• WeightedMidpoint

1. Enabled: Checkbox enables averaging over all Hough results for all radii traversed.

2. Blob Threshold: Percentage gray value specification related to the maximum smoothing.

3. Min Blobarea: Default minimum blob area in pixels

4. Intermediary images: Checkbox activates the saving of recordings under the specified path.

5. InputImage is edge image: By activating the checkbox, an edge image can already be provided as InputImage for evaluation.

6. Mutlithreading: Checkbox parallelizes processes within the CircleHoughTool for runtime optimization.

Results

The following result values are available:

1. ID

2. Radius in pixel

3. Radius

4. CenterMassX

5. CenterMassY

6. WeightedMidpointX

7. WeightedMidpointY

8. Area

9. ConnectivityLabel

10. Acircularity

11. DistToBoundary

12. DistToCenterOfMass

13. DistToWeightedMidpoint