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FitSegmentToRidges

Basic

Module: MetrologyPro

Performs a series of 1D ridge detections and finds a segment that best matches the detected points.

Applications

Precise detection of a thin straight line, whose rough location is known beforehand.
Name Type Range Description
Input value
 inImage Image Image to fit segment to
Input value
 inFittingField SegmentFittingField Segment fitting field
Input value
 inFittingFieldAlignment CoordinateSystem2D* Adjusts the fitting field to the position of the inspected object
Input value
 inScanCount Integer 3 - The number of points that will be searched to estimate the position of the segment
Input value
 inScanWidth Integer 1 - The width of each scan field (in pixels)
Input value
 inSamplingParams SamplingParams Parameters controlling the sampling process
Input value
 inRidgeScanParams RidgeScanParams Parameters controlling the ridge extraction process
Input value
 inRidgeSelection Selection Selection mode of ridges
Input value
 inLocalBlindness LocalBlindness* Defines conditions in which weaker ridges can be detected in the vicinity of stronger ridges
Input value
 inMaxIncompleteness Real 0.0 - 0.999 Maximal fraction of ridge points not found
Input value
 inOutlierSuppression LineMEstimator* Selects a method for ignoring incorrectly detected points
Output value
 outSegment Segment2D? Fitted segment or nothing if the fitting fails
Output value
 outRidges Ridge1D?Array Found ridges
Output value
 outDeviationProfile Profile? Profile of distances between the actual segment points and the corresponding reference segment points
Output value
 outAlignedFittingField SegmentFittingField Fitting field used; in the image coordinate system
Output value
 outInliers Point2DArray Points matching the fitting segment
Output value
 outBrightnessProfiles ProfileArray Extracted image profiles
Output value
 outResponseProfiles ProfileArray Profiles of the ridge operator response
Diagnostic input
 diagScanSegments Segment2DArray Segments along which the scans were run
Diagnostic input
 diagSamplingAreas Rectangle2DArray Areas from which the input image is sampled

Description

The operation tries to fit a given segment to ridges present in the inImage image. Internally, it performs a series of scans with the ScanSingleRidge filter along inScanCount specific scan segments which length is always equal to the inFittingField width and cannot be less than 4. The found points are then used to determine the actual position of the segment in the image. Only inMaxIncompleteness fraction of these scans may fail. If the fitting according to the given parameters is not possible, outSegment is set to Nil.

Hints

  • Connect an input image to the inImage input.
  • If the object location is variable, connect inFittingFieldAlignment to an appropriate local coordinate system (e.g. from a template matching filter).
  • Define the inFittingField input to specify the area in which ridge scanning will be performed.
  • Define inRidgeScanParams.RidgePolarity to detect a particular ridge type, and only that type.
  • Adjust inRidgeScanParams.RidgeWidth to the expected thickness of the ridge (in pixels).
  • If the noise level is high, try increasing inScanWidth and/or inRidgeScanParams.SmoothingStdDev.
  • If no or too few ridge points are found, try decreasing inRidgeScanParams.MinMagnitude.
  • If some of the scans may fail, set the inMaxIncompleteness input accordingly.
  • If some of the scans may produce false results, try different values of the inOutlierSuppression input.
  • Use the diagScanSegments and outRidges outputs to visualize the scanning results.

Examples

Fitting a segment to a line on an object
(inRidgeScanParams.RidgePolarity = Dark).

Remarks

Read more about Local Coordinate Systems in Machine Vision Guide: Local Coordinate Systems.

This filter is a part of the Shape Fitting toolset. To read more about this technique, one can refer to the Shape Fitting chapter of our Machine Vision Guide

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of FitSegment filter group.

See Also

  • FitSegmentToEdges – Performs a series of 1D edge detections and finds a segment that best matches the detected points.
  • FitSegmentToStripe – Performs a series of 1D stripe detections and finds a segment that best matches the detected points.