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Module: MetrologyBasic

Locates the strongest dark or bright pixel peak along a given path (without a scan map).


Very fast detection of a thin structure like a wire or a scale mark.
Name Type Range Description
Input value
inImage Image Input image
Input value
inScanPath Path Path along which the scan is performed
Input value
inScanPathAlignment CoordinateSystem2D* Adjusts the scan path to the position of the inspected object
Input value
inScanWidth Integer 1 - Width of the 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 the resulting ridge
Input value
inLocalBlindness LocalBlindness* Defines conditions in which weaker ridges can be detected in the vicinity of stronger ridges
Output value
outRidge Ridge1D? Found ridge
Output value
outAlignedScanPath Path Transformed input path
Diagnostic input
diagBrightnessProfile Profile Extracted image profile
Diagnostic input
diagResponseProfile Profile Profile of the ridge operator response
Diagnostic input
diagSamplingPoints PathArray Array of paths each one containing the sampling points that contributes to a single value of the extracted profile
Diagnostic input
diagSamplingStep Real Used distance between consecutive sampling points on the scan path


The operation scans the image along inScanPath and locates the strongest ridge of the given characteristics. If there is no such ridge then the outputs are set to NIL.

The optional parameter inScanPathAlignment defines a transform to be performed on the inScanPath so that the actual scan path (outAlignedScanPath) is adjusted to the position of the object, typically detected by one of Template Matching filters.


  • Connect an input image to the inImage input.
  • Create inScanPath which is more or less perpendicular to the ridges you want to detect. It should be long enough to anticipate all possible ridge locations.
  • Adjust inRidgeScanParams.RidgeWidth to the expected thickness of the ridge (in pixels).
  • Define inRidgeScanParams.RidgePolarity to detect a particular ridge type, and only that type.
  • Use a local coordinate system connected to inScanPathAlignment to automatically adjust the measurement to variable object position (optional).
  • If the noise level is high, try increasing inScanWidth and/or inRidgeScanParams.SmoothingStdDev.
  • If no ridge is found, try decreasing inRidgeScanParams.MinMagnitude.
  • For difficult cases try different settings of the inRidgeScanParams.RidgeOperator parameter.


ScanSingleRidge locates the strongest ridge across inScanPath.


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

This filter is a part of the 1D Edge Detection toolset. For a comprehensive introduction to this technique please refer to 1D Edge Detection and 1D Edge Detection - Subpixel Precision chapters of our Machine Vision Guide.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of ScanRidges filter group.

See Also

  • ScanMultipleRidges – Locates multiple dark or bright pixel peaks along a given path (without a scan map).
  • ScanExactlyNRidges – Locates a specified number of the strongest dark or bright pixel peak along a given path (without a scan map).
  • ScanSingleRidge – Locates the strongest dark or bright pixel peak along a given path (without a scan map).