Back to Adaptive Vision Studio website

You are here: Start » Filter Reference » 1D Edge Detection 3D » ScanSingleEdge3D


Locates the strongest change of surface height along a given path.

Name Type Range Description
inSurface Surface Input surface
inScanPath Path Path along which the scan is performed
inScanPathAlignment CoordinateSystem2D* Adjusts the scan path to the position of the inspected object
inScanWidth Integer 1 - Width of the scan field in pixels
inSurfaceInterpolation InterpolationMethod Interpolation method used for extraction of surface points
inEdgeScanParams EdgeScanParams3D Parameters controlling the surface edge extraction process
inEdgeSelection Selection If many edge points are possible, defines which one is selected
inLocalBlindness LocalBlindness* Defines conditions in which weaker edges can be detected in the vicinity of stronger edges
inMaxProfileGapWidth Integer* 0 - Maximal number of consecutive not existing profile points
outEdge SurfaceEdge1D? Found surface edge
outAlignedScanPath Path Path along which the scan is performed; in the image coordinate system
diagHeightProfile Profile Extracted surface height profile
diagResponseProfile Profile Profile of the edge (derivative) operator response


The operation scans the surface along inScanPath and locates the strongest edge perpendicular to the path. If the strongest edge is weaker than inEdgeScanParams.minMagnitude 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.

The operation is very similar to ScanSingleEdge from 1D Edge Detection category, but there are some substantial differences. One of these is the possibility of absence of information, because some surface points may not exist at all. To detect such edges, where solely change of existence matters, Valid/Invalid options of inEdgeScanParams.EdgeTransition can be used. Outside the surface domain (i.e. rectangle defined by input surface width, height, offsets and scales) there are no valid or invalid points, so no edge can be found in the direct vicinity of the domain border.

Because in the Valid/Invalid mode all edges have equal strength, if inEdgeSelection is set to Best, it will be implicitly substituted with First selection option.

Please note that when the input surface has unequal scales along X and Y axes and the scan path is not parallel to any of the axes, the results may be slightly less accurate because of uneven sampling along axes.


  • Connect an input surface to the inSurface input.
  • Create inScanPath which is more or less perpendicular to the edge you want to detect. It should be long enough to anticipate all possible edge locations.
  • Define inEdgeScanParams.EdgeTransition to detect a particular edge 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 inEdgeScanParams.SmoothingStdDev.
  • If no edge is found, try decreasing inEdgeScanParams.MinMagnitude. Verify this with the values on the diagResponseProfile output.
  • If consecutive edges are closer than 6 pixels apart, change inEdgeScanParams.ProfileInterpolation to Quadratic3.


For more information about local coordinate systems please refer to the following article.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of ScanEdges3D filter group.

See Also

  • ScanExactlyNEdges3D – Locates a specified number of the strongest changes of surface height along a given path.