Back to FabImage Library website

You are here: Start » Function Reference » Path » Path Spatial Transforms » FitPathToPath

FitPathToPath


Header: FIL.h
Namespace: fil
Module: FoundationPro

Rotates and shifts a path to minimize average distance between its points and a reference path.

Syntax

C++
C#
 
void fil::FitPathToPath
(
	const fil::Path& inPath,
	const fil::Path& inReferencePath,
	fil::PathOrientationAlignment::Type inPathOrientationAlignment,
	const int inIterations,
	const float inFirstShift,
	const float inFirstRotation,
	fil::Path& outPath,
	fil::CoordinateSystem2D& outAlignment,
	float& outPathDistance
)

Parameters

Name Type Range Default Description
Input value inPath const Path& Path to be aligned
Input value inReferencePath const Path& Path to align to
Input value inPathOrientationAlignment PathOrientationAlignment::Type EllipticAxes Determines how to align paths orientation before the main algorithm
Input value inIterations const int 1 - 5 Number of algorithm steps
Input value inFirstShift const float 10.0f Magnitude of possible shift at the first step in pixels
Input value inFirstRotation const float 10.0f Magnitude of possible rotation at the first step in degrees
Output value outPath Path& Aligned path
Output value outAlignment CoordinateSystem2D& The coordinate system that geometrical objects defined in the context of the path should be aligned to
Output value outPathDistance float& Average distance of characteristic points of the input path from the reference path

Description

The operations repeatedly performs shifts and rotations on the inPath minimizing the average distance between its characteristic points and inReferencePath.

Initially the inPath is shifted so that its mass center is equals the mass center of inReferencePath. Then the alignment is performed in inIterations steps. At each step the algorithm considers:

  1. Shifts of the processed path in four major directions by ShiftMagnitude pixels
  2. Rotations of the processed path in clockwise and counter-clockwise direction by RotationMagnitude degrees

At each substep the operation performs shift or rotation that produces the best distance minimization results. The initial value of ShiftMagnitude is inFirstShift and at each step it is divided by 2. Analogically the initial value of RotationMagnitude is inFirstRotation and at each step it is divided by 2.

Examples

FitPathToPath run on the sample paths with inIterations = 5, inFirstShift = 10, inFirstRotation = 10. The inReferencePath plotted in grey, the inPath/outPath in black.

Errors

List of possible exceptions:

Error type Description
DomainError Empty path on input in FitPathToPath.