AprilTags::Edge Class Reference

Represents an edge between adjacent pixels in the image. More...

#include <Edge.h>

Detailed Description

Represents an edge between adjacent pixels in the image.

The edge is encoded by the indices of the two pixels. Edge cost is proportional to the difference in local orientations.

Definition at line 20 of file Edge.h.

List of all members.

Public Member Functions
	Edge ()
	Constructor.
bool	operator< (const Edge &other) const
	Compare edges based on cost.
Static Public Member Functions
static short int	edgeCost (float theta0, float theta1, float mag1)
	Cost of an edge between two adjacent pixels; -1 if no edge here.
static void	calcEdges (float theta0, int x, int y, const FloatImage &theta, const FloatImage &mag, std::vector< Edge > &edges, size_t &nEdges)
	Calculates and inserts up to four edges into 'edges', a vector of Edges.
static void	mergeEdges (std::vector< Edge > &edges, UnionFindSimple &uf, float tmin[], float tmax[], float mmin[], float mmax[])
	Process edges in order of increasing cost, merging clusters if we can do so without exceeding the thetaThresh.
Public Attributes
int	pixelIdxA
int	pixelIdxB
short int	cost
Static Public Attributes
static float const	minMag = 0.004f
	minimum intensity gradient for an edge to be recognized
static float const	maxEdgeCost = 30.f * float(M_PI) / 180.f
	30 degrees = maximum acceptable difference in local orientations
static int const	WEIGHT_SCALE = 100
static float const	thetaThresh = 100
	theta threshold for merging edges
static float const	magThresh = 1200
	magnitude threshold for merging edges

Constructor & Destructor Documentation

AprilTags::Edge::Edge ( )

Constructor.

Definition at line 33 of file Edge.h.

Member Function Documentation

void AprilTags::Edge::calcEdges	(	float	theta0,
		int	x,
		int	y,
		const FloatImage &	theta,
		const FloatImage &	mag,
		std::vector< Edge > &	edges,
		size_t &	nEdges
	)			`[static]`

Calculates and inserts up to four edges into 'edges', a vector of Edges.

Definition at line 26 of file Edge.cc.

Referenced by AprilTags::TagDetector::extractTags().

short int AprilTags::Edge::edgeCost	(	float	theta0,
		float	theta1,
		float	mag1
	)			`[static]`

Cost of an edge between two adjacent pixels; -1 if no edge here.

An edge exists between adjacent pixels if the magnitude of the intensity gradient at both pixels is above threshold. The edge cost is proportional to the difference in the local orientation at the two pixels. Lower cost is better. A cost of -1 means there is no edge here (intensity gradien fell below threshold).

Definition at line 14 of file Edge.cc.

Referenced by calcEdges().