edu.umich.eecs.april.tag

Class TagDetection

java.lang.Object

edu.umich.eecs.april.tag.TagDetection

public class TagDetection
extends java.lang.Object

Detect a tag.

Field Summary

Fields

Modifier and Type	Field and Description
long	code Matched code.
double[]	cxy Center of tag in pixel coordinates.
boolean	good Is the detection good enough?
int	hammingDistance The hamming distance between the detected code and the true code.
double[][]	homography A 3x3 homography that computes pixel coordinates from tag-relative coordinates.
double[]	hxy The homography is relative to image center, whose coordinates are below.
int	id What was the ID of the detected tag?
long	obsCode Observed code.
double	observedPerimeter Measured in pixels, how long was the observed perimeter (i.e., excluding inferred perimeter which is used to connect incomplete quads).
double[][]	p Position (in fractional pixel coordinates) of the detection.
int	rotation How many 90 degree rotations were required to align the code.

Constructor Summary

Constructors

Constructor and Description
TagDetection()

Method Summary

Modifier and Type	Method and Description
double[]	interpolate(double x, double y) Interpolate point given (x,y) is in tag coordinate space from (-1,-1) to (1,1).
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

good

public boolean good

Is the detection good enough?

obsCode

public long obsCode

Observed code.

code

public long code

Matched code.

id

public int id

What was the ID of the detected tag?

hammingDistance

public int hammingDistance

The hamming distance between the detected code and the true code.

rotation

public int rotation

How many 90 degree rotations were required to align the code.

p

public double[][] p

Position (in fractional pixel coordinates) of the detection. The points travel around counter clockwise around the target, always starting from the same corner of the tag. Dimensions [4][2].

cxy

public double[] cxy

Center of tag in pixel coordinates.

observedPerimeter

public double observedPerimeter

Measured in pixels, how long was the observed perimeter (i.e., excluding inferred perimeter which is used to connect incomplete quads).

homography

public double[][] homography

A 3x3 homography that computes pixel coordinates from tag-relative coordinates. Both the input and output coordinates are 2D homogenous vectors, with y = Hx. y are pixel coordinates, x are tag-relative coordinates. Tag coordinates span from (-1,-1) to (1,1). The orientation of the homography reflects the orientation of the target.

hxy

public double[] hxy

The homography is relative to image center, whose coordinates are below.

Constructor Detail

TagDetection

public TagDetection()

Method Detail

interpolate

public double[] interpolate(double x,
                            double y)

Interpolate point given (x,y) is in tag coordinate space from (-1,-1) to (1,1).

Parameters:

x - The x value

y - The y value

Returns:

The interpolated point.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object