Package boofcv.alg.geo.triangulate

Class PixelDepthLinearMetric

java.lang.Object

boofcv.alg.geo.triangulate.PixelDepthLinearMetric

public class PixelDepthLinearMetric
extends Object

Computes the depth (value of z-axis in frame A) for a single point feature given N observations and N-1 rigid camera transforms. The estimate will be optimal an algebraic sense, but not in a Euclidean sense. Two variants are provided in this class, for 2 views and N>1 views. All pixel coordinates are in calibrated units.

This linear estimation of pixel depth is done using the following equation:
λ₁*hat(x₂)*R*x₁ + hat(x₂)*T = 0
where λ₁ is the pixel depth in the first image, x is an observation in calibrated homogeneous coordinates, and (R,T) is a rigid body transformation. Modified implementation of the algorithm described in [1].

To go from pixel depth to a 3D coordinate simply multiply the observation in calibrated (z=1) homogeneous coordinates by the returned depth.

[1] Page 267 in Y. Ma, S. Soatto, J. Kosecka, and S. S. Sastry, "An Invitation to 3-D Vision" Springer-Verlad, 2004

Constructor Summary

Constructors

Constructor	Description
PixelDepthLinearMetric()

Method Summary

Modifier and Type	Method	Description
double	depth2View(Point2D_F64 a, Point2D_F64 b, Se3_F64 fromAtoB)	Computes pixel depth in image 'a' from two observations.
double	depthNView(List<Point2D_F64> obs, List<Se3_F64> motion)	Computes the pixel depth from N views of the same object.

Methods inherited from class java.lang.Object

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

Constructor Details

PixelDepthLinearMetric

public PixelDepthLinearMetric()

Method Details

depthNView

public double depthNView(List<Point2D_F64> obs,
 List<Se3_F64> motion)

Computes the pixel depth from N views of the same object. Pixel depth in the first frame.

Parameters:

obs - List of observations on a single feature in normalized coordinates

motion - List of camera motions. Each index 'i' is the motion from view 0 to view i+1.

Returns:

depth of the pixels

depth2View

public double depth2View(Point2D_F64 a,
 Point2D_F64 b,
 Se3_F64 fromAtoB)

Computes pixel depth in image 'a' from two observations.

Parameters:

a - Observation in first frame. In calibrated coordinates. Not modified.

b - Observation in second frame. In calibrated coordinates. Not modified.

fromAtoB - Transform from frame a to frame b.

Returns:

Pixel depth in first frame. In same units as T inside of fromAtoB.