org.openimaj.math.geometry.transforms.estimation.sampling

Class BucketingSampler2d

java.lang.Object

org.openimaj.math.geometry.transforms.estimation.sampling.BucketingSampler2d

All Implemented Interfaces:

CollectionSampler<IndependentPair<Point2d,Point2d>>

@Reference(type=Article,
           author={"Zhengyou Zhang","Rachid Deriche","Olivier Faugeras","Quang-Tuan Luong"},
           title="A robust technique for matching two uncalibrated images through the recovery of the unknown epipolar geometry ",
           year="1995",
           journal="Artificial Intelligence ",
           pages={"87 "," 119"},
           url="http://www.sciencedirect.com/science/article/pii/0004370295000224",
           note="Special Volume on Computer Vision ",
           number="1--2",
           volume="78",
           customData={"issn","0004-3702","doi","http://dx.doi.org/10.1016/0004-3702(95)00022-4","keywords","Correlation "})
public class BucketingSampler2d
extends Object
implements CollectionSampler<IndependentPair<Point2d,Point2d>>

Implementation of the bucketing sampling strategy proposed by Zhang et al to try and ensure a good spatial distribution of point-pairs for estimation of geometric transforms and the fundamental matrix.

Works by splitting the space of first image points into a number of buckets. When selecting the sample, a bucket is chosen at random, with the probability of the bucket being picked weighted towards buckets with more points. Then a point pair is picked using a uniform random from within the bucket. Additionally, the algorithm attempts to pick unique buckets for each point by attempting to discount previously selected buckets if possible.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_N_BUCKETS_PER_DIM Default number of buckets per dimension
static int	NUM_TRIALS Maximum allowed number of trials in picking a bucket that has not been previously picked.

Constructor Summary

Constructors

Constructor and Description
BucketingSampler2d() Construct the sampler with the default number of buckets in the x and y dimensions (8).
BucketingSampler2d(int nBucketsX, int nBucketsY) Construct the sampler with the given number of buckets in each dimension.

Method Summary

Modifier and Type	Method and Description
List<IndependentPair<Point2d,Point2d>>	sample(int nItems)
void	setCollection(Collection<? extends IndependentPair<Point2d,Point2d>> collection)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_N_BUCKETS_PER_DIM

public static final int DEFAULT_N_BUCKETS_PER_DIM

Default number of buckets per dimension

See Also:

Constant Field Values

NUM_TRIALS

public static int NUM_TRIALS

Maximum allowed number of trials in picking a bucket that has not been previously picked.

Constructor Detail

BucketingSampler2d

public BucketingSampler2d()

Construct the sampler with the default number of buckets in the x and y dimensions (8).

BucketingSampler2d

public BucketingSampler2d(int nBucketsX,
                          int nBucketsY)

Construct the sampler with the given number of buckets in each dimension.

Parameters:

nBucketsX - number of buckets in the x dimension

nBucketsY - number of buckets in the y dimension

Method Detail

setCollection

public void setCollection(Collection<? extends IndependentPair<Point2d,Point2d>> collection)

Specified by:

setCollection in interface CollectionSampler<IndependentPair<Point2d,Point2d>>

sample

public List<IndependentPair<Point2d,Point2d>> sample(int nItems)

Specified by:

sample in interface CollectionSampler<IndependentPair<Point2d,Point2d>>