boofcv.alg.feature.detect.line

Class GridRansacLineDetector<D extends boofcv.struct.image.ImageGray>

java.lang.Object

boofcv.alg.feature.detect.line.GridRansacLineDetector<D>

Direct Known Subclasses:

ImplGridRansacLineDetector_F32, ImplGridRansacLineDetector_S16

public abstract class GridRansacLineDetector<D extends boofcv.struct.image.ImageGray>
extends java.lang.Object

Line segment feature detector. The image is broken up into several regions of constant size. Inside each region pixels that have been flaged as belonging to edges are connected into lines using RANSAC or another ModelMatcher. The output is a list of detected lines in a grid of lists. This algorithm is inspired by [1], but has several differences in how the image is processed and how the output is produced.

The image is segmented into square regions of homogeneous size. Inside each region pixels which have been flagged as belonging to an edge are identified. Flagged edge pixels are referred to as "edgels" and have the image gradient at that point stored in their data structure. Gradient information is used to prune incompatible points from each other. RANSAC or similar algorithms are used to estimate and detect lines inside each region. Ones a line has been identified it is removed from the list of candidate points and more lines are searched for.

[1] J.C. Clarke, S. Carlsson, and A. Zisserman. "Detecting and tracking linear features efficiently" In. BMVC. British Machine Vision Association, 1996. 4,5,7.

Field Summary

Fields

Modifier and Type	Field and Description
protected org.ddogleg.struct.FastQueue<Edgel>	edgels
protected int	maxDetectLines
protected int	minInlierSize
protected int	regionSize

Constructor Summary

Constructors

Constructor and Description
GridRansacLineDetector(int regionSize, int maxDetectLines, org.ddogleg.fitting.modelset.ModelMatcher<georegression.struct.line.LinePolar2D_F32,Edgel> robustMatcher) Specifies major configuration parameters.

Method Summary

Modifier and Type	Method and Description
protected abstract void	detectEdgels(int index0, int x0, int y0, D derivX, D derivY, boofcv.struct.image.GrayU8 binaryEdges) Computes edgel information for pixels which have been flagged inside a region
MatrixOfList<georegression.struct.line.LineSegment2D_F32>	getFoundLines() Returns all the found line segments contained in a grid.
void	process(D derivX, D derivY, boofcv.struct.image.GrayU8 binaryEdges) Detects line segments through the image inside of grids.

Methods inherited from class java.lang.Object

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

Field Detail

regionSize

protected int regionSize

minInlierSize

protected int minInlierSize

edgels

protected org.ddogleg.struct.FastQueue<Edgel> edgels

maxDetectLines

protected int maxDetectLines

Constructor Detail

GridRansacLineDetector

public GridRansacLineDetector(int regionSize,
                              int maxDetectLines,
                              org.ddogleg.fitting.modelset.ModelMatcher<georegression.struct.line.LinePolar2D_F32,Edgel> robustMatcher)

Specifies major configuration parameters.

Parameters:

regionSize - Length of each side in a square region. Try 40.

maxDetectLines - Maximum number of lines which can be detected in a region. Try 10.

robustMatcher - Robust model matcher for line detection.

Method Detail

process

public void process(D derivX,
                    D derivY,
                    boofcv.struct.image.GrayU8 binaryEdges)

Detects line segments through the image inside of grids.

Parameters:

derivX - Image derivative along x-axis. Not modified.

derivY - Image derivative along x-axis. Not modified.

binaryEdges - True values indicate that a pixel is an edge pixel. Not modified.

getFoundLines

public MatrixOfList<georegression.struct.line.LineSegment2D_F32> getFoundLines()

Returns all the found line segments contained in a grid.

Returns:

Grid of detected lines.

detectEdgels

protected abstract void detectEdgels(int index0,
                                     int x0,
                                     int y0,
                                     D derivX,
                                     D derivY,
                                     boofcv.struct.image.GrayU8 binaryEdges)

Computes edgel information for pixels which have been flagged inside a region

Parameters:

index0 -

x0 - offset of region top left corner

y0 - offset of region top left corner

derivX - contains image derivative x-axis

derivY - contains image derivative y-axis

binaryEdges - Mark indicting which pixels are edges along a line