org.geotools.process.raster

Class MarchingSquaresVectorizer

Object

MarchingSquaresVectorizer

public final class MarchingSquaresVectorizer
extends Object

Algorithm computing the image footprint. Some optimizations are made. When running along the image perimeter, whenever a closed polygon is found, the inner area is filled to make sure we won't analyze that.

It can deal with GridCoverage2D instances, returning footprint in real world coordinates, as well as with RenderedImage instances, returning footprint in raster space coordinates

Author:

Daniele Romagnoli, GeoSolutions SAS, Simone Giannecchini, GeoSolutions SAS, Andrea Aime, GeoSolutions SAS

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MarchingSquaresVectorizer.FootprintCoordinates
static class	MarchingSquaresVectorizer.ImageAnalysisResultThdLocal
static class	MarchingSquaresVectorizer.ImageLoadingType

Field Summary

Fields

Modifier and Type	Field and Description
static List<Range<Integer>>	DEFAULT_RANGES
static double	DEFAULT_SIMPLIFIER_FACTOR
static double	DEFAULT_THRESHOLD_AREA

Constructor Summary

Constructors

Constructor and Description
MarchingSquaresVectorizer()
MarchingSquaresVectorizer(GridCoverage2D inGeodata, RenderingHints hints, double thresholdArea, double simplifierFactor, MarchingSquaresVectorizer.ImageLoadingType imageLoadingType, List<Range<Integer>> exclusionLuminanceRanges) Main Constructor using GridCoverage2D as input.
MarchingSquaresVectorizer(RenderedImage ri, RenderingHints hints, double thresholdArea, MarchingSquaresVectorizer.ImageLoadingType imageLoadingType, List<Range<Integer>> exclusionLuminanceRanges) Main Constructor using RenderedImage as input.

Method Summary

Modifier and Type	Method and Description
static boolean	areEqual(double value, double pValue) Simple check returning where two double values are equal
static Polygon	createSimplePolygon(Coordinate[] coords) Create a simple polygon (no holes).
void	dispose()
Geometry	getFootprint() Return the precise footprint
MarchingSquaresVectorizer.ImageLoadingType	getImageLoadingType()
double	getPolygonArea() Return the area of the simplified footprint after computation
static double	getPolygonArea(int[] x, int[] y, int N) Calculates the area of a polygon from its vertices.
static double	getPolygonArea(List<Coordinate> coordinateList) Calculates the area of a polygon from the coordinates.
ROIShape	getRoiShape() Return the ROIShape version of the footprint after computation
Geometry	getSimplifiedFootprint() Return the simplified footprint
void	process() Executes the MarchingSquares algorithm to find the footprint.
void	setComputeSimplifiedFootprint(boolean computeSimplifiedFootprint) When set to true, a simplified version of the footprint will be returned too
void	setForceValid(boolean forceValid) When set to true (the default) will perform extra checks on the output polygons to make sure they are valid geometries
void	setImageLoadingType(MarchingSquaresVectorizer.ImageLoadingType imageLoadingType) Specifies which type of imageLoading (MarchingSquaresVectorizer.ImageLoadingType) to be used, MarchingSquaresVectorizer.ImageLoadingType.DEFERRED vs MarchingSquaresVectorizer.ImageLoadingType.IMMEDIATE
void	setRemoveCollinear(boolean removeCollinear) When set to true (the default) will perform collinear vertices removal

Methods inherited from class Object

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

Field Detail

DEFAULT_RANGES

public static final List<Range<Integer>> DEFAULT_RANGES

DEFAULT_SIMPLIFIER_FACTOR

public static final double DEFAULT_SIMPLIFIER_FACTOR

See Also:

Constant Field Values

DEFAULT_THRESHOLD_AREA

public static final double DEFAULT_THRESHOLD_AREA

See Also:

Constant Field Values

Constructor Detail

MarchingSquaresVectorizer

public MarchingSquaresVectorizer(GridCoverage2D inGeodata,
                                 RenderingHints hints,
                                 double thresholdArea,
                                 double simplifierFactor,
                                 MarchingSquaresVectorizer.ImageLoadingType imageLoadingType,
                                 List<Range<Integer>> exclusionLuminanceRanges)

Main Constructor using GridCoverage2D as input.

Parameters:

inGeodata - the input GridCoverage2D

hints - hints to be used by inner processing, it usually contains tile caches, schedulers

thresholdArea - the minimum area required by a polygon to be included in the result

simplifierFactor - the simplifier factor to be applied to compute the simplified version of the biggest polygon.

imageLoadingType - the type of imageLoading (DEFERRED vs IMMEDIATE).

exclusionLuminanceRanges - the ranges of luminance values to be excluded by the computation.

MarchingSquaresVectorizer

public MarchingSquaresVectorizer(RenderedImage ri,
                                 RenderingHints hints,
                                 double thresholdArea,
                                 MarchingSquaresVectorizer.ImageLoadingType imageLoadingType,
                                 List<Range<Integer>> exclusionLuminanceRanges)

Main Constructor using RenderedImage as input. Returned footprint coordinates will be in raster space.

Parameters:

ri - the input RenderedImage

hints - hints to be used by inner processing, it usually contains tile caches, schedulers

thresholdArea - the minimum area required by a polygon to be included in the result

imageLoadingType - the type of imageLoading (DEFERRED vs IMMEDIATE).

exclusionLuminanceRanges - the range of luminance values to be excluded by the computation.

MarchingSquaresVectorizer

public MarchingSquaresVectorizer()

Method Detail

getRoiShape

public ROIShape getRoiShape()

Return the ROIShape version of the footprint after computation

getPolygonArea

public double getPolygonArea()

Return the area of the simplified footprint after computation

getSimplifiedFootprint

public Geometry getSimplifiedFootprint()

Return the simplified footprint

getFootprint

public Geometry getFootprint()

Return the precise footprint

setRemoveCollinear

public void setRemoveCollinear(boolean removeCollinear)

When set to true (the default) will perform collinear vertices removal

setForceValid

public void setForceValid(boolean forceValid)

When set to true (the default) will perform extra checks on the output polygons to make sure they are valid geometries

setComputeSimplifiedFootprint

public void setComputeSimplifiedFootprint(boolean computeSimplifiedFootprint)

When set to true, a simplified version of the footprint will be returned too

setImageLoadingType

public void setImageLoadingType(MarchingSquaresVectorizer.ImageLoadingType imageLoadingType)

Specifies which type of imageLoading (MarchingSquaresVectorizer.ImageLoadingType) to be used, MarchingSquaresVectorizer.ImageLoadingType.DEFERRED vs MarchingSquaresVectorizer.ImageLoadingType.IMMEDIATE

getImageLoadingType

public MarchingSquaresVectorizer.ImageLoadingType getImageLoadingType()

process

public void process()
             throws Exception

Executes the MarchingSquares algorithm to find the footprint.

Throws:

Exception

areEqual

public static final boolean areEqual(double value,
                                     double pValue)

Simple check returning where two double values are equal

dispose

public void dispose()

getPolygonArea

public static double getPolygonArea(List<Coordinate> coordinateList)

Calculates the area of a polygon from the coordinates.

Returns:

the area of the polygon.

getPolygonArea

public static double getPolygonArea(int[] x,
                                    int[] y,
                                    int N)

Calculates the area of a polygon from its vertices.

Parameters:

x - the array of x coordinates.

y - the array of y coordinates.

N - the number of sides of the polygon.

Returns:

the area of the polygon.

createSimplePolygon

public static Polygon createSimplePolygon(Coordinate[] coords)

Create a simple polygon (no holes).

Parameters:

coords - the coords of the polygon.

Returns:

the Polygon.