Class LocalizationGrid
 Object

 LocalizationGrid

 All Implemented Interfaces:
Serializable
 Direct Known Subclasses:
NADConGridShift
public class LocalizationGrid extends Object implements Serializable
A factory forMathTransform2D
backed by a grid of localization. A grid of localization is a twodimensional array of coordinate points. The grid size iswidth
×height
. Input coordinates are (i,j) index in the grid, where i must be in the range[0..width1]
and j in the range[0..height1]
inclusive. Output coordinates are the values stored in the grid of localization at the specified index.The
LocalizationGrid
class is usefull when the "grid to coordinate system" transform for a coverage is not some kind of global mathematical relationship like an affine transform. Instead, the "real world" coordinates are explicitly specified for each pixels. If the real world coordinates are know only for some pixels at a fixed interval, then a transformation can be constructed by the concatenation of an affine transform with a grid of localization.After a
LocalizationGrid
object has been fully constructed (i.e. real world coordinates have been specified for all grid cells), a transformation from grid coordinates to "real world" coordinates can be obtained with thegetMathTransform()
method. If this transformation is close enough to an affine transform, then an instance ofAffineTransform
is returned. Otherwise, a transform backed by the localization grid is returned.The example below goes through the steps of constructing a coordinate reference system for a grid coverage from its grid of localization. This example assumes that the "real world" coordinates are longitudes and latitudes on the WGS84 ellipsoid.
// // Constructs a localization grid of size 10×10. // LocalizationGrid grid = new LocalizationGrid(10,10); for (int j=0; j<10; j++) { for (int i=0; i<10; i++) { double x = ...; // Set longitude here double y = ...; // Set latitude here grid.setLocalizationPoint(i,j,x,y); } } // // Constructs the grid coordinate reference system. degree is the polynomial // degree (e.g. 2) for a math transform that approximately map the grid of localization. // For a more accurate (but not always better) math transform backed by the whole grid, // invokes getMathTransform() instead, or use the special value of 0 for the degree // argument. // MathTransform2D realToGrid = grid.getPolynomialTransform(degree).inverse(); CoordinateReferenceSystem realCRS = DefaultGeographicCRS.WGS84; CoordinateReferenceSystem gridCRS = new DefaultDerivedCRS("The grid CRS", new DefaultOperationMethod(realToGrid), realCRS, // The target ("real world") CRS realToGrid, // How the grid CRS relates to the "real world" CRS DefaultCartesianCS.GRID); // // Constructs the grid coverage using the grid coordinate system (not the "real world" // one). It is usefull to display the coverage in its native CRS before we resample it. // Note that if the grid of localization does not define the geographic location for // all pixels, then we need to specify some affine transform in place of the call to // IdentityTransform. For example if the grid of localization defines the location of // 1 pixel, then skip 3, then defines the location of 1 pixel, etc., then the affine // transform should be AffineTransform.getScaleInstance(0.25, 0.25). // WritableRaster raster = RasterFactory.createBandedRaster(DataBuffer.TYPE_FLOAT, width, height, 1, null); for (int y=0; y
some_value); } } GridCoverageFactory factory = FactoryFinder.getGridCoverageFactory(null); GridCoverage coverage = factory.create("My grayscale coverage", raster, gridCRS, IdentityTransform.create(2), null, null, null, null, null); coverage.show(); // // Projects the coverage from its current 'gridCS' to the 'realCS'. If the grid of // localization was built from the orbit of some satellite, then the projected // coverage will tpypically have a curved aspect. // coverage = (Coverage2D) Operations.DEFAULT.resample(coverage, realCRS); coverage.show();  Since:
 2.4
 Author:
 Remi Eve, Martin Desruisseaux (IRD), Alessio Fabiani
 See Also:
DerivedCRS
, Serialized Form


Constructor Summary
Constructors Constructor Description LocalizationGrid(int width, int height)
Constructs an initially empty localization grid.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description AffineTransform
getAffineTransform()
Returns an affine transform for the whole grid.Point2D
getLocalizationPoint(Point source)
Returns the "real world" coordinates for the specified grid coordinates.MathTransform2D
getMathTransform()
Returns a math transform from grid to "real world" coordinates.MathTransform2D
getPolynomialTransform(int degree)
Returns a math transform from grid to "real world" coordinates using a polynomial fitting of the specified degree.Dimension
getSize()
Returns the grid size.boolean
isMonotonic(boolean strict)
Returnstrue
if all coordinates in this grid are increasing or decreasing.boolean
isNaN()
Returnstrue
if this localization grid contains at least oneNaN
value.void
removeSingularities()
Makes sure that the grid doesn't contains identical consecutive ordinates.void
setLocalizationPoint(int sourceX, int sourceY, double targetX, double targetY)
Set a point in this localization grid.void
setLocalizationPoint(Point source, Point2D target)
Set a point in this localization grid.void
transform(AffineTransform transform, Rectangle region)
Apply a transformation to every "real world" coordinate points in a subregion of this grid.



Method Detail

getSize
public Dimension getSize()
Returns the grid size. Grid coordinates are always in the rangex_{input} = [0..width1]
andy_{input} = [0..height1]
inclusive.

getLocalizationPoint
public Point2D getLocalizationPoint(Point source)
Returns the "real world" coordinates for the specified grid coordinates. Grid coordinates must be integers inside this grid's range. For general transformations involving noninteger grid coordinates and/or coordinates outside this grid's range, usegetMathTransform()
instead. Parameters:
source
 The point in grid coordinates. Returns:
 target The corresponding point in "real world" coordinates.
 Throws:
IndexOutOfBoundsException
 If the source point is not in this grid's range.

setLocalizationPoint
public void setLocalizationPoint(Point source, Point2D target)
Set a point in this localization grid. Parameters:
source
 The point in grid coordinates.target
 The corresponding point in "real world" coordinates. Throws:
IndexOutOfBoundsException
 If the source point is not in this grid's range.

setLocalizationPoint
public void setLocalizationPoint(int sourceX, int sourceY, double targetX, double targetY)
Set a point in this localization grid. Parameters:
sourceX
 x coordinates in grid coordinates, in the range[0..width1]
inclusive.sourceY
 y coordinates in grid coordinates. in the range[0..height1]
inclusive.targetX
 x coordinates in "real world" coordinates.targetY
 y coordinates in "real world" coordinates. Throws:
IndexOutOfBoundsException
 If the source coordinates is not in this grid's range.

transform
public void transform(AffineTransform transform, Rectangle region)
Apply a transformation to every "real world" coordinate points in a subregion of this grid. Parameters:
transform
 The transform to apply.region
 The bounding rectangle (in grid coordinate) for region where to apply the transform, ornull
to transform the whole grid.

isNaN
public boolean isNaN()
Returnstrue
if this localization grid contains at least oneNaN
value.

isMonotonic
public boolean isMonotonic(boolean strict)
Returnstrue
if all coordinates in this grid are increasing or decreasing. More specifically, returnstrue
if the following conditions are meets: Coordinates in a row must be increasing or decreasing. If
strict
istrue
, then coordinates must be strictly increasing or decreasing (i.e. equals value are not accepted).NaN
values are always ignored.  Coordinates in all rows must be increasing, or coordinates in all rows must be decreasing.
 Idem for columns (Coordinates in a columns must be increasing or decreasing, etc.).
 Parameters:
strict
true
to require strictly increasing or decreasing order, orfalse
to accept values that are equals. Returns:
true
if coordinates are increasing or decreasing in the same direction for all rows and columns.
 Coordinates in a row must be increasing or decreasing. If

removeSingularities
public void removeSingularities()
Makes sure that the grid doesn't contains identical consecutive ordinates. If many consecutives ordinates are found to be identical in a row or in a column, then the first one is left inchanged and the other ones are linearly interpolated.

getAffineTransform
public AffineTransform getAffineTransform()
Returns an affine transform for the whole grid. This transform is only an approximation for this localization grid. It is fitted (like "curve fitting") to grid data using the "least squares" method. Returns:
 A global affine transform as an approximation for the whole localization grid.

getPolynomialTransform
public MathTransform2D getPolynomialTransform(int degree)
Returns a math transform from grid to "real world" coordinates using a polynomial fitting of the specified degree. By convention, adegree
of 0 will returns the math transform backed by the whole grid. Greater values will use a fitted polynomial (affine transform for degree 1, quadratic transform for degree 2, cubic transform for degree 3, etc.). Parameters:
degree
 The polynomial degree for the fitting, or 0 for a transform backed by the whole grid.

getMathTransform
public final MathTransform2D getMathTransform()
Returns a math transform from grid to "real world" coordinates. The math transform is backed by the full grid of localization. In terms of JAI's image warp operations, this math transform is backed by aWarpGrid
while the previous methods return math transforms backed byWarpPolynomial
.

