Package org.apache.sis.coverage.grid
Class GridDerivation
 Object

 GridDerivation

public class GridDerivation extends Object
Creates a new grid geometry derived from a base grid geometry with different extent or resolution.GridDerivation
are created by calls toGridGeometry.derive()
. Properties of the desired grid geometry can be specified by calls to the following methods, in that order (each method is optional):rounding(GridRoundingMode)
and/ormargin(int...)
in any orderresize(GridExtent, double...)
,subgrid(Envelope, double...)
orsubgrid(GridGeometry)
subsample(int...)
(if not set indirectly by above methods)slice(DirectPosition)
and/orsliceByRatio(double, int...)
build()
. Alternatively,getIntersection()
can be invoked if only theGridExtent
is desired instead than the fullGridGeometry
and no subsampling is applied.All methods in this class preserve the number of dimensions. For example the
slice(DirectPosition)
method sets the grid size to 1 in all dimensions specified by the slice point, but does not remove those dimensions from the grid geometry. For dimensionality reduction, seeGridGeometry.reduce(int...)
. Since:
 1.0
 See Also:
GridGeometry.derive()
,GridGeometry.reduce(int...)
Defined in the
sisfeature
module


Field Summary
Fields Modifier and Type Field Description protected GridGeometry
base
The base grid geometry from which to derive a new grid geometry.

Constructor Summary
Constructors Modifier Constructor Description protected
GridDerivation(GridGeometry base)
Creates a new builder for deriving a grid geometry from the specified base.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description GridGeometry
build()
Builds a grid geometry with the configuration specified by the other methods in thisGridDerivation
class.double
getGlobalScale()
Returns an estimation of the scale factor when converting subgrid coordinates tobase
grid coordinates.GridExtent
getIntersection()
Returns the extent of the modified grid geometry, ignoring subsamplings or changes in resolution.int[]
getSubsamplings()
Returns an estimation of the strides for accessing cells along each axis of base grid.GridDerivation
margin(int... cellCounts)
Specifies an amount of cells by which to expandGridExtent
after rounding.GridDerivation
resize(GridExtent extent, double... scales)
Requests a grid geometry where cell sizes have been scaled by the given factors, which result in a change of grid size.GridDerivation
rounding(GridRoundingMode mode)
Controls behavior of rounding from floating point values to integers.GridDerivation
slice(DirectPosition slicePoint)
Requests a grid geometry for a slice at the given "real world" position.GridDerivation
sliceByRatio(double sliceRatio, int... dimensionsToKeep)
Requests a grid geometry for a slice at the given relative position.GridDerivation
subgrid(GridGeometry gridOfInterest)
Adapts the base grid for the geographic area and resolution of the given grid geometry.GridDerivation
subgrid(Envelope areaOfInterest, double... resolution)
Requests a grid geometry over a subregion of the base grid geometry and optionally with subsampling.GridDerivation
subsample(int... subsamplings)
Applies a subsampling on the grid geometry to build.String
toString()
Returns a string representation of thisGridDerivation
for debugging purpose.



Field Detail

base
protected final GridGeometry base
The base grid geometry from which to derive a new grid geometry.


Constructor Detail

GridDerivation
protected GridDerivation(GridGeometry base)
Creates a new builder for deriving a grid geometry from the specified base. Parameters:
base
 the base to use as a template for deriving a new grid geometry. See Also:
GridGeometry.derive()


Method Detail

rounding
public GridDerivation rounding(GridRoundingMode mode)
Controls behavior of rounding from floating point values to integers. This setting modifies computations performed by the following methods (it has no effect on other methods in thisGridDerivation
class): If this method is never invoked, the default value isGridRoundingMode.NEAREST
. If this method is invoked too late, anIllegalStateException
is thrown. Parameters:
mode
 the new rounding mode. Returns:
this
for method call chaining. Throws:
IllegalStateException
 ifsubgrid(Envelope, double...)
orslice(DirectPosition)
has already been invoked.

margin
public GridDerivation margin(int... cellCounts)
Specifies an amount of cells by which to expandGridExtent
after rounding. This setting modifies computations performed by the following methods (it has no effect on other methods in thisGridDerivation
class): For each dimension i of the grid computed by above methods, the low grid coordinate is subtracted bycellCount[i]
and the high grid coordinate is increased bycellCount[i]
. The result is intersected with the extent of thebase
grid geometry given to the constructor.Use case: if the caller wants to apply bilinear interpolations in an image, (s)he will need 1 more pixel on each image border. If the caller wants to apply bicubic interpolations, (s)he will need 2 more pixels on each image border.If this method is never invoked, the default value is zero for all dimensions. If this method is invoked too late, anIllegalStateException
is thrown. If thecount
array length is shorter than the grid dimension, then zero is assumed for all missing dimensions. Parameters:
cellCounts
 number of cells by which to expand the grid extent. Returns:
this
for method call chaining. Throws:
IllegalArgumentException
 if a value is negative.IllegalStateException
 ifsubgrid(Envelope, double...)
orslice(DirectPosition)
has already been invoked.

resize
public GridDerivation resize(GridExtent extent, double... scales)
Requests a grid geometry where cell sizes have been scaled by the given factors, which result in a change of grid size. The new grid geometry is given a "grid to CRS" transform computed as the concatenation of given scale factors (applied on grid indices) followed by the grid to CRS transform of the grid geometry specified at construction time. The resulting grid extent can be specified explicitly (typically as an extent computed byGridExtent.resize(long...)
) or computed automatically by this method.Example: if the original grid geometry had an extent of [0 … 5] in x and [0 … 8] in y, then a call toresize(null, 0.1, 0.1)
will build a grid geometry with an extent of [0 … 50] in x and [0 … 80] in y. This new extent covers the same geographic area than the old extent but with pixels having a size of 0.1 times the old pixels size. The grid to CRS transform of the new grid geometry will be preconcatenated with scale factors of 0.1 in compensation for the shrink in pixels size.Notes:
 This method can be invoked only once.
 This method can not be used together with a
subgrid(…)
method.  If a nondefault rounding mode is desired, it should be specified before to invoke this method.
 This method does not reduce the number of dimensions of the grid geometry.
For dimensionality reduction, see
GridGeometry.reduce(int...)
.
subgrid(Envelope, double...)
working in grid coordinates space instead of CRS coordinates space. Parameters:
extent
 the grid extent to set as a result of the given scale, ornull
for computing it automatically. In nonnull, then this given extent is used asis without checking intersection with the base grid geometry.scales
 the scale factors to apply on grid indices. If the length of this array is smaller than the number of grid dimension, then a scale of 1 is assumed for all missing dimensions. Returns:
this
for method call chaining. Throws:
IllegalStateException
 if asubgrid(…)
orslice(…)
method has already been invoked. See Also:
subsample(int...)
,GridExtent.resize(long...)

subgrid
public GridDerivation subgrid(GridGeometry gridOfInterest)
Adapts the base grid for the geographic area and resolution of the given grid geometry. The new grid geometry will cover the spatiotemporal region given bygridOfInterest
envelope (coordinate operations are applied as needed if the Coordinate Reference Systems are not the same). The new grid geometry resolution will be integer multiples of thebase
grid geometry resolution.Usage: This method can be helpful for implementation ofThe following information are mandatory:GridCoverageResource.read(GridGeometry, int...)
. Example:class MyDataStorage extends GridCoverageResource { @Override public GridCoverage read(GridGeometry domain, int... range) throws DataStoreException { GridDerivation change = getGridGeometry().derive().subgrid(domain); GridExtent toRead = change.buildExtent(); int[] subsampling = change.getSubsamplings()); // Do reading here. } }
 Extent in
gridOfInterest
.  Grid to CRS conversion in
gridOfInterest
.  Grid to CRS conversion in
base
grid.
 Coordinate reference system in
gridOfInterest
.  Coordinate reference system in
base
grid.  Extent in
base
grid.
Notes:
 This method can be invoked only once.
 This method can not be used together with
subgrid(Envelope, double...)
orresize(GridExtent, double...)
.  If a nondefault rounding mode is desired, it should be specified before to invoke this method.
 This method does not reduce the number of dimensions of the grid geometry.
For dimensionality reduction, see
GridGeometry.reduce(int...)
.
 Parameters:
gridOfInterest
 the area of interest and desired resolution as a grid geometry. Returns:
this
for method call chaining. Throws:
DisjointExtentException
 if the given grid of interest does not intersect the grid extent.IncompleteGridGeometryException
 if a mandatory property of a grid geometry is absent.IllegalGridGeometryException
 if an error occurred while converting the envelope coordinates to grid coordinates.IllegalStateException
 if asubgrid(…)
orslice(…)
method has already been invoked. See Also:
getIntersection()
,getSubsamplings()
 Extent in

subgrid
public GridDerivation subgrid(Envelope areaOfInterest, double... resolution)
Requests a grid geometry over a subregion of the base grid geometry and optionally with subsampling. The given envelope does not need to be expressed in the same coordinate reference system (CRS) than the CRS of the base grid geometry; coordinate conversions or transformations will be applied as needed. That envelope CRS may have fewer dimensions than the base grid geometry CRS, in which case grid dimensions not mapped to envelope dimensions will be returned unchanged. The target resolution, if provided, shall be in same units and same order than the given envelope axes. If the length ofresolution
array is less than the number of dimensions ofareaOfInterest
, then no subsampling will be applied on the missing dimensions.Notes:
 This method can be invoked only once.
 This method can not be used together with
subgrid(GridGeometry)
orresize(GridExtent, double...)
.  If a nondefault rounding mode is desired, it should be specified before to invoke this method.
 This method does not reduce the number of dimensions of the grid geometry.
For dimensionality reduction, see
GridGeometry.reduce(int...)
.  If the given envelope is known to be expressed in the same CRS than the grid geometry,
then the CRS of the envelope
can be left unspecified (
null
). It may give a slight performance improvement by avoiding the check for coordinate transformation.
 Parameters:
areaOfInterest
 the desired spatiotemporal region in any CRS (transformations will be applied as needed), ornull
for not restricting the subgrid to a subarea.resolution
 the desired resolution in the same units and order than the axes of the given envelope, ornull
or an empty array if no subsampling is desired. The array length should be equal to theareaOfInterest
dimension, but this is not mandatory (zero or missing values mean no subsampling, extraneous values are ignored). Returns:
this
for method call chaining. Throws:
DisjointExtentException
 if the given area of interest does not intersect the grid extent.IncompleteGridGeometryException
 if the base grid geometry has no extent, no "grid to CRS" transform, or no CRS (unlessareaOfInterest
has no CRS neither, in which case the CRS are assumed the same).IllegalGridGeometryException
 if an error occurred while converting the envelope coordinates to grid coordinates.IllegalStateException
 if asubgrid(…)
orslice(…)
method has already been invoked. See Also:
getIntersection()
,getSubsamplings()

subsample
public GridDerivation subsample(int... subsamplings)
Applies a subsampling on the grid geometry to build. This method can be invoked as an alternative tosubgrid(…)
methods if only the resolution needs to be changed. The extent of the built grid geometry will be derived fromgetIntersection()
as below for each dimension i: The low is divided by
subsamplings[i]
, rounded toward zero.  The size is divided by
subsamplings[i]
, rounded toward zero.  The high is recomputed from above low and size.
 Parameters:
subsamplings
 the subsampling to apply on each grid dimension. All values shall be greater than zero. If the array length is shorter than the number of dimensions, missing values are assumed to be 1. Returns:
this
for method call chaining. Throws:
IllegalStateException
 if a subsampling has already been set, for example by a call tosubgrid(…)
. See Also:
subgrid(GridGeometry)
,getSubsamplings()
,GridExtent.subsample(int...)
 The low is divided by

slice
public GridDerivation slice(DirectPosition slicePoint)
Requests a grid geometry for a slice at the given "real world" position. The given position can be expressed in any coordinate reference system (CRS). The position should not define a coordinate for all dimensions, otherwise the slice would degenerate to a single point. Dimensions can be left unspecified either by assigning toslicePoint
a CRS without those dimensions, or by assigning the NaN value to some coordinates.Example: if the coordinate reference system of base grid geometry has (longitude, latitude, time) axes, then a (longitude, latitude) slice at time t can be created with one of the following two positions: A threedimensional position with (
Double.NaN
,Double.NaN
, t) coordinates.  A onedimensional position with (t) coordinate and the coordinate reference system set to the temporal component of the grid geometry CRS.
Notes:
 This method can be invoked after
subgrid(Envelope, double...)
, but not before.  If a nondefault rounding mode is desired, it should be specified before to invoke this method.
 This method does not reduce the number of dimensions of the grid geometry.
For dimensionality reduction, see
GridGeometry.reduce(int...)
.  If the given point is known to be expressed in the same CRS than the grid geometry,
then the CRS of the point
can be left unspecified (
null
). It may give a slight performance improvement by avoiding the check for coordinate transformation.
 Parameters:
slicePoint
 the coordinates where to get a slice. If no coordinate reference system is attached to it, we consider it's the same as base grid geometry. Returns:
this
for method call chaining. Throws:
IncompleteGridGeometryException
 if the base grid geometry has no extent, no "grid to CRS" transform, or no CRS (unlessslicePoint
has no CRS neither, in which case the CRS are assumed the same).IllegalGridGeometryException
 if an error occurred while converting the point coordinates to grid coordinates.RuntimeException
 if the given point is outside the grid extent.
 A threedimensional position with (

sliceByRatio
public GridDerivation sliceByRatio(double sliceRatio, int... dimensionsToKeep)
Requests a grid geometry for a slice at the given relative position. The relative position is specified by a ratio between 0 and 1 where 0 maps to low grid coordinates, 1 maps to high grid coordinates and 0.5 maps to the median position. The slicing is applied on all dimensions except the specified dimensions to keep.Example: given a ndimensional cube, the following call creates a slice of the two first dimensions (numbered 0 and 1, typically the dimensions of x and y axes) located at the center (ratio 0.5) of all other dimensions (typically z and/or t axes):gridGeometry.derive().sliceByRatio(0.5, 0, 1).build();
 Parameters:
sliceRatio
 the ratio to apply on all grid dimensions except the ones to keep.dimensionsToKeep
 the grid dimension to keep unchanged. Returns:
this
for method call chaining. Throws:
IncompleteGridGeometryException
 if the base grid geometry has no extent.IndexOutOfBoundsException
 if adimensionsToKeep
value is out of bounds.

build
public GridGeometry build()
Builds a grid geometry with the configuration specified by the other methods in thisGridDerivation
class. Returns:
 the modified grid geometry. May be the
base
grid geometry if no change apply.  See Also:
getIntersection()

getIntersection
public GridExtent getIntersection()
Returns the extent of the modified grid geometry, ignoring subsamplings or changes in resolution. This is the intersection of thebase
grid geometry with the (grid or geospatial) envelope given to asubgrid(…)
method, expanded by the specified margin (if any) and potentially with some grid sizes set to 1 if aslice(…)
method has been invoked. The returned extent is in units of thebase
grid cells, i.e. subsamplings are ignored. Returns:
 intersection of grid geometry extents in units of
base
grid cells.

getSubsamplings
public int[] getSubsamplings()
Returns an estimation of the strides for accessing cells along each axis of base grid. Ifsubsample(int...)
has been invoked, then this method returns the argument values given to that method. Otherwise if asubgrid(…)
method has been invoked, then this method computes the subsamplings as below: Given a conversion fromgridOfInterest
grid coordinates (x, y, z) tobase
grid coordinates (x′, y′, z′) defined as below (generalize to as many dimensions as needed): x′ = s₀⋅x
 y′ = s₁⋅y
 z′ = s₂⋅z
gridOfInterest
grid coordinates with a stride Δx=1 corresponds approximately to an iteration inbase
grid coordinates with a stride of Δx′=s₀, a stride Δy=1 corresponds approximately to a stride Δy′=s₁, etc. If the conversion changes grid axis order, then the order of elements in the returned array is the order of axes in thebase
grid. Returns:
 an estimation of the strides for accessing cells along each axis of
base
grid.  See Also:
subgrid(GridGeometry)
,subgrid(Envelope, double...)
,subsample(int...)

getGlobalScale
public double getGlobalScale()
Returns an estimation of the scale factor when converting subgrid coordinates tobase
grid coordinates. This is for information purpose only since this method combines potentially different scale factors for all dimensions. Returns:
 an estimation of the scale factor for all dimensions.
 See Also:
subgrid(GridGeometry)
,subgrid(Envelope, double...)

toString
public String toString()
Returns a string representation of thisGridDerivation
for debugging purpose. The returned string is implementation dependent and may change in any future version.

