Package org.apache.sis.coverage.grid

Class GridEvaluator

Object
GridEvaluator
All Implemented Interfaces:
Function<Direct­Position,double[]>, Banded­Coverage​.Evaluator
public class GridEvaluator extends Object implements BandedCoverage.Evaluator
Computes or interpolates values of sample dimensions at given positions. Values are computed by calls to apply(Direct­Position) and are returned as double[].

Multi-threading

Evaluators are not thread-safe. An instance of Grid­Evaluator should be created for each thread that need to compute sample values.

Limitations

Current implementation performs nearest-neighbor sampling only. A future version will provide interpolations.
Since:
1.1
See Also:

Defined in the sis-feature module

  • Constructor Details

  • Method Details

    • getCoverage

      public GridCoverage getCoverage()
      Returns the coverage from which this evaluator is fetching sample values.
      Specified by:
      get­Coverage in interface Banded­Coverage​.Evaluator
      Returns:
      the source of sample values for this evaluator.

    • isWraparoundEnabled

      public boolean isWraparoundEnabled()
      Returns true if this evaluator is allowed to wraparound coordinates that are outside the grid. The initial value is false. This method may continue to return false even after a call to set­Wraparound­Enabled(true) if no wraparound axis has been found in the coverage CRS.
      Returns:
      true if this evaluator may wraparound coordinates that are outside the grid.
      Since:
      1.2

    • setWraparoundEnabled

      public void setWraparoundEnabled(boolean allow)
      Specifies whether this evaluator is allowed to wraparound coordinates that are outside the grid. If true and if a given coordinate is outside the grid, then this evaluator may translate the point along a wraparound axis in an attempt to get the point inside the grid. For example if the coverage CRS has a longitude axis, then the evaluator may translate the longitude value by a multiple of 360°.
      Parameters:
      allow - whether to allow wraparound of coordinates that are outside the grid.
      Since:
      1.2

    • isNullIfOutside

      public boolean isNullIfOutside()
      Returns whether to return null instead of throwing an exception if a point is outside coverage bounds. The default value is false, which means that the default apply(Direct­Position) behavior is to throw Point­Outside­Coverage­Exception for points outside bounds.
      Specified by:
      is­Null­If­Outside in interface Banded­Coverage​.Evaluator
      Returns:
      whether apply(Direct­Position) return null for points outside coverage bounds.

    • setNullIfOutside

      public void setNullIfOutside(boolean flag)
      Sets whether to return null instead of throwing an exception if a point is outside coverage bounds. The default value is false. Setting this flag to true may improve performances if the caller expects that many points will be outside coverage bounds, since it reduces the amount of exceptions to be created.
      Specified by:
      set­Null­If­Outside in interface Banded­Coverage​.Evaluator
      Parameters:
      flag - whether apply(Direct­Position) should use null return value instead of Point­Outside­Coverage­Exception for signaling that a point is outside coverage bounds.

    • apply

      public double[] apply(DirectPosition point) throws CannotEvaluateException
      Returns a sequence of double values for a given point in the coverage. The CRS of the given point may be any coordinate reference system; coordinate conversions will be applied as needed. If the CRS of the point is undefined, then it is assumed to be the coverage CRS. The returned sequence includes a value for each sample dimension.

      The default interpolation type used when accessing grid values for points which fall between grid cells is nearest neighbor. This default interpolation method may change in future version.

      The default implementation invokes Grid­Coverage​.render(Grid­Extent) for a small region around the point. Subclasses should override with more efficient implementation.

      Specified by:
      apply in interface Banded­Coverage​.Evaluator
      Specified by:
      apply in interface Function<Direct­Position,double[]>
      Parameters:
      point - the coordinate point where to evaluate.
      Returns:
      the sample values at the specified point, or null if the point is outside the coverage. For performance reason, this method may return the same array on every method call by overwriting previous values. Callers should not assume that the array content stay valid for a long time.
      Throws:
      Point­Outside­Coverage­Exception - if the evaluation failed because the input point has invalid coordinates and the is­Null­If­Outside() flag is false.
      Cannot­Evaluate­Exception - if the values can not be computed at the specified coordinates for another reason. This exception may be thrown if the coverage data type can not be converted to double by an identity or widening conversion. Subclasses may relax this constraint if appropriate.

    • toGridCoordinates

      public FractionalGridCoordinates toGridCoordinates(DirectPosition point) throws TransformException
      Converts the specified geospatial position to grid coordinates. If the given position is associated to a non-null coordinate reference system (CRS) different than the coverage CRS, then this method automatically transforms that position to the coverage CRS before to compute grid coordinates.

      This method does not put any restriction on the grid coordinates result. The result may be outside the grid extent if the grid to CRS transform allows it.

      Parameters:
      point - geospatial coordinates (in arbitrary CRS) to transform to grid coordinates.
      Returns:
      the grid coordinates for the given geospatial coordinates.
      Throws:
      Incomplete­Grid­Geometry­Exception - if the grid geometry does not define a "grid to CRS" transform, or if the given point has a non-null CRS but the coverage does not have a CRS.
      Transform­Exception - if the given coordinates can not be transformed.
      See Also: