org.apache.sis.referencing.cs

Interface AxisFilter

All Known Implementing Classes:

AxesConvention

public interface AxisFilter

Modifications to apply on the axes of a coordinate system in order to produce a new coordinate system. AxisFilter can specify the axes to exclude in the new coordinate system, or specify different units and directions associated to the axes.

Terminology note the word “filter” is understood here as “a computer program or subroutine to process a stream, producing another stream” (Wikipedia).

Note that filtering one or more axes may result in a change of coordinate system type. For example excluding the z axis of a cylindrical coordinate system results in a polar coordinate system.

Limitations

This interface is not for changing axis order. For changing axis order in addition to axis directions or units, see AxesConvention.

Since:

0.6

See Also:

CoordinateSystems.replaceAxes(CoordinateSystem, AxisFilter)

Defined in the sis-referencing module

Method Summary

Methods

Modifier and Type	Method and Description
boolean	accept(CoordinateSystemAxis axis) Returns true if the given axis shall be included in the new coordinate system.
AxisDirection	getDirectionReplacement(AxisDirection direction) Returns a replacement for the given axis direction.
Unit<?>	getUnitReplacement(Unit<?> unit) Returns a replacement for the given axis unit.

Method Detail

accept

boolean accept(CoordinateSystemAxis axis)

Returns true if the given axis shall be included in the new coordinate system.

Parameters:

axis - The axis to test.

Returns:

true if the given axis shall be included in the new coordinate system.

getDirectionReplacement

AxisDirection getDirectionReplacement(AxisDirection direction)

Returns a replacement for the given axis direction.

Example: for forcing the direction of the z axis toward up while leaving other axes unchanged, one can write:

@Override
public getDirectionReplacement(AxisDirection direction) {
    if (direction == AxisDirection.DOWN) {
        direction = AxisDirection.UP;
    }
    return direction;
}

Parameters:

direction - The original axis direction.

Returns:

The new axis direction, or direction if there is no change.

getUnitReplacement

Unit<?> getUnitReplacement(Unit<?> unit)

Returns a replacement for the given axis unit.

Example: for replacing all angular units of a coordinate system to degrees (regardless what the original angular units were) while leaving other kinds of units unchanged, one can write:

@Override
public Unit<?> getUnitReplacement(Unit<?> unit) {
    if (Units.isAngular(unit)) {
        unit = NonSI.DEGREE_ANGLE;
    }
    return unit;
}

Parameters:

unit - The original axis unit.

Returns:

The new axis unit, or unit if there is no change.