uk.ac.starlink.ttools.plot2.geom
Interface Projection

All Known Implementing Classes:
HemisphereProjection, SinProjection, SkyviewProjection

public interface Projection

Sky projection. Defines the mapping of normalised X,Y,Z coordinates (direction cosines) to dimensionless coordinates on a 2D plane.

Since:
21 Feb 2013
Author:
Mark Taylor

Method Summary
 SkyAspect createAspect(boolean reflect, double[] r3, double radiusRad, Range[] vxyzRanges)
          Creates a SkyAspect from configuration information.
 double[] cursorRotate(double[] rotmat, Point2D.Double pos0, Point2D.Double pos1)
          Attempts to return a rotation matrix corresponding to moving the cursor between two plane positions.
 String getProjectionDescription()
          Returns a short description of the projection.
 String getProjectionName()
          Returns the projection name.
 Shape getProjectionShape()
          Returns the shape which encloses all the plane positions to which legal sky coordinates can be projected.
 boolean project(double rx, double ry, double rz, Point2D.Double pos)
          Transforms a sky position to a plane position.
 double[] projRotate(double[] rotmat, Point2D.Double pos0, Point2D.Double pos1)
          Attempts to return a rotation matrix that will transform a sky position from one plane position to another.
 boolean unproject(Point2D.Double pos, double[] r3)
          Transforms a plane position to a sky position.
 boolean useRanges(boolean reflect, double[] r3, double radiusRad)
          Indicates whether ranges should be provided to generate a SkyAspect.
 

Method Detail

getProjectionName

String getProjectionName()
Returns the projection name.

Returns:
user-directed projection name

getProjectionDescription

String getProjectionDescription()
Returns a short description of the projection. return projection description


project

boolean project(double rx,
                double ry,
                double rz,
                Point2D.Double pos)
Transforms a sky position to a plane position.

Parameters:
rx - normalised 3D X coordinate
ry - normalised 3D Y coordinate
rz - normalised 3D Z coordinate
pos - point object into which projected dimensionless X,Y coordinates will be written on success
Returns:
true if transformation succeeded

unproject

boolean unproject(Point2D.Double pos,
                  double[] r3)
Transforms a plane position to a sky position.

Parameters:
pos - contains dimensionless X,Y coordinates of plane position
r3 - 3-element array into which normalised X,Y,Z sky coordinates will be written on success
Returns:
true if transformation succeeded

getProjectionShape

Shape getProjectionShape()
Returns the shape which encloses all the plane positions to which legal sky coordinates can be projected. Typically this has linear dimensions of the order of PI.

Returns:
projected sky shape

cursorRotate

double[] cursorRotate(double[] rotmat,
                      Point2D.Double pos0,
                      Point2D.Double pos1)
Attempts to return a rotation matrix corresponding to moving the cursor between two plane positions. Ideally this should do the same thing as projRotate, for both positions on the sky, and provide some other intuitive behaviour if one or both is out of the projection range.

Null may be returned if this projection does not support rotation.

Parameters:
rotmat - initial rotation matrix
pos0 - initial cursor position
pos1 - destination cursor position
Returns:
destination rotation matrix, or null

projRotate

double[] projRotate(double[] rotmat,
                    Point2D.Double pos0,
                    Point2D.Double pos1)
Attempts to return a rotation matrix that will transform a sky position from one plane position to another.

Consider a sky point S, rotated by an initial rotation matrix rotmat to S', which when projected by this projection lands on the plane at pos0. This method attempts to determine a rotation matrix which when used instead of rotmat would end up with the rotated and projected point at pos1.

Null may be returned if this projection does not support projection.

Parameters:
rotmat - initial rotation matrix
pos0 - initial projected position
pos1 - destination projected position
Returns:
destination rotation matrix, or null

useRanges

boolean useRanges(boolean reflect,
                  double[] r3,
                  double radiusRad)
Indicates whether ranges should be provided to generate a SkyAspect. If supplied field of view arguments are sufficient, or if a default aspect is always produced, return false.

Parameters:
reflect - whether requested aspect will be reflected
r3 - central position of field of view (may be null)
radiusRad - radius of field of view (may be NaN)
Returns:
true if ranges would be useful given the other arguments
See Also:
SurfaceFactory.readRanges(P, uk.ac.starlink.ttools.plot2.PlotLayer[], uk.ac.starlink.ttools.plot2.data.DataStore)

createAspect

SkyAspect createAspect(boolean reflect,
                       double[] r3,
                       double radiusRad,
                       Range[] vxyzRanges)
Creates a SkyAspect from configuration information. Either the supplied field of view or data ranges may be used, or neither.

Parameters:
reflect - whether requested aspect will be reflected
r3 - central position of field of view (may be null)
radiusRad - radius of field of view (may be NaN)
vxyzRanges - definite ranges for normalised X,Y,Z coordinates acquired from data
Returns:
new sky aspect
See Also:
SurfaceFactory.createAspect(P, uk.ac.starlink.ttools.plot2.config.ConfigMap, uk.ac.starlink.ttools.plot.Range[])


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