Class Toa

  • All Implemented Interfaces:
    java.io.Serializable, Component

    public class Toa
    extends Projecter
    This class provides for the translation between coordinates and an HTM-based projection.

    The projection is centered at the north pole. The south pole is projected to the four corners at (+/-1, +/-1). The equator projects to the diagonals running between the points (-1,0)->(0,1), (0,1)->(1,0), (1,0)->(0,-1), (-1,0)->(0,-1). These diagonals divide the four unit squares at the center of the coordinate grid into 8 right isoceles triangles.

    The position 0,0 projects to 0,1 while the position 90,0 projects to 1,0. Note that in an astronomical projection the coordinates will normally have the X axis inverted, so that 0,0 will project to -1,0.

    The 8 triangles correspond to the 8 initial triangles of the HTM decomposition of the sphere. The projection is defined such that the subtriangles in the HTM decomposition are mapped to isoceles right-triangles in the projection plane.

    This call may be called in the same fashion as standard projections or it may be called to create a tile space. In this case the object immediately computes the coordinates corresponding to all pixels in a tile and later returns these as requested.

    The tiles are numbered with tile 0,0 as the top, left tile. The vertical orientation of the tiles is therefore the opposite of the orientation of the pixel values within the tiles and within the FITS files generated. Note that when SkyView generates quicklook images it flips the Y-axis to accommodate the difference between the astronomical and imaging conventions.

    See Also:
    Serialized Form
    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      class  Toa.ToaDeproj
      Deproject from the ToastPlane back to the unit sphere
    • Constructor Summary

      Constructors 
      Constructor Description
      Toa()  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      double[] find​(double lon, double lat)  
      java.lang.String getDescription()
      Get the description of this component.
      java.lang.String getName()
      Get the name of this component.
      Deprojecter inverse()
      Get the inverse
      boolean isInverse​(Transformer obj)
      Are these two transformations, inverses of each other? This method is used to optimize a series of transformations where transformations.
      static void main​(java.lang.String[] args)  
      double[] project​(double lon, double lat)
      Calculate the x,y corresponding to a given lon/lat
      void setPrecision​(double epsilon, double minDelta)
      Specify precision used in non-grid project/deproject calculations
      double[] shadowPoint​(double x, double y)
      Return a shadowpoint for the input location.
      static void show​(java.lang.String prefix, double[] vector)  
      boolean straddle​(double[][] vertices)
      Does this pixel go wrap around the standard region of the image? E.g., does it straddle the 180 deg in a Car or Ait projection?
      boolean straddleable()
      Is it possible for a pixel to straddle the valid region.
      double[][][] straddleComponents​(double[][] vertices)
      If this is a straddling pixel, then return the straddle components
      double[][][] tile​(int level, int ix, int iy, int subdiv)  
      void transform​(double[] unit, double[] plane)
      Convert a single point where the output vector is supplied.
      boolean validPosition​(double[] plane)
      Is this a valid position in the projection plane for this image.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • Toa

        public Toa()
    • Method Detail

      • validPosition

        public boolean validPosition​(double[] plane)
        Description copied from class: Projecter
        Is this a valid position in the projection plane for this image. This default is appropriate for all projections where the projection plane is infinite.
        Overrides:
        validPosition in class Projecter
      • setPrecision

        public void setPrecision​(double epsilon,
                                 double minDelta)
        Specify precision used in non-grid project/deproject calculations
      • project

        public double[] project​(double lon,
                                double lat)
        Calculate the x,y corresponding to a given lon/lat
        Parameters:
        lon - The longitude in radians.
        lat - The latitude in radians.
        Returns:
        A pair of coordinates in the projection plane where there coordinates are in the range [-1,1].
      • find

        public double[] find​(double lon,
                             double lat)
      • getName

        public java.lang.String getName()
        Description copied from interface: Component
        Get the name of this component.
      • getDescription

        public java.lang.String getDescription()
        Description copied from interface: Component
        Get the description of this component.
      • isInverse

        public boolean isInverse​(Transformer obj)
        Description copied from class: Transformer
        Are these two transformations, inverses of each other? This method is used to optimize a series of transformations where transformations.
        Specified by:
        isInverse in class Transformer
      • transform

        public void transform​(double[] unit,
                              double[] plane)
        Description copied from class: Transformer
        Convert a single point where the output vector is supplied.
        Specified by:
        transform in class Transformer
        Parameters:
        unit - The input vector.
        plane - The output vector, it may be the same as the input vector if the dimensionalities are the same. All transformers are expected to work with aliased inputs and output.
      • tile

        public double[][][] tile​(int level,
                                 int ix,
                                 int iy,
                                 int subdiv)
      • show

        public static void show​(java.lang.String prefix,
                                double[] vector)
      • main

        public static void main​(java.lang.String[] args)
                         throws java.lang.Exception
        Throws:
        java.lang.Exception
      • straddleable

        public boolean straddleable()
        Description copied from class: Projecter
        Is it possible for a pixel to straddle the valid region.
        Overrides:
        straddleable in class Projecter
      • shadowPoint

        public double[] shadowPoint​(double x,
                                    double y)
        Description copied from class: Projecter
        Return a shadowpoint for the input location. Shadowpoints are not defined for all projections.
        Overrides:
        shadowPoint in class Projecter
      • straddle

        public boolean straddle​(double[][] vertices)
        Description copied from class: Projecter
        Does this pixel go wrap around the standard region of the image? E.g., does it straddle the 180 deg in a Car or Ait projection?
        Overrides:
        straddle in class Projecter
      • straddleComponents

        public double[][][] straddleComponents​(double[][] vertices)
        Description copied from class: Projecter
        If this is a straddling pixel, then return the straddle components
        Overrides:
        straddleComponents in class Projecter