Class Toa
- java.lang.Object
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- skyview.geometry.Transformer
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- skyview.geometry.Projecter
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- skyview.geometry.projecter.Toa
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- 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
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Nested Class Summary
Nested Classes Modifier and Type Class Description class
Toa.ToaDeproj
Deproject from the ToastPlane back to the unit sphere
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Constructor Summary
Constructors Constructor Description Toa()
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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 inverseboolean
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/latvoid
setPrecision(double epsilon, double minDelta)
Specify precision used in non-grid project/deproject calculationsdouble[]
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 componentsdouble[][][]
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 skyview.geometry.Projecter
allValid, getInputDimension, getOutputDimension, getXTiling, getYTiling, tissot
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Methods inherited from class skyview.geometry.Transformer
transform, transform
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Method Detail
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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 classProjecter
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setPrecision
public void setPrecision(double epsilon, double minDelta)
Specify precision used in non-grid project/deproject calculations
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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].
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find
public double[] find(double lon, double lat)
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getName
public java.lang.String getName()
Description copied from interface:Component
Get the name of this component.
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getDescription
public java.lang.String getDescription()
Description copied from interface:Component
Get the description of this component.
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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 classTransformer
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inverse
public Deprojecter inverse()
Description copied from class:Projecter
Get the inverse
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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 classTransformer
- 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.
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tile
public double[][][] tile(int level, int ix, int iy, int subdiv)
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show
public static void show(java.lang.String prefix, double[] vector)
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main
public static void main(java.lang.String[] args) throws java.lang.Exception
- Throws:
java.lang.Exception
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straddleable
public boolean straddleable()
Description copied from class:Projecter
Is it possible for a pixel to straddle the valid region.- Overrides:
straddleable
in classProjecter
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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 classProjecter
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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?
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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 classProjecter
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