Class Toa
- All Implemented Interfaces:
Serializable
,Component
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:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionclass
Deproject from the ToastPlane back to the unit sphere -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptiondouble[]
find
(double lon, double lat) Get the description of this component.getName()
Get the name of this component.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
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
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
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
Methods inherited from class skyview.geometry.Transformer
transform, transform
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Constructor Details
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Toa
public Toa()
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Method Details
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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 -
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) -
getName
Description copied from interface:Component
Get the name of this component. -
getDescription
Description copied from interface:Component
Get the description of this component. -
isInverse
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
Description copied from class:Projecter
Get the inverse -
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) -
show
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main
- Throws:
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? -
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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