stella.parameter
Class Horizon.Ellipsoidal

java.lang.Object
  stella.parameter.Horizon.Ellipsoidal

Direct Known Subclasses:

Horizon.Stella1, Horizon.Stella2

Enclosing class:

Horizon

private static class Horizon.Ellipsoidal
extends Object

The class to calculate the shadow of two elliptical roofs, like in STELLA.

Field Summary

private static double	AHALF The half-diameter of the building roof ellipse, horizontal.
private static double	BHALF The half-diameter of the building roof ellipse, vertical.
private static double	D0 Distance on long axis to closer roof half.
private static double	D1 Distance on long axis to far roof.
private double	far From the dimensions of the building, the far viewing angle.
private static double	L0 Distance on short axis to building wall.
private static double	M0 Height of the wall.
private double	near From the dimensions of the building, the close viewing angle.
private double	phi0 The azimuth offset of the long edge to closer roof.
private static double	R0 Radius of mirror.
private static double	Z0 Offset above zero for roof-halfs.

Constructor Summary

private

Horizon.Ellipsoidal(double az0)

Method Summary

protected double	obscured(Vector2D wall, double h) This method calculates the amount of shading from simplified geometric considerations.
double	shadow(double az, double h) Combines the calculation of the wall height plus vignetting.
protected Vector2D	wall(double az) This method returns the height of the wall/roof in the second componentand the distance to the footpoint of the roof in the first.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

AHALF

private static final double AHALF

The half-diameter of the building roof ellipse, horizontal.

See Also:

Constant Field Values

BHALF

private static final double BHALF

The half-diameter of the building roof ellipse, vertical.

See Also:

Constant Field Values

Z0

private static final double Z0

Offset above zero for roof-halfs.

See Also:

Constant Field Values

D0

private static final double D0

Distance on long axis to closer roof half.

See Also:

Constant Field Values

D1

private static final double D1

Distance on long axis to far roof.

See Also:

Constant Field Values

M0

private static final double M0

Height of the wall.

See Also:

Constant Field Values

L0

private static final double L0

Distance on short axis to building wall.

See Also:

Constant Field Values

R0

private static final double R0

Radius of mirror.

See Also:

Constant Field Values

phi0

private double phi0

The azimuth offset of the long edge to closer roof.

near

private double near

From the dimensions of the building, the close viewing angle.

far

private double far

From the dimensions of the building, the far viewing angle.

Constructor Detail

Horizon.Ellipsoidal

private Horizon.Ellipsoidal(double az0)

Method Detail

wall

protected Vector2D wall(double az)

This method returns the height of the wall/roof in the second componentand the distance to the footpoint of the roof in the first.

Parameters:

az - Azimuth in degrees.

obscured

protected double obscured(Vector2D wall,
                          double h)

This method calculates the amount of shading from simplified geometric considerations. From the current top-point of the wall, as returned by wall(double), we calculate the angle under which the mirror of the telescope will be seen. If the current pointing height is below the wall height minus the viewing angle, total shading is assumed. If the pointing height is above the wall height plus this angle, zero shading is returned. For pointings between those two, we estimate the shaded area by calculating the height of the wall point on the mirror and assuming a horizontal line there. This assumption is correct, if the wall height is only a slowly varying function of azimuth, which is mostly the case.

Parameters:

h - in degrees.

shadow

public double shadow(double az,
                     double h)

Combines the calculation of the wall height plus vignetting.