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/*!
* \file TelescopeDirectionVectorSupportFunctions.h
*
* \author Roger James
* \date 13th November 2013
*
*/
#pragma once
#include "Common.h"
#include "libastro.h"
#include "indicom.h"
namespace INDI
{
namespace AlignmentSubsystem
{
/*! \class TelescopeDirectionVectorSupportFunctions
* \brief These functions are used to convert different coordinate systems to and from the
* telescope direction vectors (normalised vector/direction cosines) used for telescope coordinates in the
* alignment subsystem.
*/
class TelescopeDirectionVectorSupportFunctions
{
public:
/// \brief Virtual destructor
virtual ~TelescopeDirectionVectorSupportFunctions() {}
/*!
* \enum AzimuthAngleDirection
* The direction of measurement of an azimuth angle.
* The following are the conventions for some coordinate systems.
* - Right Ascension is measured ANTI_CLOCKWISE from the vernal equinox.
* - Local Hour Angle is measured CLOCKWISE from the observer's meridian.
* - Greenwich Hour Angle is measured CLOCKWISE from the Greenwich meridian.
* - Azimuth (as in Altitude Azimuth coordinate systems ) is often measured CLOCKWISE\n
* from north. But ESO FITS (Clockwise from South) and SDSS FITS(Anticlockwise from South)\n
* have different conventions. Horizontal coordinates in libnova are measured clockwise from south.
*/
typedef enum AzimuthAngleDirection
{
CLOCKWISE, /*!< Angle is measured clockwise */
ANTI_CLOCKWISE /*!< Angle is measured anti clockwise */
} AzimuthAngleDirection_t;
/*!
* \enum PolarAngleDirection
* The direction of measurement of a polar angle.
* The following are conventions for some coordinate systems
* - Declination is measured FROM_AZIMUTHAL_PLANE.
* - Altitude is measured FROM_AZIMUTHAL_PLANE.
* - Altitude in libnova horizontal coordinates is measured FROM_AZIMUTHAL_PLANE.
*/
typedef enum PolarAngleDirection
{
FROM_POLAR_AXIS, /*!< Angle is measured down from the polar axis */
FROM_AZIMUTHAL_PLANE /*!< Angle is measured upwards from the azimuthal plane */
} PolarAngleDirection_t;
/*! \brief Calculates an altitude and azimuth from the supplied normalised direction vector
* and declination.
* \param[in] TelescopeDirectionVector
* \param[out] HorizontalCoordinates Altitude and Azimuth in decimal degrees
* \note This assumes a right handed coordinate system for the telescope direction vector with XY being the azimuthal plane,
* and azimuth being measured in a clockwise direction.
*/
void AltitudeAzimuthFromTelescopeDirectionVector(const TelescopeDirectionVector TelescopeDirectionVector,
INDI::IHorizontalCoordinates &HorizontalCoordinates)
{
double AzimuthAngle;
double AltitudeAngle;
SphericalCoordinateFromTelescopeDirectionVector(TelescopeDirectionVector, AzimuthAngle, CLOCKWISE,
AltitudeAngle, FROM_AZIMUTHAL_PLANE);
HorizontalCoordinates.azimuth = range360(RAD_TO_DEG(AzimuthAngle));
HorizontalCoordinates.altitude = RAD_TO_DEG(AltitudeAngle);
};
/*! \brief Calculates equatorial coordinates from the supplied telescope direction vector
* and declination.
* \param[in] TelescopeDirectionVector
* \param[out] EquatorialCoordinates The equatorial coordinates in hours minutes seconds and degrees minutes seconds
* \note This assumes a right handed coordinate system for the direction vector with the right ascension being in the XY plane.
*/
void EquatorialCoordinatesFromTelescopeDirectionVector(const TelescopeDirectionVector TelescopeDirectionVector,
INDI::IEquatorialCoordinates &EquatorialCoordinates)
{
double AzimuthAngle;
double PolarAngle;
SphericalCoordinateFromTelescopeDirectionVector(TelescopeDirectionVector, AzimuthAngle, ANTI_CLOCKWISE,
PolarAngle, FROM_AZIMUTHAL_PLANE);
EquatorialCoordinates.rightascension = range24(RAD_TO_DEG(AzimuthAngle) / 15.0);
EquatorialCoordinates.declination = rangeDec(RAD_TO_DEG(PolarAngle));
};
/*! \brief Calculates a local hour angle and declination from the supplied telescope direction vector
* and declination.
* \param[in] TelescopeDirectionVector
* \param[out] EquatorialCoordinates The local hour angle and declination in decimal degrees
* \note This assumes a right handed coordinate system for the direction vector with the hour angle being in the XY plane.
*/
void LocalHourAngleDeclinationFromTelescopeDirectionVector(const TelescopeDirectionVector TelescopeDirectionVector,
INDI::IEquatorialCoordinates &EquatorialCoordinates)
{
double AzimuthAngle;
double PolarAngle;
SphericalCoordinateFromTelescopeDirectionVector(TelescopeDirectionVector, AzimuthAngle, CLOCKWISE, PolarAngle,
FROM_AZIMUTHAL_PLANE);
EquatorialCoordinates.rightascension = range24(RAD_TO_DEG(AzimuthAngle) / 15.0);
EquatorialCoordinates.declination = rangeDec(RAD_TO_DEG(PolarAngle));
};
/*! \brief Calculates a spherical coordinate from the supplied telescope direction vector
* \param[in] TelescopeDirectionVector
* \param[out] AzimuthAngle The azimuth angle in radians
* \param[in] AzimuthAngleDirection The direction the azimuth angle has been measured either CLOCKWISE or ANTI_CLOCKWISE
* \param[out] PolarAngle The polar angle in radians
* \param[in] PolarAngleDirection The direction the polar angle has been measured either FROM_POLAR_AXIS or FROM_AZIMUTHAL_PLANE
* \note TelescopeDirectionVectors are always normalised and right handed.
*/
void SphericalCoordinateFromTelescopeDirectionVector(const TelescopeDirectionVector TelescopeDirectionVector,
double &AzimuthAngle,
AzimuthAngleDirection_t AzimuthAngleDirection,
double &PolarAngle, PolarAngleDirection_t PolarAngleDirection);
/*! \brief Calculates a normalised direction vector from the supplied altitude and azimuth.
* \param[in] HorizontalCoordinates Altitude and Azimuth in decimal degrees
* \return A TelescopeDirectionVector
* \note This assumes a right handed coordinate system for the telescope direction vector with XY being the azimuthal plane,
* and azimuth being measured in a clockwise direction.
*/
const TelescopeDirectionVector TelescopeDirectionVectorFromAltitudeAzimuth(INDI::IHorizontalCoordinates
HorizontalCoordinates)
{
return TelescopeDirectionVectorFromSphericalCoordinate(DEG_TO_RAD(HorizontalCoordinates.azimuth), CLOCKWISE,
DEG_TO_RAD(HorizontalCoordinates.altitude),
FROM_AZIMUTHAL_PLANE);
};
/*! \brief Calculates a telescope direction vector from the supplied equatorial coordinates.
* \param[in] EquatorialCoordinates The equatorial coordinates in hours minutes seconds and degrees minutes seconds
* \return A TelescopeDirectionVector
* \note This assumes a right handed coordinate system for the direction vector with the right ascension being in the XY plane.
*/
const TelescopeDirectionVector
TelescopeDirectionVectorFromEquatorialCoordinates(INDI::IEquatorialCoordinates EquatorialCoordinates)
{
return TelescopeDirectionVectorFromSphericalCoordinate(DEG_TO_RAD(EquatorialCoordinates.rightascension * 15.0),
ANTI_CLOCKWISE,
DEG_TO_RAD(EquatorialCoordinates.declination),
FROM_AZIMUTHAL_PLANE);
};
/*! \brief Calculates a telescope direction vector from the supplied local hour angle and declination.
* \param[in] EquatorialCoordinates The local hour angle and declination in decimal degrees
* \return A TelescopeDirectionVector
* \note This assumes a right handed coordinate system for the direction vector with the hour angle being in the XY plane.
*/
const TelescopeDirectionVector
TelescopeDirectionVectorFromLocalHourAngleDeclination(INDI::IEquatorialCoordinates EquatorialCoordinates)
{
return TelescopeDirectionVectorFromSphericalCoordinate(DEG_TO_RAD(EquatorialCoordinates.rightascension * 15.0), CLOCKWISE,
DEG_TO_RAD(EquatorialCoordinates.declination),
FROM_AZIMUTHAL_PLANE);
};
/*! \brief Calculates a telescope direction vector from the supplied spherical coordinate information
* \param[in] AzimuthAngle The azimuth angle in radians
* \param[in] AzimuthAngleDirection The direction the azimuth angle has been measured either CLOCKWISE or ANTI_CLOCKWISE
* \param[in] PolarAngle The polar angle in radians
* \param[in] PolarAngleDirection The direction the polar angle has been measured either FROM_POLAR_AXIS or FROM_AZIMUTHAL_PLANE
* \return A TelescopeDirectionVector
* \note TelescopeDirectionVectors are always assumed to be normalised and right handed.
*/
const TelescopeDirectionVector
TelescopeDirectionVectorFromSphericalCoordinate(const double AzimuthAngle,
AzimuthAngleDirection_t AzimuthAngleDirection,
const double PolarAngle, PolarAngleDirection_t PolarAngleDirection);
};
} // namespace AlignmentSubsystem
} // namespace INDI
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