Hi,
Sorry, the correct main() function is:
Void main()
{
QDateTime date = QDateTime(QDate(2016, 4, 15), QTime(10,0,0,0),
QTimeZone::utc());
setTime(date);
update()
Vec3d in;
double ra = 16.123456;
double dec = 36.46667;
spheToRect(ra*M_PI/180.0, dec*M_PI/180.0, in);
Vec3d out2; // <---------------------------------------------
out2 = j2000ToAltAz(in); //
<---------------------------------------------
double alt1, az1;
rectToSphe(&az1, &alt1, out2);
qDebug() << "j2000ToAltAz.alt:" << alt1*180/M_PI;
qDebug() << "j2000ToAltAz.az:" << az1*180/M_PI;
}
De: Andre Moutinho [mailto:mouti...@gmail.com]
Enviada em: sábado, 14 de maio de 2016 11:04
Para: Stellarium developers public mailing list
(stellarium-pubdevel@lists.sourceforge.net)
Assunto: Simple J2000 to Altaz conversion help
Hello all,
I am trying to get the function j2000ToAltAz() work as simple as possible.
But my test case is not returning a valid RA/DEC to ALT/AZ conversion.
I have made getRotEquatorialToVsop87() returns Mat4d::identity() as a first
approach to make code simple. I have noticed that getRotEquatorialToVsop87()
uses JDE and this variable has a previous state (time) that I will not have
in my application so I dont know how to solve this because my application
will only plot a static stellar map for a certain date/time/location. Maybe
returning an identity matrix would not change much the result.
I may be trying something stupid but please forgive me because I dont have
much knowledge in this subject. Hope someone can help me.
Thanks a lot
Andre
Here is the code:
// Matrices used for every coordinate transfo
Mat4d matAltAzToEquinoxEqu; // Transform from topocentric
altazimuthal coordinate to Earth Equatorial
Mat4d matEquinoxEquToAltAz; // Transform from Earth
Equatorial to topocentric (StelObserver) altazimuthal coordinate
Mat4d matEquinoxEquToJ2000; // For Earth, this is almost the
inverse precession matrix, =Rz(VSOPbias)Rx(eps0)Rz(-psiA)Rx(-omA)Rz(chiA)
Mat4d matJ2000ToEquinoxEqu; // precession matrix
Mat4d matJ2000ToAltAz;
Mat4d matAltAzModelView; // Modelview matrix for
observer-centric altazimuthal drawing
Mat4d invertMatAltAzModelView; // Inverted modelview matrix for
observer-centric altazimuthal drawing
const double JD_SECOND=0.000011574074074074074074; // 1/(24*60*60)=1/86400
const double JD_MINUTE=0.00069444444444444444444; // 1/(24*60) =1/1440
const double JD_HOUR =0.041666666666666666666; // 1/24
const double JD_DAY =1.;
const double ONE_OVER_JD_SECOND = 24 * 60 * 60; // 86400
QPair<double,double> JD; // From 0.14 on: JD.first=JD_UT,
JD.second=DeltaT=TT-UT. To gain JD_TT, compute JDE=JD.first+JD.second or
better just call getJDE()
#define LATITUDE 51.76954
#define LONGITUDE 4.605606
const Mat4d
matJ2000ToVsop87(Mat4d::xrotation(-23.4392803055555555556*(M_PI/180)) *
Mat4d::zrotation(0.0000275*(M_PI/180)));
const Mat4d matVsop87ToJ2000(matJ2000ToVsop87.transpose());
Mat4d getRotEquatorialToVsop87()
{
Mat4d rval = Mat4d::identity();
return rval;
}
Mat4d getRotAltAzToEquatorial(double JD)
{
double lat = LATITUDE;
double lng = LONGITUDE;
if( lat > 90.0 ) lat = 90.0;
if( lat < -90.0 ) lat = -90.0;
return Mat4d::zrotation((getSiderealTime(JD)+lng)*M_PI/180.)*
Mat4d::yrotation((90.-lat)*M_PI/180.);
}
update()
{
matAltAzToEquinoxEqu = getRotAltAzToEquatorial(getJD());
matEquinoxEquToAltAz = matAltAzToEquinoxEqu.transpose();
matEquinoxEquToJ2000 = matVsop87ToJ2000 *
getRotEquatorialToVsop87();
matJ2000ToEquinoxEqu = matEquinoxEquToJ2000.transpose();
matJ2000ToAltAz = matEquinoxEquToAltAz*matJ2000ToEquinoxEqu;
}
Vec3d j2000ToAltAz(const Vec3d& v)
{
return matJ2000ToAltAz*v;
}
void setTime(QDateTime d)
{
setJD(StelUtils::qDateTimeToJd(d));
}
Void main()
{
QDateTime date = QDateTime(QDate(2016, 4, 15), QTime(10,0,0,0),
QTimeZone::utc());
setTime(date);
update()
Vec3d in;
double ra = 16.123456;
double dec = 36.46667;
spheToRect(ra*M_PI/180.0, dec*M_PI/180.0, in);
double alt1, az1;
rectToSphe(&az1, &alt1, out2);
qDebug() << "j2000ToAltAz.alt:" << alt1*180/M_PI;
qDebug() << "j2000ToAltAz.az:" << az1*180/M_PI;
}
---
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