[Stellarium-pubdevel] RES: Simple J2000 to Altaz conversion help

[Andre M. <mou...@gm...>]

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:mou...@gm...] 
Enviada em: sábado, 14 de maio de 2016 11:04
Para: Stellarium developers public mailing list
(ste...@li...)
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 don’t 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 don’t 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;
}



---
Este email foi escaneado pelo Avast antivírus.
https://www.avast.com/antivirus