[Mobilitydb-users] MobilityDB-Coordinates from TGeompoint

[Esteban Zimanyi]

Currently there is no such a function but I think it can be easily
implemented.

Suppose that ship1 is at p1 at t1 and ship2 is at p2 at t1. What the value of
such a function be at time t1 ?

On Mon, Sep 20, 2021 at 2:14 PM <suc.eleve at ecole-navale.fr> wrote:

> Thanks for your answer, I missed the temporal distance. But the
> built-in function azimuth is not what I want to do : I would like to
> obtain a tfloat which would correspond at the direction in which ShipA
> see ShipB at each instant.
> Best Regards,
>
>
> Esteban Zimanyi <esteban.zimanyi at ulb.be> a écrit :
>
> > You can use the temporal distance
> > https://docs.mobilitydb.com/MobilityDB/develop/ch05s17.html
> > and azimuth functions in MobilityDB
> > https://docs.mobilitydb.com/MobilityDB/develop/ch05s06.html
> >
> > Get the temporal distance
> > {point,tpoint} <-> {point,tpoint}: tfloat
> > SELECT tgeompoint '[Point(0 0)@2012-01-01, Point(1 1)@2012-01-03)' <->
> >   geometry 'Point(0 1)';
> > -- "[1 at 2012-01-01, 0.707106781186548 at 2012-01-02, 1 at 2012-01-03)"
> > SELECT tgeompoint '[Point(0 0)@2012-01-01, Point(1 1)@2012-01-03)' <->
> >   tgeompoint '[Point(0 1)@2012-01-01, Point(1 0)@2012-01-03)';
> > -- "[1 at 2012-01-01, 0 at 2012-01-02, 1 at 2012-01-03)"
> > SELECT tgeompoint '[Point(0 1)@2012-01-01, Point(0 0)@2012-01-03)' <->
> >   tgeompoint '[Point(0 0)@2012-01-01, Point(1 0)@2012-01-03)';
> > -- "[1 at 2012-01-01, 0.707106781186548 at 2012-01-02, 1 at 2012-01-03)"
> > SELECT tgeompoint '[Point(0 0)@2012-01-01, Point(1 1)@2012-01-02)' <->
> >   tgeompoint '[Point(0 1)@2012-01-01, Point(1 2)@2012-01-02)';
> > -- "[1 at 2012-01-01,1 at 2012-01-02)"
> >
> > Get the temporal azimuth
> > azimuth(tpoint): tfloat
> > SELECT degrees(azimuth(tgeompoint '[Point(0 0 0)@2012-01-01, Point(1 1
> > 1)@2012-01-02,
> >   Point(1 1 1)@2012-01-03, Point(0 0 0)@2012-01-04)'));
> > -- "Interp=Stepwise;{[45 at 2012-01-01, 45 at 2012-01-02], [225 at 2012-01-03,
> > 225 at 2012-01-04)}"
> >
> >
> >
> > On Mon, Sep 20, 2021 at 1:32 PM <suc.eleve at ecole-navale.fr> wrote:
> >
> >> Good afternoon,
> >> As my currently working on a project on collision between ships, I
> >> would like to build a tfloat which would correspond to the distance
> >> between two ships, an other which would correspond to the bearing of
> >> one ship saw by the other one. I already have the tgeompoint
> >> corresponding to the trajectories of those ships but as I didn't find
> >> mobilityDB built-in functions which would directly do what I want, I
> >> would like to do that my self. The first step would be to obtain the X
> >> and Y coordinates of the tgeompoint into tfloat. But I don't really
> >> know how to do that as PosGis function ST_X() only works for points
> >> and not trajectories. Then I will also need to apply mathematics
> >> functions such as sin()or sqrt() to tfloat, but it seems that for the
> >> moment only basic functions such as + or / are supported for tfloat.
> >>
> >> Would someone have solutions for these diverse issues ?
> >>
> >> Best Regards,
> >>
> >> A. Suc
> >>
> >> _______________________________________________
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> >> Mobilitydb-users at lists.osgeo.org
> >> https://lists.osgeo.org/mailman/listinfo/mobilitydb-users
> >>
>
>
>
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