[Mobilitydb-users] MobilityDB-Coordinates from TGeompoint

[suc.eleve at ecole-navale.fr]

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
>>
>> _______________________________________________
>> Mobilitydb-users mailing list
>> Mobilitydb-users at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/mobilitydb-users
>>