[Mobilitydb-users] MobiltyDB for Windows

[Mahmoud SAKR]

Hi Alan,
WGS84 is a geographic coordinate system (lon, lat). One shouldn't compute
distances with it.
You need to project the data to some geometric coordinate system, where the
units are meters.

Best regards,
Mahmoud SAKR


On Wed, Sep 1, 2021 at 3:03 PM <suc.eleve at ecole-navale.fr> wrote:

> I use mobiltyBD for docker, version 1.0 beta3. The SRID is WGS84
> (4326). I will find attached, a csv and a backup of a table I created
> with only three ships, the one of the screen shot is one of them, one
> other come close to this one (212m), and other one stays far away (59km)
> Best Regards,
> A. Suc
>
> Esteban Zimanyi <estebanzimanyi at gmail.com> a écrit :
>
> > Please tell us which version you downloaded, if Mahmoud's function worked
> > then most probably you had the master version while we are in the process
> > of preparing the next beta version and thus working on the develop
> branch.
> >
> > Furthermore, please tell us which SRID you are using. In order to help
> you
> > we need a sample data so we can test the function that is not working for
> > you. Ideally the sample data should be as small as possible, possibly
> with
> > only the one ship you have shown in your screenshot.
> >
> > ------------------------------------------------------------
> > Prof. Esteban Zimanyi
> > Department of Computer & Decision Engineering  (CoDE) CP 165/15
> > Universite Libre de Bruxelles
> > Avenue F. D. Roosevelt 50
> > B-1050 Brussels, Belgium
> > fax: + 32.2.650.47.13
> > tel: + 32.2.650.31.85
> > e-mail: esteban.zimanyi at ulb.be
> > Internet:
> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcs.ulb.ac.be%2Fmembers%2Festeban%2F&data=04%7C01%7Cmahmoud.sakr%40ulb.be%7Cc7ec92e3a8e94a86eeb508d96d48ffde%7C30a5145e75bd4212bb028ff9c0ea4ae9%7C0%7C0%7C637660982969092283%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=za8z8uSxz6QQrYGGaQtDcagccIye1OQr8p1oHX%2B5Ekk%3D&reserved=0
> > ------------------------------------------------------------
> >
> >
> > On Wed, Sep 1, 2021 at 1:56 PM Alan Suc <suc.eleve at ecole-navale.fr>
> wrote:
> >
> >> Sir,
> >>
> >> Thank you for your answer. I tried yours first but it didn't work,
> while M
> >> Sakr's one worked, which is quite strange as I reinstalled MobilityDB
> last
> >> week so I guess I should have the most recent version. An other
> question,
> >> I'm using dwithin() and |=|but those fonctions seems to don't work.
> Indeed,
> >> for the dectection of near miss situation between ships I use dwithin to
> >> detect ships who came closer than 1000m to the one studied, but this
> >> function seems to don't work as it also select ships which were at
> dozens
> >> of kilometers. Also |=| seems lost as it returns a distance of 0.53 m at
> >> closest point of approach while QGIS measures 59km for the same line. I
> >> join a screen capture which, I guess, is more more explicit.
> >>
> >> Best Regards,
> >>
> >> A. Suc
> >>
> >> Le 31/08/2021 à 18:28, Esteban Zimanyi a écrit :
> >>
> >> Please find enclosed a new version of the function since the suffixes
> for
> >> the subtypes in MobilityDB have been changed to _inst, _instset, _seq,
> and
> >> _seqset for better readability. Usage examples of the function are also
> >> included in the file.
> >>
> >> On Tue, Aug 31, 2021 at 4:53 PM Mahmoud SAKR <mahmoud.sakr at ulb.ac.be>
> >> wrote:
> >>
> >>> [...]
> >>>
> >>
> >>
> >>> I understand that you got a sequence of (location, timestamp) pairs,
> from
> >>> which you want to construct a trajectory. But you want to split into
> >>> multiple trajectories whenever there is a big gap (in time or in
> distance)
> >>> between two consecutive points.
> >>>
> >>> Enclosed is an SQL function to do this.
> >>>
> >>
>
>
>
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