<div dir="ltr"><div dir="ltr"><div>Hi Alan,</div><div>WGS84 is a geographic coordinate system (lon, lat). One shouldn't compute distances with it.</div><div>You need to project the data to some geometric coordinate system, where the units are meters. <br></div><div><br></div><div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>Best regards,<span style="font-weight:bold"><br></span></div><div><span style="font-weight:bold">Mahmoud SAKR</span></div></div></div></div></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 1, 2021 at 3:03 PM <<a href="mailto:suc.eleve@ecole-navale.fr">suc.eleve@ecole-navale.fr</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I use mobiltyBD for docker, version 1.0 beta3. The SRID is WGS84 <br>
(4326). I will find attached, a csv and a backup of a table I created <br>
with only three ships, the one of the screen shot is one of them, one <br>
other come close to this one (212m), and other one stays far away (59km)<br>
Best Regards,<br>
A. Suc<br>
<br>
Esteban Zimanyi <<a href="mailto:estebanzimanyi@gmail.com" target="_blank">estebanzimanyi@gmail.com</a>> a écrit :<br>
<br>
> Please tell us which version you downloaded, if Mahmoud's function worked<br>
> then most probably you had the master version while we are in the process<br>
> of preparing the next beta version and thus working on the develop branch.<br>
><br>
> Furthermore, please tell us which SRID you are using. In order to help you<br>
> we need a sample data so we can test the function that is not working for<br>
> you. Ideally the sample data should be as small as possible, possibly with<br>
> only the one ship you have shown in your screenshot.<br>
><br>
> ------------------------------------------------------------<br>
> Prof. Esteban Zimanyi<br>
> Department of Computer & Decision Engineering (CoDE) CP 165/15<br>
> Universite Libre de Bruxelles<br>
> Avenue F. D. Roosevelt 50<br>
> B-1050 Brussels, Belgium<br>
> fax: + 32.2.650.47.13<br>
> tel: + 32.2.650.31.85<br>
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> ------------------------------------------------------------<br>
><br>
><br>
> On Wed, Sep 1, 2021 at 1:56 PM Alan Suc <<a href="mailto:suc.eleve@ecole-navale.fr" target="_blank">suc.eleve@ecole-navale.fr</a>> wrote:<br>
><br>
>> Sir,<br>
>><br>
>> Thank you for your answer. I tried yours first but it didn't work, while M<br>
>> Sakr's one worked, which is quite strange as I reinstalled MobilityDB last<br>
>> week so I guess I should have the most recent version. An other question,<br>
>> I'm using dwithin() and |=|but those fonctions seems to don't work. Indeed,<br>
>> for the dectection of near miss situation between ships I use dwithin to<br>
>> detect ships who came closer than 1000m to the one studied, but this<br>
>> function seems to don't work as it also select ships which were at dozens<br>
>> of kilometers. Also |=| seems lost as it returns a distance of 0.53 m at<br>
>> closest point of approach while QGIS measures 59km for the same line. I<br>
>> join a screen capture which, I guess, is more more explicit.<br>
>><br>
>> Best Regards,<br>
>><br>
>> A. Suc<br>
>><br>
>> Le 31/08/2021 à 18:28, Esteban Zimanyi a écrit :<br>
>><br>
>> Please find enclosed a new version of the function since the suffixes for<br>
>> the subtypes in MobilityDB have been changed to _inst, _instset, _seq, and<br>
>> _seqset for better readability. Usage examples of the function are also<br>
>> included in the file.<br>
>><br>
>> On Tue, Aug 31, 2021 at 4:53 PM Mahmoud SAKR <<a href="mailto:mahmoud.sakr@ulb.ac.be" target="_blank">mahmoud.sakr@ulb.ac.be</a>><br>
>> wrote:<br>
>><br>
>>> [...]<br>
>>><br>
>><br>
>><br>
>>> I understand that you got a sequence of (location, timestamp) pairs, from<br>
>>> which you want to construct a trajectory. But you want to split into<br>
>>> multiple trajectories whenever there is a big gap (in time or in distance)<br>
>>> between two consecutive points.<br>
>>><br>
>>> Enclosed is an SQL function to do this.<br>
>>><br>
>><br>
<br>
<br>
</blockquote></div></div>