Hi Daniel, Thank you for answer I understand well the issue here
Would it be acceptable to specify coordinates storage precision in a next release ? Nevertheless, I got that it won't impact a lot my routing results. All the best François 2018-02-28 20:37 GMT+01:00 Daniel Patterson <[email protected]>: > Hi François, > > What you are seeing is rounding error. > > Internally, OSRM only stores the "duration" of each segment, with a > resolution of 0.1 seconds. On the map, the speed is calculated by taking > the length of the segment, and dividing it by the "duration" value. > > We store longitude/latitude to 6 decimal places, so they have > approximately 10cm precision (https://en.wikipedia.org/ > wiki/Decimal_degrees) depending on your latitude. This precision means > that calculating the length of a segment is limited to +/- approx 10cm > precision as well. > > Both of these precision limits compound for short segments when > displayed on the map, and sometimes the speed values look weird. > > However, they do not affect route selection very much, because routing > is done by accumulating time, and short segments generally only add small > amounts of time to the routing decision. > > daniel > > > > On Wed, Feb 28, 2018 at 10:41 AM, François Lacombe < > [email protected]> wrote: > >> Hi, >> >> While investigating for flaws in a custom profile I'm trying to write, I >> discovered that arbitrary small ways got strange speed regarding the rules >> I used. >> >> Here is an extract from osrm-frontend debug >> https://imgur.com/a/L8coz >> >> All segments on the red line have the same attributes. >> I don't understand why the small parts in the middle got really slower >> speed than the longer ones. >> Do you have any idea? >> >> The purple road with 0km/h speed is normal and expected. >> >> >> Thank you for any hint >> >> Thanks in advance >> >> François >> >> _______________________________________________ >> OSRM-talk mailing list >> [email protected] >> https://lists.openstreetmap.org/listinfo/osrm-talk >> >> > > _______________________________________________ > OSRM-talk mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/osrm-talk > >
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