Hi François, No, we likely won't change the storage precision any time soon. OpenStreetMap itself only stores
Here is the constant that OSRM uses to store lon/lat decimal values in integer format: https://github.com/Project-OSRM/osrm-backend/blob/master/include/util/coordinate.hpp#L44 We multiply the lon/lat decimal by 1e6 (1000000), then store just the integer part. This is equivalent to about 10cm precision at the equator. *HOWEVER* you can't just change this without also updating the coordinate vector packing. It's not a simple change. OpenStreetmap stores 1 additional decimal place, in the same way (database stores integers). Here are the code references. https://github.com/openstreetmap/openstreetmap-website/blob/master/db/structure.sql#L353-L354 https://github.com/openstreetmap/openstreetmap-website/blob/396f2e28dd27d514f7882c3918103b12764038de/lib/geo_record.rb#L17-L20 Increasing OSRM's storage to match OSM would require more memory usage, and little obvious gain. daniel On Fri, Mar 2, 2018 at 2:57 AM, François Lacombe <fl.infosrese...@gmail.com> wrote: > 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 <dan...@mapbox.com>: > >> 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 < >> fl.infosrese...@gmail.com> 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 >>> OSRM-talk@openstreetmap.org >>> https://lists.openstreetmap.org/listinfo/osrm-talk >>> >>> >> >> _______________________________________________ >> OSRM-talk mailing list >> OSRM-talk@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/osrm-talk >> >> > > _______________________________________________ > OSRM-talk mailing list > OSRM-talk@openstreetmap.org > https://lists.openstreetmap.org/listinfo/osrm-talk > >
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