Traffic updates do not support floats

[danielfdsilva]

An error is thrown when edge_speed_in_km_h is a float, however float values are allowed through the profile file with forward_speed, backward_speed.

[info] Input file: /data/.tmp/osrm/roadnetwork.osrm
[info] Threads: 4
[info] Reading node weights.
[info] Done reading node weights.
[info] Loading edge-expanded graph representation
TBB Warning: Exact exception propagation is requested by application but the linked library is built without support for it
terminate called after throwing an instance of 'osrm::util::exception'
  what():  CSV file /data/.tmp/speed-upgrade-561634.csv malformed on line 1:
 561635,561636,2.5
include/updater/csv_file_parser.hpp:120include/updater/csv_file_parser.hpp:85

[TheMarex]

Do you think floating point precision is important for your use-case or would routing fix this?

[danielfdsilva]

@TheMarex Yes, the precision is important. We're using OSRM in a sort of unconventional way and it makes a difference. I tried to multiply the value by say 1000, so we could discard the decimals, but that gives weird results and the routes picked change. (Any idea why this happens? Is there any speed limit set internally?)
What would your suggestion be regarding routing?

[TheMarex]

What you could try is to change https://github.com/Project-OSRM/osrm-backend/blob/master/include/updater/source.hpp#L53 to double instead of unsigned. I think that should "just" work.

[oxidase]

also a CSV line grammar at https://github.com/Project-OSRM/osrm-backend/blob/master/src/updater/csv_source.cpp#L40 must be changed to

qi::double_ >> -(',' >> (qi::double_ | qi::attr(value_if_blank))));

[danielfdsilva]

This seems to be working. It is not throwing errors anymore. Thanks @TheMarex @oxidase.
Any chance this will make it into a release soon?

[danpat]

@danielfdsilva one reason why simply multiplying by 1000 might not work is because of the other weights associated with the graph - primarily turn costs. Unless you've made extensive changes to the .lua script to disable all these other weighting parts, route selection will not be purely based on your speed data import.

Also note that interanlly, OSRM precision is limited - we only store 0.1 second resolution on any road edge, and 0.1 resolution for turn costs. This is one of the reasons that @TheMarex wondered why decimal precision on speeds matters - OSRM may already not store sufficient precision for your use.

[danielfdsilva]

@danpat I did heavily modify the lua file, stripping it of almost everything. Ours is a very specific use case, that's why we've these needs.
I checked the docs again and increased the max_speed_for_map_matching and weight_precision. This, together with the floating speeds seems to have done the trick for me.