[mkgmap-dev] Re: [PATCH v1] Re: maxspeed tag vs road_speed preset

Thu May 21 19:17:46 BST 2009

No hardcoding speeds would be awful. Not everyone wants to have OSM maps 
for carrouting (commercial alternatives are not very expensive and still 
much in advance), for cycling, biking, hiking however alternatives are 
much more expensive and not allways better. hardcoding will not work. I 
have since quite some time deleted those maxspeed lines out of the 
source because it would really mess up routing for bicycles and mtbikers.

The best would be to have a switch that deactivates all carrelated 
settings (there are some more). For bicycle use to get good routing you 
need to switch quite a lot of things (i.e. delete all motorcar=no, then 
set bicycle=no to motorcar=no), delete maxspeed, and give high 
road_class and road_speed to footways, else they will not be chosen when 
autorouting. Then on the other hand degrade ways that have 
sac_scale=alpine_hiking or higher (just as expample, rules depend on 
user preferences).

So there is quite a lot to be setup. Being able to set this in the 
style-file without needing to patch and delete rules in the sources 
would make it much easier. I.e. for cycling turn restrictions - I would 
only keep them for primary and secondary roads, maybe on tertiary roads. 
On residential streets turn restrictions would usually only apply to cars.

and so the list goes on.

The most important IMHO is to read the whole style-file from top to 
bottom, and only apply rules to what follows below.
If you are afraid the style-file gets too complex, maybe define a second 
file in which one can find centralised all hardcoded behaviour of now, 
easy to change (editing styled.converter is pretty advanced).

Toby Speight wrote:
> 0> In article <212454.24051.qm at web28515.mail.ukl.yahoo.com>,
> 0> Marco Certelli <URL:mailto:marco_certelli at yahoo.it> ("Marco") wrote:
>
> Marco> 1st: I do not know very well how to keep the answer in the same
> Marco> thread...
>
> Just follow-up in the normal way (sometimes called "group reply" or
> "reply to all"), then remove the original sender from the recipients (so
> that you don't annoy them by sending two copies).
>
>
> Marco> I can speed on a city road at 60 km/h during night and 15 km/h
> Marco> during day. ... And of course I can just imagine the endless
> Marco> discussions for each road about the right value to give to an
> Marco> "average_speed" tag... Much better would be to automatically
> Marco> calculate an average_speed tag by using all information the OSM
> Marco> DB already have: the highway type, the maxspeed tag, the number
> Marco> of crosses per kilometer, the curves (radius and frequency) and
> Marco> also the available GPX real speed data.
>
> Yes - IIRC there is a Summer of Code project to collect and use gathered
> speed data from GPS tracks to give realistic speed estimates.  But the Garmin
> maps don't (as far as we know!) have any provision for time-dependent speeds.
> So it's always going to be a very rough estimate.  Let's not get too
> worked up about these details yet!
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