[mkgmap-dev] [PATCH v2] Move maxspeed calculations to style file

Mon Sep 2 20:24:17 BST 2013

Hi,

Am 01.09.2013 23:29, schrieb Manfred Brenneisen:
> You do a great job, and I really appreciate your work Thinking
> about maxspeed:practical, which can be used to initialize maxspeed
> in some cases, I thought about rural areas, which do not have any
> maxspeed, or maxspeed:practical information included in OSM data:
> The new curviness() function (useful for ways).

Do you mean the practical speed (maxspeed seems to be wrong in my
opinion) in rush hour, rush hour in public holiday, offpeak, inbound
or outbound... ;)

You are right, maxspeed:practical is only useful for one type of vehicle at a certain time, and weather condition. 
That is why it is not in common use, and not approved: http://wiki.openstreetmap.org/wiki/Key%3Amaxspeed%3Apractical
But, today in mkgmap, you don't have a possibility to create your personal maxspeed:practical (or, better call it estimated_speed) from the physical shape of the road. That's why I think about such a function.

maxspeed!=* & maxspeed:practical!=* & curviness()<0.3 { set estimated_speed=120 }
...
maxspeed:practical!=* {set maxspeed=${estimated_speed} }
...
(continue with maxspeed evaluation and way rules)

You are even free to ignore maxspeed:practical, if you don't trust it or don't like it.

The curviness() function itself would not compute a speed value, but a (virtual) numerical value which is made of the physical road shape. And, you are free to let other tags, like surface and width, decrease estimated_speed further. 