Date: Mon, 7 Jan 2019 21:23:18 +0700
From: Mishari Muqbil <[hidden email]>
To: [hidden email] Some people from the Thai mapping community are meeting Ajay, the mapping
lead from Grab to discuss the quality issues we've been having with their
mappers but before we do this I wanted input from the wider community.
1. What's a fair expectation from such a mapping team? On one hand there's
the potential to add much geometry to the project, on the other hand any
bad data has an outsized effect on utility and perceived quality. What's
the sweet spot? Sadly Bicycle routing in the Grab mapped areas in Bangkok
using Brouter.de is now unreliable because service roads have been added
without information about access permission or barrier and in other cases
ways have been connected where no connection exists.
I only can comment on the cycling aspects.
I fear that we can expect major problems for bicycle routing when a company that operates motorized taxies does the mapping. There is a basic conflict of interest: The motorized-taxi driver is only interested in information that regards his type of vehicle, whereas a person on a cycle needs much better information in order to be able to take advantage of this means of transpart, i. e. many more routes are open to bicycles than to cars, when the map has the necessary additional information.
When I started with OSM locally in my area (Veneto, Northern Italy) many minor roads had been mapped rapidly by one single user by armchair mapping, and when I started with using the map for bicycle tours (using bicycle routing) I kept encountering large numbers of errors, mostly in two categories: false positives because of physical barriers invisible on aerial photos, and, many more, false negatives i.e. minor ways between buildings that would accommodate bicycles, but were missing on the map. Essentially the amount of work needed to obtain a good map for bicycles is considerably higher than for a map that will only be used for car routing. Mapping for bicycles requires more details, like minor roads that can
onluy be used by pedestrians or bicycles with accurate width plus
mapping of all obstacles, including the maxwidth of all barriers.
The false negatives can only be eliminated by survey and/or arm-chair mapping using street-level photography (in my case Mapillary) on bicycle.
I would imagine that this basic issue is present even more in SE Asian countries.
I have no solution to propose, I can only confirm from my own experience that this is a real problem.
> On 7. Jan 2019, at 18:53, Volker Schmidt <[hidden email]> wrote:
> Essentially the amount of work needed to obtain a good map for bicycles is considerably higher than for a map that will only be used for car routing. Mapping for bicycles requires more details, like minor roads that can onluy be used by pedestrians or bicycles with accurate width plus mapping of all obstacles, including the maxwidth of all barriers.
+1, I would also expect cyclists to be more demanding, a 5km detour because of a missing connection will maybe not even be noticed by a car driver, but a cyclist will be very upset when she sees it ;-)