[OSM-talk] The Proposed Great Colour Shift

Jóhannes Birgir Jensson joi at betra.is
Thu Aug 20 01:16:33 UTC 2015

For those that did not check on Mateusz Konieczny diary entries[1], 
postings to this mailing list and github discussions then the Proposed 
Great Colour Shift might come as a surprise if it is implemented.

According to the github discussion there is an "overwhelming consensus" 
[2] on moving from current rainbow colour scheme for roads to a 
red-yellow only scheme. I am unsure of where this overwhelming consensus 
formed because I never saw it on this mailing list nor on talk-dev nor 
on announcements, I admit to be an infrequent IRC user but I didn't see 
this overwhelming consensus there and so far no one has been able to 
tell me where it formed or where I can find it.

The design goal seems straight forward, to discontinue green and blue 
for roads and move to red and reddish. For this to happen the decision 
was made to shift current primary, secondary and tertiary colours 
"upwards" so primary is now the colour of secondary and secondary the 
colour of tertiary. Leaving tertiary white.

Tertiary instead gets to be wider than residential and unclassified 
roads, but to be able to spot that you need to have it next to them to 
see which is the wider one.

This one simple change of bleaching tertiary however is something I find 
to be a great hindrance to mapping efforts, particularly in rural areas 
where the roads are isolated and panning over the map, wether in iD or 
using default tiles. Currently it is easy to spot tertiary roads snaking 
through valleys and over vast desert plains, they are yellow and the non 
tertiary roads are white. Tertiary is significant there as it denotes 
the roads between the villages and towns that are often unpaved but 
still the most important, even the only, road. Lesser white colours 
imply the roads not being between larger settlements although they could 
lead to hamlets. The guidelines for mapping in Africa state thus.

Removing the colour from tertiary makes all mapping that much harder to 
verify and quality check. Currently it is easy to see if a tertiary road 
is broken with a white unclassified bridge, not so in the proposed Great 
Colour Shift.

Mateusz has been forthcoming with all changes and done sterling work in 
displaying different areas and how they will look. But he acknowledges 
that this change is not beneficial everywhere on the map and now has a 

"Among potential problems are that it is now harder to recognise road 
type of given road, especially in situation where there is no 
possibility to compare it with other road types.
Such significant change will be confusing for current users of this style.
UK color coding of roads is well known for many people, for them a new 
style - even assuming that it would be intuitive for them - will be less 

The question really arises if this change is beneficial or not for the 
project. Many hours have gone into it and doing CartoCSS on all these 
zoom levels is not trivial. But this is a major shift on the front page 
of our website, a blow to those who use the default tiles through uMap 
or similarly and depend on the UK rainbow road style and makes life 
harder for mappers to visually confirm the type of road.

Should this be a new, alternative style instead?

[1] http://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/35586

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