[OSM-talk] Getting highway refs onto the mapnik slippy map layer

[Richard Fairhurst]

Dave Stubbs wrote:

> On 05/10/2007, Sven Grüner <sven at schunterscouts.de> wrote:
>> Tom Chance schrieb:
>>> Look at London at zoom level 10 and imagine every red road having  
>>> a label, it
>>> would be impossible to read:
>>> http://www.openstreetmap.org/?lat=51.5024&lon=-0.1107&zoom=10
>>
>> Yes, you're right about that.
>>
>> But the London example showed me that it would be good to blend  
>> out not
>> only the labels of minor roads but the roads itself. When I look  
>> at that
>> link I expect the M25 to pop right into my eyes, maybe also the most
>> important trunks. But that dense mesh of primaries and secondaries is
>> only confusing.
>
> The washed out road colours don't help this much...
>
> If you look at google's effort you can see what it would look like
> with trunk labels at zoom 10 with more defined colours.

Comparing the OSM example above to the equivalent on Google (http:// 
maps.google.co.uk/? 
ie=UTF8&ll=51.513016,-0.10231&spn=0.436722,1.19751&z=10&om=1), OSM's  
map is IMO much more useful.

OSM prioritises suburb names over road numbers. This is sensible at  
that scale. It's more helpful to know where (say) Hammersmith and  
Hendon are, than that some indistinguishable road somewhere in the  
centre of London is the A4200.

On the Google example, the decision on which roads to label is being  
made entirely by a placement algorithm, which is insane. It's not  
even as if it's a very good algorithm - the A406 and A205 (North/ 
South Circulars) deserve to be labelled frequently all the way  
around, but in fact they each have just two isolated labels.

On the OSM stylesheet, it may be sensible to make the green (trunk)  
and blue (motorway) a _bit_ stronger and thicker - I'll defer to  
Steve Chilton on that one - but certainly not the red; red is a very  
dominant colour and has a tendency to look like the most important  
road on any given map. The other issue is casing, which Google uses  
at this scale and OSM currently doesn't (largely correctly, I think:  
again there might be a case for it on the motorways).

As a general issue of style, Google have unashamedly adopted a  
"streetmap" style, and all their other data is utterly subservient to  
this. We have, I think, a more balanced approach that reflects the  
greater richness of our data. I would be a little ethically unsettled  
if we were to adopt a Google-like rendering which removed railways to  
gain greater importance for roads!

cheers
Richard