[OSM-talk] LU overlay idea

[Artem Pavlenko]

On 29 May 2007, at 00:08, Robert (Jamie) Munro wrote:

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> Artem Pavlenko wrote:
>> Hello everyone,
>>
>> There was an idea to put LU on a separate layer (overlay) . I have
>> created a simple demo, just see how this might look like:
>>
>> http://media.mapnik.org/osm-tube.html
>
> Cool! Some thoughts:
>
> A small bug: Where two lines run together (district and circle  
> lines for
> example) currently one completely covers the other. They need to  
> run in
> parallel.


Not sure what the best way to address this. We can have multi colored  
stripy strokes or we can parallel (displaced) lines.

>
> Can we only show tube lines on the main map if they are not in a  
> tunnel,
> or is the data for that not in the database yet?

I'll need to check.
>
> It might be nice to be able to model tube stations as small ways  
> linking
> tube lines, so that we can make an effect like the multiple-blob big
> stations on the tube map, rather than make them all just circles.
> Perhaps we could add the non-blob stations as non-blobs as well, and
> maybe even then the "disabled access to platforms" style blobs where
> applicable (although I think they need a better symbol).

Yes we could try.
> On the "tube lines aren't in their real locations front", I think that
> we should put them in the right place where we know what that is,  
> but if
> we don't know, it doesn't matter, just put them somewhere that  
> looks right.
>
> If some tube geek later comes along and says "That tube line is in the
> wrong position", we say "Thank you very much for telling us. Please
> click the edit tab and move it to the right position", but there is no
> need to go to extraordinary efforts now to research those positions.
>
Good ideas!
> Finally, can openlayers only offer the "tube" overlay if you are
> browsing somewhere near London and zoomed in a bit? It would be really
> silly if when browsing places with no mass transit for miles if the
> server has to serve lots of empty transparent tiles, and when you  
> click
> the dropdown you get options that are never going to make any
> difference. This obviously becomes much more significant if we start
> adding more layers that are only interesting to other parts of the
> world. The other option, of course, is for all underground railway and
> tram systems globally to share a layer. But most of the world doesn't
> have either, and other layers we may develop in future may only be
> relevant outside cities etc.
>

I'm not sure OL can do this. It looks like it should be done at JS  
level but without reloading the whole page.
AJAX ? It is certainly an important feature for multi layered  
regional maps.

Thanks for your comments.

Cheers
Artem

> Robert (Jamie) Munro
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Artem Pavlenko
http://mapnik.org



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