[OSM-talk] cadastre, ways, rendering

[Florian Loitsch]

On Tuesday 23 January 2007 16:33, Marcus Bauer wrote:
[SKIP]
> To avoid this you either add more and more rules to the renderer, ad
> infinitum, or you help it a bit. You don't loose any information if only
> one side of a motorway has a ref=A5 key/value.
Actually you do. How should a routing algorithm get the information? How is it 
supposed to know, that both ways are related?
>
> If a highway has more than one ref, like A8/E88, it makes sense to
> alternatingly tag ways, i.e. one section of a highway A8, the next E88.
> You will always have more information to put into the map, but it
> doesn't get better and isn't even of use for later routing, as long as
> it is tagged motorway.
I disagree.
Take the following example:
http://www.viamichelin.com/viamichelin/int/dyn/controller/ItiWGPerformPage?reinit=1&strStartCityCountry=1424&strStartAddress=222+route+des+dolines&strStartCP=06560&strStartCity=Valbonne&strDestCityCountry=1424&strDestAddress=&strDestCP=06000&strDestCity=Nice&image2.x=59&image2.y=2
The routing algorithm nicely describes all roads you'll have to traverse to 
get to your target. If you alternate the sections of your highway the routing 
algorithm might give you several steps instead of one. Something like:
- step4: on A8 100m
- step5: on E80 200m
- step6: on A8 220m
...

>
>
> Another example: how do you make curves? Actually you add points until
> it nicly renders at higher zoom levels. So in a certain way you "change"
> data to suit the renderer.
It would be nice to avoid that too. My TOMTOM sometimes tells me to take a 
sharp turn on the left/right. IMHO they interpolate nodes, and only if the 
direction change is too big, they annotate it. This way the renderer can 
interpolate ways, but is still able to render sharp turns too.

>
> The point is to find a good compromise.
I agree. But we should look at the future. I don't mind if my map is badly 
rendered at the moment if there's enough information in the database, so in 
some future not only are the maps nicely rendered, but the routing algorithm 
works too.
mfg,
// florian
>
> Marcus
>
>
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