[OSM-talk] Big Lakes

Bernhard R. Fischer bf at abenteuerland.at
Thu Feb 19 06:49:57 UTC 2015


On Wednesday 18 February 2015 15:29:28 malenki wrote:
> colliar wrote:
> >Am 18.02.2015 um 14:48 schrieb malenki:
> >> Jochen Topf wrote:
> >>> Please do not add more (and more difficult cases like lakes on
> >>> islands in lakes on land) to the data, otherwise this process will
> >>> get more brittle than it already is.
> >> 
> >> Well, that is a word.
> >> 
> >> What do you think of the Great Lakes mapped (partly) both with
> >> coastline and MPs?
> >
> >-1
> >
> >We already have problems with the update cycle differences of the
> >coastline and the rest of the map. Would would not gain much and simply
> >move the decision over to the renderer. Dual-Systems are confusing and
> >lead to further divergence.
> 
> IMHO this is clear. I hope(d) for a recommendation what to keep and what
> to drop.
> 

To define a specific direction for the ways (like it is defined for the 
coastline) is the only way to resolve this problem for all cases in a long 
term.
The renderer can then algorithmically decide what is lake and what is land and 
we do not depend neither on the map editors' mapping strategies nor on those 
relations to define inner/outer/... which are only necessary because of the 
missing direction definition.

Best regards,
Bernhard


PS: I'm dealing with rendering since a long time, specifically with sea charts 
where depth contours with different fill colors are shown. And because there 
is no limit in how many shallow/deep water areas are within other shallow/deep 
water areas in the real world, the solution was to define a direction so that 
the renderer can decide on which side of a way is the deep/shallow water. See 
this example: https://www.cypherpunk.at/download/smrender/samples/murter.pdf

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