[mkgmap-dev] Why do we render place=island polygons in the default style?

Sun Jul 24 08:53:36 BST 2016

Hi all,

we came accross this in this discussion :

http://gis.19327.n5.nabble.com/Option-to-output-polygons-in-size-order-tp5878989p5879007.html

The polygons file contains these two rules:

place=island & name=* [0x53 resolution 19]

place=islet & name=* [0x53 resolution 20]

I assume they were added to "catch" small islands within lakes,

but they are producing really large and complex polygons

for islands like the monster mp-relation 6038068<https://www.openstreetmap.org/relation/>

which covers the mainland of the UK.

According to GPS MapEdit the polygon type 0x53 seems to stand for

"Sandbank, tidal/mud flat", which might be good for very small

islands/islets, but makes no sense for really large islands.

What would be missing without the 1st rule, esp. when precompied

sea data is also used?

I can think of adding more clauses, e.g.

place=island & name=*  & natural!=coastline ...

place=island & name=* & area_size()  <= 100000 ...

Any thoughts?

Gerd

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