[OSM-talk] Canals

[Ben Robbins]

Its double the width if not more, but its more inportant that the thin bit 
is thin, than the wide bit is wide.  I was thinking of doing exactly that 
(natural-water) but that would then mean having the defautl canal thin, and 
haveing the additonal area where wider.  But 90% of the canal is wider.  So 
a lot of effert.

I had an idea:  What about having tags stating the width specifically to 
canals.  so Canal_width=xyz will then render additonally to the canal.  If 
the outlines of waterway=canal and the additonal area are rendered togehter, 
and then the water is rendereed ontop, then the wider bits will blend.   
This leaves the problem of 1.  Having 'laybye' style sections, although the 
rarety of these may mean areas are enough, and 2.  The outline going between 
the 2 thicknesses may be incorrect.  I.e. the canal I'm currently mapping 
when from thin to thick with a 45'degree angle.  This would require it to 
render to a spike.  If its 90' or rounded, then then thats not a problem.

" is it really necessary?"  Well, I think so.  Why be less acurate than 
posible?.  Even if one person choices not to add this, its inportant with 
all options to allow people to do more acurate maps if they want.

Ben




From: "David Earl" <david at frankieandshadow.com>
To: "Ben Robbins" <ben_robbins_ at hotmail.com>
Subject: RE: [OSM-talk] Canals
Date: Mon, 6 Nov 2006 19:36:47 -0000

Unless it is very much wider, is it really necessary?

But one thing I did where our river had a weir which spills in to a pond
before resuming the river course again is make a 'natural=water' area to
represent the wider pond bit. It renders pretty well - it looks obviously
part of the water course.

David

 > -----Original Message-----
 > From: talk-bounces at openstreetmap.org
 > [mailto:talk-bounces at openstreetmap.org]On Behalf Of Ben Robbins
 > Sent: 06 November 2006 19:27
 > To: talk at openstreetmap.org
 > Subject: [OSM-talk] Canals
 >
 >
 > The width of Canals varies around locks, (and also in other
 > places I would
 > imagin), but around locks in particular.  It gets thinner by
 > about half the
 > size.   How should I go about makeing this?   If i have the way
 > as a canal,
 > and then use areas to make the wider bits wider, then 90% of the
 > canal will
 > be area, as the average section is widest.  On the other hand, if
 > I make 2
 > tags, for the 2 thicknesses, or have an additonal canal_width
 > tag, then this
 > would render symetrically and get wider and thinner in steps.  Commonly
 > canals do do this, although usually the steps are diagonal, and commenly
 > they are not symetrical.
[snip]

_________________________________________________________________
The new Windows Live Toolbar helps you guard against viruses 
http://toolbar.live.com/?mkt=en-gb