[OSM-talk] Canals

[Ben Robbins]

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.

Also Docking areas, and fishing areas may be permitted, or not on only one 
side of the river, and they may also be an area.  If this area is the left 
hand side of the canal, and the canal is the common width, then this area 
would need to be part of the segment, wich is inposible. (Due to the 1 
dimentional'ness of a segment!)

Any suggestions?

2 options that I havnt thourght over too much are: 1) Have different tags 
wich will render with different ends.  Having rounded/pointed/flat ends will 
allow a combination of shapes to be created. or 2) When you tag something as 
waterway=canal, josm automatically creates 2 parrellel lines from this and 
you then create an area, wich can be manipulated accordingly.  (Asuming Imi 
coded it of corse!).

Thanks

Ben

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