[OSM-talk] waterway - "routable network" and reservoirs/lakes

Colin Smale colin.smale at xs4all.nl
Tue Jul 28 14:13:17 UTC 2015


Before doing the actual routing, the polygon for the "whole lake" must
be preprocessed in various ways: eliminate areas which are too shallow,
prohibited, one-way/wrong-way, subject to traffic controls etc. Then the
routing algorithm can avoid all these no-go areas, just as if they were
physical obstacles. There is probably an equivalent of "access=private",
"access=permissive" and "access=destination" as well. 


On 2015-07-28 16:03, John Eldredge wrote: 

> In some cases, the navigation path may be different from the named waterway, such as when locks and canals are used to bypass waterfalls or rapids.  In the case of reservoirs and lakes, some areas may be too shallow for navigation, so the actual navigation route may not always be the shortest path between the inlet and outlet points.
> -- 
> John F. Eldredge -- john at jfeldredge.com
> "Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that." -- Martin Luther King, Jr.
> On July 27, 2015 2:25:54 PM Jochen Topf <jochen at remote.org> wrote:
> On Mo, Jul 27, 2015 at 08:08:22 +0100, Lester Caine wrote: On 27/07/15 19:56, Christoph Hormann wrote: In the case where a stream flows into a reservoir , and then a stream (with the same name) also flows out of that reservoir, should a
> linear way be drawn through the reservoir to connect the two streams
> (the reservoir is currently represented by its own closed way tagged
> natural=water, water=reservoir)?

> Yes.

Although a height difference between in and out might indicate a weir or
other obstruction may well indicate that a route is non-navigable? The
outflow from a dam may have the same name, but have no use as a through
This is more about the water flow than about being navigable by a ship.

Jochen Topf  jochen at remote.org  http://www.jochentopf.com/ 

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