[Talk-us] NHD Hydro Connectors

[Phil! Gold]

* David Fawcett <david.fawcett at gmail.com> [2011-02-18 10:13 -0600]:
> In some areas where the National Hydrography Dataset (NHD) has been
> imported, the rendering of the data is less than desirable.  I am not
> sure if this is something that should be fixed in renderers or in the
> data.

IMHO, it's a rendering issue.  First off, it also affects the current best
practice (as I understand it) of mapping wider waterways as riverbank plus
linear way; if the linear way is tagged waterway=stream, you get the same
artifacts.

Secondly, it is often the case that waterways are considered to continue
through bodies of water, which would indicate the necessity of the
connecting linear ways to accurately reflect local naming of water
features.  I know of several places in my area where a river was dammed to
form a lake, the lake is known as "Such-and-such Reservoir", but the
original river is still considered to be running through the middle of the
reservoir and shows a such on maps.

Thirdly, having a complete waterway network is a potentially useful thing
(for many of the reasons the NHD adds the connecting ways in the first
place) so their presence shouldn't be discouraged.

My conclusion is just that the renderers need to handle linear streams on
top of water areas (natural=water or waterway=riverbank) better and no
tagging changes should be needed.  Submitting a patch for this is on my
list of things I plan to look at eventually if no one beats me to it, but
that's a long list with other things ahead of stream rendering.

-- 
...computer contrarian of the first order... / http://aperiodic.net/phil/
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