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#1 2015-04-17 08:43:58

Seehundefuehrer
Member
Registered: 2015-04-17
Posts: 2

Orientation of inshore seamarks / signs in the online map

Hi,

I'm a little bit confused about the :orientation - tag, for example seamark:notice:orientation. I'm member of a water-rescue unit in Aschaffenburg, Germany and we're using the OpenSeaMap for orientation. When I look on  map.openseamap.org I see that all the signs which have an :orientation - tag are turned by 180°. (see the two waterski-signs on http://map.openseamap.org/?zoom=16&lat= … F0TFFTFTFF, they normally should point at each other and not away from each other)

When I take a look in the Wiki under http://wiki.openstreetmap.org/wiki/Open … tice_Marks, I can read:

orientation    The angular distance measured from true north to the major axis of the object.

IMHO I would say a sign which faces directly to north should be tagged with :orientation=0 and should be displayed on the map upside down. In fact on map.openseamap.org a sign with :orientation=0 isn't displayed upside down, it is displayed top up and bottom down.

So something seems to be wrong here, the definition for :orientation or the rendering on the map.


Greetings
Mirko

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#2 2015-04-17 09:23:50

malcolmh
Member
From: Hull, UK
Registered: 2012-09-05
Posts: 194

Re: Orientation of inshore seamarks / signs in the online map

Mirko,

The orientation of a sign is like light sector bearings: it is a bearing-to, not a bearing-from. So a sign with orientation=0 is visible to an observer looking north & hence the painted side of the sign faces south. If you look at the signs on the bridge just downstream from your example, you will see that the no_passage signs are correctly oriented with respect to the navigation, as confirmed by the positions of the channel_one_way signs.

One error I see in the editing of some of those signs, is that orientation values have been changed to zero. The entire orientation tag should have been deleted, rather than leave a falsely valued tag.


Malcolm Herring, Developer

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#3 2015-04-17 15:54:36

Seehundefuehrer
Member
Registered: 2015-04-17
Posts: 2

Re: Orientation of inshore seamarks / signs in the online map

Hi Malcolm, thanks for your answer.

So, the definition and the display on the map is correct, my thoughts (and the thoughts of the guy who imported the seamarks for the river Main) were wrong smile

Now I've found some Work to do "turning" all the signs in my Area to the right direction... :-/

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