David<br>I think there are a couple of problems with closing off the ends of the river sections.<br><br>Firstly, purists would argue that a segment crossing the river is an artifice that does not represent anything in the real world.
<br><br>Second, you would need two segments, or the segment needs to belong to two ways (the upstream way and the downstream way). If it belongs to two ways then for one of them it is pointing in the wrong direction. (segment sorting will fix that, but that requires running frollo before Osmarender).
<br><br>I've contemplated doing this myself several times and always managed to persuade myself not to.<br><br>80n<br><br>BTW I noticed an error on the Baghdad map. The al-Sarafiya bridge is still shown, but it was blown up last week ;)
<br><br><div><span class="gmail_quote">On 4/14/07, <b class="gmail_sendername">David Groom</b> <<a href="mailto:reviews@pacific-rim.net">reviews@pacific-rim.net</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff">
<div><font face="Arial" size="2">If the ends of the riverbank were closed off with
segments so the riverbank formed a complete polygon, would the method outlined
below by 80n be enough to render rivers and islands correctly in the mapnik
layer?</font></div><span class="sg">
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">David</font></div></span><div><span class="e" id="q_111ef6cea8e56f2b_2">
<blockquote style="border-left: 2px solid rgb(0, 0, 0); padding-right: 0px; padding-left: 5px; margin-left: 5px; margin-right: 0px;">
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">----- Original Message ----- </div>
<div style="background: rgb(228, 228, 228) none repeat scroll 0% 50%; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial; font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
<b>From:</b>
<a title="80n80n@gmail.com" href="mailto:80n80n@gmail.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">80n</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>To:</b> <a title="reviews@pacific-rim.net" href="mailto:reviews@pacific-rim.net" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
David Groom</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Cc:</b> <a title="talk@openstreetmap.org" href="mailto:talk@openstreetmap.org" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
talk@openstreetmap.org</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Sent:</b> Saturday, April 14, 2007 9:21
AM</div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Subject:</b> Re: [OSM-talk] Islands
</div>
<div><br></div>One method that currently works is to tag islands as part of
the same way as the riverbanks, but make them go anti-clockwise.<br><br>So you
have one way that goes up the left bank of the river for, say, 1km then goes
down the right bank for for the same distance. If the two riverbanks are
imagined to be part of a closed way then the segments should point in a
clockwise direction. Then all of the islands within that 1km section are also
made part of that same way, but tagged in an anti-clockwise direction.
<br><br>This seems to work pretty well, even when cut at arbitrary points by a
bbox, and is understood by SVG so renders with Osmarender. The same
principle also workd for islands in lakes and any other situation where
something has a "hole" in it. <br><br>There are some examples along the River
Thames:<br><br>Simple example: <a href="http://www.informationfreeway.org/?lat=6698535.88756&lon=-57979.86205&zoom=16&layers=B000" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">http://www.informationfreeway.org/?lat=6698535.88756&lon=-57979.86205&zoom=16&layers=B000
</a><br>Complex example: <a href="http://www.informationfreeway.org/?lat=6688981.2611&lon=-51110.08562&zoom=16&layers=B000" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">http://www.informationfreeway.org/?lat=6688981.2611&lon=-51110.08562&zoom=16&layers=B000
</a><br><br>80n<br><br>
<div><span class="gmail_quote">On 4/14/07, <b class="gmail_sendername">David
Groom</b> <<a href="mailto:reviews@pacific-rim.net" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">reviews@pacific-rim.net</a>>
wrote:</span>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff">
<div><font face="Arial" size="2">I don't know :)</font></div>
<div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">I've been meaning to update the large
rivers page [1] to get debate going on the whole large
rivers / lakes idea, which would include a discussion on how to render
islands.</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">Straying away from your initial question, and
looking at large rivers, Osmarender currently renders large rivers, but the
Mapnik layer does not.</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">As I understand it Mapnik needs a proper
polygon to generate the fill and so does not generate a filled wide river
from the proposed rendering on the large rivers
[1] page. </font><font face="Arial" size="2">Own its own this is
fairly easy to implement.</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">Moving now to your question about islands
:</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">It is, as far as I can see, fairly difficult to
intuitively split a river with islands in it into polygons (particularly
where there are many islands close to each other) , where each polygon would
be a continuous way and there is not a complicated system of segments going
between the riverbank and each island. </font> </div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">I'd like to see a modification of my proposal
on the large rivers page [1] where riverbanks would be drawn as a
polygon with a tag something like waterway = riverbank, and islands in these
rivers woul</font><font face="Arial" size="2">d be drawn as waterway =
riverbank; island = yes. Given this suggested rendering, island in
lakes could be tagged exactly the same as islands in rivers and they would
still render correctly.</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">David</font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2">[1] <a href="http://wiki.openstreetmap.org/index.php/Proposed_features/Large_rivers" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">http://wiki.openstreetmap.org/index.php/Proposed_features/Large_rivers
</a></font></div>
<div><font face="Arial" size="2"></font> </div>
<div><font face="Arial" size="2"></font> </div>
<blockquote style="border-left: 2px solid rgb(0, 0, 0); padding-right: 0px; padding-left: 5px; margin-left: 5px; margin-right: 0px;">
<div><span>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">-----
Original Message ----- </div>
<div style="background: rgb(228, 228, 228) none repeat scroll 0% 50%; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial; font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
<b>From:</b>
<a title="lewispusey@earthlink.net" href="mailto:lewispusey@earthlink.net" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">lewispusey</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>To:</b>
<a title="talk@openstreetmap.org" href="mailto:talk@openstreetmap.org" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">talk@openstreetmap.org</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Sent:</b>
Friday, April 13, 2007 5:08 PM</div>
<div style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Subject:</b>
[OSM-talk] Islands</div>
<div><br></div>
<div><font face="Arial" size="2">What is the current best way to draw and tag
islands in rivers and lakes?</font></div>
<div><font face="Arial" size="2">Lewis</font></div></span></div>
<p></p>
<hr>
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