<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On 23 Mar 2007, at 17:10, David Groom wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"> <DIV>----- Original Message ----- </DIV> <BLOCKQUOTE dir="ltr" style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> <A title="artem@mapnik.org" href="mailto:artem@mapnik.org">Artem Pavlenko</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A title="reviews@pacific-rim.net" href="mailto:reviews@pacific-rim.net">David Groom</A> </DIV> <DIV style="FONT: 10pt arial"><B>Cc:</B> <A title="talk@openstreetmap.org" href="mailto:talk@openstreetmap.org">talk@openstreetmap.org</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, March 23, 2007 1:48 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [OSM-talk] Slippy map - Mapnik layer UK coastlines</DIV> <DIV><BR></DIV>Hi David, <DIV><BR> <DIV> <DIV>On 23 Mar 2007, at 11:48, David Groom wrote:</DIV><BR class="Apple-interchange-newline"> <BLOCKQUOTE type="cite"> <DIV style="MARGIN: 0px">It seems that the UK coastline is beginning to render better in the Mapnik<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">layer of the slippy map (it's a solid blue fill, rather than the odd shaped<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">grey polygons).</DIV></BLOCKQUOTE> <BLOCKQUOTE type="cite"> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MARGIN: 0px">However it does appear that the source for the coastline might be a rather<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">out of date planet file.</DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MARGIN: 0px">In some places, eg<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px"><A href="http://www.openstreetmap.org/index.html?lat=50.85383936185782&lon=-1.315713476905844&zoom=15">http://www.openstreetmap.org/index.html?lat=50.85383936185782&lon=-1.315713476905844&zoom=15</A><SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">,there is an exact correlation between coastline which is shown in the<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">Mapnik and Osmarender layers.</DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MARGIN: 0px">In other places eg ,<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px"><A href="http://www.openstreetmap.org/index.html?lat=50.81094579389664&lon=-0.09869895092239864&zoom=15">http://www.openstreetmap.org/index.html?lat=50.81094579389664&lon=-0.09869895092239864&zoom=15</A><SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">,the coastline outline in the Osmarender layer seems to be much more recent<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MARGIN: 0px">than the Mapnik layer.</DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV></BLOCKQUOTE> <DIV><BR class="khtml-block-placeholder"></DIV> <DIV>For most of the world I was using original shoreline data, hence it's not as smooth as it should. Polygons are only available for England and Wales, the rest gets blue shoreline lines. To have proper polygons for the whole planet :</DIV> <DIV><BR class="khtml-block-placeholder"></DIV> <DIV>1. We need to agree that storing countries boundaries as polygons is way forward.</DIV> <DIV><BR class="khtml-block-placeholder"></DIV> <DIV>2. We have to decide if storing these polygons in main OSM database is a good idea or not. I personally think it'll be better to store them separately. </DIV> <DIV><BR class="khtml-block-placeholder"></DIV> <DIV>3. Start creating polygons. I have all the tools and I'm happy to help anyone, but it is a big task which requires community participation.</DIV> <DIV> On the other hand, If one person capable of fixing most of the UK coastline it should be peanuts for OSM as a whole. If you want to see nice blue sea and land just do it, don't wait!</DIV> <DIV><BR class="khtml-block-placeholder"></DIV> <DIV> Cheers,</DIV> <DIV>Artem</DIV><BR> <BLOCKQUOTE type="cite"> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"></DIV> <DIV style="MARGIN: 0px">David<SPAN class="Apple-converted-space"> </SPAN></DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV> <DIV style="MARGIN: 0px">_______________________________________________</DIV> <DIV style="MARGIN: 0px">talk mailing list</DIV> <DIV style="MARGIN: 0px"><A href="mailto:talk@openstreetmap.org">talk@openstreetmap.org</A></DIV> <DIV style="MARGIN: 0px"><A href="http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk">http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk</A></DIV> <DIV style="MIN-HEIGHT: 14px; MARGIN: 0px"><BR></DIV></BLOCKQUOTE></DIV><BR> <DIV><SPAN class="Apple-style-span" style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px 0px; -khtml-text-decorations-in-effect: none; -apple-text-size-adjust: auto; orphans: 2; widows: 2"> <DIV>Artem Pavlenko</DIV> <DIV><A href="http://mapnik.org">http://mapnik.org</A></DIV> <DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></DIV></DIV></BLOCKQUOTE><DIV> <BR class="khtml-block-placeholder"></DIV><P>My original query remains, since both areas I was referring to are in the UK, about 70km away from each other.</P></BLOCKQUOTE><DIV>For Southampton area I used coast-line from OSM and Brighton uses original shore-line data. Polygons are tiles by 100x100km. </DIV><BR><BLOCKQUOTE type="cite"><P>I can see advantages and disadvantages to storing polygons in the main OSM database. One disadvantage I guess is it will dramatically increase the amount of data in the database, but I presume it would have the advantage that the polygons can be edited / amended using the usual OSM tools, so that alterations could be made by people with local knowledge</P></BLOCKQUOTE>Agree. But if we want to edit boundaries we need to improve OSM tools to be able to handle geometries such as Polygons, basic topology checks etc. All libraries are out there - JTS for Java and GEOS for c++. And of course data model thingy :) . There is no official way to store Polygons with loops (holes) with current data model AFAIK.</DIV><DIV> <BR><BLOCKQUOTE type="cite"><P>Once 1) & 2) are agreed I'd be happy to assist if I can.</P></BLOCKQUOTE>Me too! </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Cheers</DIV><DIV>Artem</DIV><DIV><BR><BLOCKQUOTE type="cite"><P>David</P><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">talk mailing list</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="mailto:talk@openstreetmap.org">talk@openstreetmap.org</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk">http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk</A></DIV> </BLOCKQUOTE></DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV>Artem Pavlenko</DIV><DIV><A href="http://mapnik.org">http://mapnik.org</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN> </DIV><BR></BODY></HTML>