<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">OSM uses the following scaling factor:<div><a href="http://trac.openstreetmap.org/browser/sites/rails_port_branches/api06/lib/geo_record.rb#L2">http://trac.openstreetmap.org/browser/sites/rails_port_branches/api06/lib/geo_record.rb#L2</a></div><div><span class="Apple-style-span" style="font-family: Times; font-size: 16px; "><span class="Apple-style-span" style="font-family: verdana; font-size: 13px; "><table class="code" style="border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; border-top-width: 0px; border-top-style: initial; border-top-color: initial; empty-cells: show; font-size: 12px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; margin-top: 0px; margin-right: auto; margin-bottom: 0px; margin-left: auto; table-layout: fixed; line-height: 15px; width: 1244px; "><tbody><tr><td style="background-image: initial; background-repeat: initial; background-attachment: initial; -webkit-background-clip: initial; -webkit-background-origin: initial; background-color: rgb(255, 255, 255); font: normal normal normal 11px/normal monospace; overflow-x: hidden; overflow-y: hidden; padding-top: 1px; padding-right: 2px; padding-bottom: 1px; padding-left: 2px; vertical-align: top; background-position: initial initial; "> SCALE = 10000000</td></tr><tr></tr></tbody></table><br></span></span><div><div>Shaun</div><div><br></div><div>On 12 Nov 2008, at 05:08, Marcus Wolschon wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Hello Robert,<br><br>as far as I understand it the OSM-databases store the location<br>in long integers anyway. Thus there is no precision to be gained<br>from using floats. You only loose storage-space, computation-time<br>and native functionality on platforms that do not have native floating-<br>points (like many cellphones, reflashed navigation-devices or<br>all mobile J2ME java-platforms).<br><br>Marcus<br><br>2008/11/12, Robert (Jamie) Munro <<a href="mailto:rjmunro@arjam.net">rjmunro@arjam.net</a>>:<br><blockquote type="cite">Floats only allow more precision as the location being considered tends<br></blockquote><blockquote type="cite">towards 0,0 latitude and longitude. For the general case, using an<br></blockquote><blockquote type="cite">integer with the same number of bits of storage will always be more<br></blockquote><blockquote type="cite">precise, particularly at the extremes.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">As others have said, 32 bits gives errors of less than 10mm on the<br></blockquote><blockquote type="cite">equator, with even greater accuracy as you move away from it. This is<br></blockquote><blockquote type="cite">around 1000 times more accurate than the data in OSM can be reasonably<br></blockquote><blockquote type="cite">recorded at with standard GPS equipment.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Robert (Jamie) Munro<br></blockquote><br>_______________________________________________<br>dev mailing list<br><a href="mailto:dev@openstreetmap.org">dev@openstreetmap.org</a><br>http://lists.openstreetmap.org/listinfo/dev<br></div></blockquote></div><br></div></body></html>