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<body class='hmmessage'><div style="text-align: left;">I currently use my own implementation for my java mobile routing and navigation implementation (see we-travel.co.cc), though I would be very happy to switch to a common implementation or help develop such an implementation if this fits my needs.<br>Some rough high level requirements:<br>- data needs to be very compact, but also quickly fetchable<br>- data needs to be devided in manageable, self contained chunks. Some marginal data duplication is needed to keep the correct references.<br>- an index system is needed to quickly find any element in the data (currently about half my total data size are indexes!)<br>- floats are a no-no (many mobile phones don't even know what they are or are extremely poor at handling them)<br>- Data must be ordered,sorted and indexed to allow quick retrieval for display, lookup but also routing purposes. Some trade off need to be made here<br>- To make data is compact as possible, I currently store the coordinates relative to some kind of tile structure. As such, I only need 3 bytes/point.<br>- Node-id's would be nice to have, but are really too much of data if you want to store a full country like Germany on a mobile phone<br>- Most importantly (but most complicated as well) : in countries like the Netherlands, each route section between 2 crossings has his own way id. This is just too much for any routing engine on a mobile phone. I create a new way index based on uniquely interconnected pieces of road with a common set of attributes. I would very much appreciated if this type of logic could be applied on the actual osm data. Anybody else has the same problem ?<br>- Common tags need to be structured in some compact binary encoding (waytypes, roundabouts, oneway, ...)<br>- Must be utf8 compliant<br><br>Great initiative, hope this is going somewhere !<br><br><br></div><br><br><br><hr id="stopSpelling">> Date: Thu, 7 Aug 2008 10:47:55 +0100<br>> From: shaun@shaunmcdonald.me.uk<br>> To: cbro@semperpax.com<br>> CC: dev@openstreetmap.org<br>> Subject: Re: [OSM-dev] Call to mobile developers: OSM binary file format<br>> <br>> Chris Browet wrote:<br>> ><br>> ><br>> > Do you think about floating-point or fixed-point<br>> > coordinates?<br>> ><br>> ><br>> > This is one of the things to discuss. For mobile applications, <br>> > fixed-point is the most efficient but we have to balance this with the <br>> > loss of precision.<br>> Actually the OSM db stores the node's lat and lon as integers. There is <br>> a scaling factor of 10000000 done on the fly when you read and write notes.<br>> http://trac.openstreetmap.org/browser/sites/rails_port/lib/geo_record.rb#L22<br>> <br>> Shaun<br>> <br>> <br>> _______________________________________________<br>> dev mailing list<br>> dev@openstreetmap.org<br>> http://lists.openstreetmap.org/listinfo/dev<br><br /><hr />Ontdek de snelste manier van communiceren! <a href='http://www.startmessenger.be/nl/index.asp' target='_new'>Windows Live Messenger </a></body>
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