Hi Sam and all I'm wondering if the best tiling is a fixed number of tiles (5X5) or if it should be defined as a maximum size of some type for a tile.
Using JOSM/Canvec files, I worked in high density urban areas where a 4X8 tiling was almost insufficient. For some rural areas, a 2X2 tiling was just fine. A 5X5 tiling for Canvec is just an averaging of needed tiling value! Knowing an optimal size value for default JOSM configuration, we could tile any type of data using a Quadtree algorithm http://en.wikipedia.org/wiki/Quadtree Let suppose the optimal tile size is 2M (the initial tile is the file) For each tile: Is processed tile size < 2M? Yes: then there is no need for sub-tiling - stop processing the tile No : Split the processed tile 2X2 then repeat the process You would end up with 1, 4, 12, 16 ... tiles having a file size < 2M with some of the tiles covering 1/48, other 1/4 of the processed area! Using Canvec data, I would be surprised that tiling needs to go deeper than 8 levels (1/48) for some of the tile. What would be this optimal size for JOSM? Kilobytes, nodes, feature? I don't know! Even the number of members in Relation seems to affect JOSM. If we can find some hard facts to define it, this could be implemented as the tiling algorithm. Cheers, Daniel (-Xmx256M) -----Original Message----- From: talk-ca-boun...@openstreetmap.org [mailto:talk-ca-boun...@openstreetmap.org] On Behalf Of Sam Vekemans Sent: March 28, 2010 12:26 To: impo...@openstreetmap.org; Talk-CA OpenStreetMap Subject: [Talk-ca] Canvec tile splitter 999x33 a to y 5x5 and/or put on adedicated API? Hi all, We are getting more progress on Vancouver Island, thanks to (haitelk) who has just added in more wooded area. And the new CVRD data is in the planning, discussing & sorting data phase. :-) What we still need todo is make a tool that will automatically slice the NTS tiles (canvec .osm files) into 25 pieces, so then a local area mapper can easly take 1 square at a time & work with it, choosing the data that they need to add in. I think that OSmosis has this ability, has anyone varified this? This will be of great help to everyone, as we are also using the Toporama WMS layer to be tracing & using it for reference. Otherwise, if we dont have the 1/25th tile area, its harder to ensure that no 'bulk_implopping' happens where the user gets lazy and doesnt bother to check the area 1st. Since the 1/25th tile size is a standard JOSM working space, we would (just about all of the time), have only 1 mapper is working at a time. (even in the big cities, this size is managable). Oh, this whole CanVec dataset would be great to host on a different API, (like i talked about on my last message for OpenImportsMap does anyone know if perhaps the devAPI would be a good place for it? Or should we make a new one that is dedicated to wholesale imports? Thanks, Sam -- Twitter: @Acrosscanada Blogs: http://acrosscanadatrails.posterous.com/ http://Acrosscanadatrails.blogspot.com Facebook: http://www.facebook.com/sam.vekemans Skype: samvekemans OpenStreetMap IRC: http://irc.openstreetmap.org @Acrosscanadatrails _______________________________________________ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca _______________________________________________ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca