{"comment":{"created_at":"2011-10-11T08:01:23Z","body":"[springmeyer] As part of a larger effort to review the tickets at http://trac.mapnik.org/wiki/BoundsClipping I have integrated this approach of first trying to forward the map bbox into the layer srs, then falling back to the original approach of layer back projected into the map srs. Applied in r2784, and will therefore close this ticket. Thanks to frederik for the initial patch and for the other contributions by olt and wohnout.\r\n\r\nNote: this fallback should be now rarely needed if the user can supply a 'maximum-extent' for the map in the coords of the map srs.  See #506 for more detail. But, a more robust, automatic method is provided in olt's revised patch, which I have finally gotten around to testing. I've moved this portion of the patch (which I did not apply) to a new ticket here: #751, because I feel like it warrants more discussion. Notably it can lead to a significant performance hit for multi-threaded servers. This is not the fault of the patch by rather that proj4 locks for each transform (even if you compile against proj4 trunk and the mapnik mutexes are not used proj4 still locks internally). In tests using paleoserver with 2 threads and proj 4.7 (so using mapniks internal locks) the impact of using 16 points for bbox transformation was 10 r/s (so a tile that could be served at ~30 r/s using the normal 2 point/corner projection and a 'maximum-extent' value dropped to < 20 r/s with the 16 point projection).","updated_at":"2011-10-11T08:01:23Z","url":"https://api.github.com/repos/mapnik-org/mapnik/issues/comments/2358104","id":2358104,"user":{"avatar_url":"https://secure.gravatar.com/avatar/941f68386168a8a6b60f2529a7830af7?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-140.png","url":"https://api.github.com/users/artemp","id":59056,"login":"artemp"}},"action":"created","issue":{"number":547,"created_at":"2011-10-11T08:01:17Z","pull_request":{"diff_url":null,"patch_url":null,"html_url":null},"body":"see: http://www.mail-archive.com/mapnik-devel@lists.berlios.de/msg00674.html, BoundsClipping, and #548","comments":8,"title":"Problem with local projections and worldwide data extent","updated_at":"2011-10-11T08:01:23Z","url":"https://api.github.com/repos/mapnik-org/mapnik/issues/547","id":1872178,"assignee":null,"milestone":null,"closed_at":"2011-10-11T08:01:23Z","user":{"avatar_url":"https://secure.gravatar.com/avatar/941f68386168a8a6b60f2529a7830af7?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-140.png","url":"https://api.github.com/users/artemp","id":59056,"login":"artemp"},"html_url":"https://github.com/mapnik-org/mapnik/issues/547","labels":[{"name":"Core_Library","url":"https://api.github.com/repos/mapnik-org/mapnik/labels/Core_Library","color":"FFFFFF"}],"state":"closed"},"legacy":{"issue_id":1872178,"comment_id":2358104}}