{"id":587,"date":"2023-03-29T12:43:56","date_gmt":"2023-03-29T12:43:56","guid":{"rendered":"http:\/\/blog.geofabrik.de\/?p=587"},"modified":"2023-03-29T12:43:56","modified_gmt":"2023-03-29T12:43:56","slug":"changes-in-multipolygon-handling-on-the-download-server","status":"publish","type":"post","link":"https:\/\/blog.geofabrik.de\/index.php\/2023\/03\/29\/changes-in-multipolygon-handling-on-the-download-server\/","title":{"rendered":"Changes in multipolygon handling on the download server"},"content":{"rendered":"<p>This weekend we&#8217;ll implement a change that affects the handling of boundary-straddling multipolygons in our OSM extracts. (See <a href=\"http:\/\/blog.geofabrik.de\/?p=397\">this 2017 blog article<\/a> for some background.)<\/p>\n<p>We&#8217;ll stop completing cross-border multipolygons except landuse polygons and a hand-picked list of natural polygons (e.g. water, grassland, wetland).<\/p>\n<p>This has become necessary because of the propensity of OSM mappers to create huge multipolygons like &#8220;the Iberian penisula&#8221; or &#8220;the Alps&#8221;, artifacts that not only unnecessarily increase the data volume of any given PBF but also have unexpected consequences &#8211; for example, for a while anyone processing the rivers of the Switzerland extract would find a stretch of the River Danube in Vienna, because it happened to be part of the outline of the &#8220;Alps&#8221; multipolygon.<\/p>\n<p>We hope that by restricting multipolygon completion to landuse and a small list of natural polygons we&#8217;ll be able to curb these unexpected side effects of polygon completion.<\/p>\n<p>As a result of this change, the .osc.gz files generated on Friday night will contain &#8220;delete&#8221; operations for ways and nodes that were heretofore contained in the extracts due to multipolygon completion, but are not any longer.<\/p>\n<p>Some data extracts, notably those for small islands or archipelagos, will shrink by more than 10%, but for most extracts the size will not be affected dramatically.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This weekend we&#8217;ll implement a change that affects the handling of boundary-straddling multipolygons in our OSM extracts. (See this 2017 blog article for some background.) We&#8217;ll stop completing cross-border multipolygons except landuse polygons and a hand-picked list of natural polygons (e.g. water, grassland, wetland). This has become necessary because of the propensity of OSM mappers [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/posts\/587"}],"collection":[{"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/comments?post=587"}],"version-history":[{"count":0,"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/posts\/587\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/media?parent=587"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/categories?post=587"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.geofabrik.de\/index.php\/wp-json\/wp\/v2\/tags?post=587"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}