Base map renderer is Mapnik.
Seamark- and Sport Renderer
- current Seamark layer renderer is purpose-written C program
The Seamark layer renderer work flow is as follows:
1. A local instance of Overpass maintains a minutely updated version of the Planet DB.
2. A shell script makes repeated queries to Overpass to extract all nodes, ways and relations that have a "seamark:type" tag.
3. Another shell script compares the new extract with the previous extract to determine the changes made since the last pass.
4. The script extracts 3x3 zoom12 tile areas from the new OSM file where changes have been made.
5. These 3x3 OSM files are processed by the Searender program to generate SVG image files for each zoom level.
6. The SVG image files are processed by the Apache Batik software to generate the PNG tiles.
7. The PNG tiles are uploaded to the tile server.