![]() This tile is passed back to the client and moves on to the next item in the queue.įor rendering, OpenStreetMap data is stored in a PostgreSQL database created by a tool called osm2pgsql. It pulls requests from the work queue as fast as possible, extracts data from various data sources according to the style information, and renders the tile. We use a tool called Mapnik to render tiles. ![]() If it does need to be rendered, then it will add it to a "render request" queue, and when it gets to the top of the queue, a tile renderer will render it and send the tile back to the client. If it is already available and doesn't need to be rendered, then it immediately sends the tile back to the client. ![]() Mod_tile checks if the tile has already been created and is ready for use or whether it needs to be updated due to not being in the cache already. Once Apache handles the request from the web user, it passes the request to mod_tile to deal with. The Apache web server can also be used to serve static web content like the HTML, JavaScript, or CSS for your map webpage. We use a series of tools for generating and serving map tiles:Īpache provides the front end server that handles requests from your web browser and passes the request to mod_tile. In this example we'll use it simply to show the map that you render, but to learn more about extending it to include these features, please visit. It is very powerful and can be used to add advanced features to your map like buttons, overlays, popup windows and lines. OpenLayers is a JavaScript library for displaying maps on your web site. The OpenLayers library we are using in this example will place these tiles in a grid to form a draggable view of anywhere on the Earth. What are tiles?įor our purposes, a web map is made up of several adjacent square images, each 256 pixels square, that cover a particular geographic region of the Earth. In general, requirements will range from 10-20GB of storage, 4GB of memory, and a modern dual-core processor for a city-sized region to 300GB+ of fast storage, 24GB of memory, and a quad-core processor for the entire planet. Depending on the size of the area you're interested in serving and the traffic you expect the system requirements will vary. Serving your own maps is a fairly intensive task. You might want to do this if you are interested in highlighting a particular kind of OpenStreetMap data like bicycle or foot paths or if you are dissatisfied with the elements present in the other available map styles. In this chapter we'll go farther by describing how to set up your own server with a customized map style based on OpenStreetMap data. This is similar to the earlier section in this book describing the "Export" tab on. The most basic and easiest for you to use is a JavaScript library called OpenLayers that provides a draggable map that you can embed on your own webpage. There are many different options for providing maps on your own web site. For example, a line on the map between Bariloche and Salta, in Argentina, would link to this entry on my site. Nice-to-have would be addition of links, to lines or place markers, to link back to diary entries on my site. I can think of many other things I would like to be able to do but these are the essentials. I also want to indicate direction of travel, such as by showing arrows on lines, either in the middle or at the end of some line segments. I also want to add markers ("round blobs with labels") at specific locations, such as towns, landmarks, places of note. For example, sections travelled by train in one colour, sections travelled by boat in another, etc. If possible, I would like to differentiate (visually) between different legs of a journey. Here's an example of a trip to Andalucia in 2008. At the moment I'm using Google My Maps, but it's not ideal. I want to draw long travel routes, for completed as well as planned trips. One of the answers pointed to a list of "track drawing websites", but they all seem to relate to "sports activity" sites that allow one to upload a GPX track, not edit manually "on the map itself". My question is related to, but not the same as, this one posted a couple of years ago by someone else.
0 Comments
Leave a Reply. |