El Sábado, 2 de Mayo de 2009, Ernst Radema escribió: > I would like to ask for [...] the BIG picture of the mapping process.
Some people survey with GPSs and convert the data into features. Some people survey with GPSs and use that as a help to trace features. Some people record features with GPS waypoints, paper and pen. Some people record features with GPS tracks and photographs. Others use audio instead of photographs. Some people use aerial photos. Some people just check for consistency errors. Some people print an incomplete map on paper and scribble the missing data on it, then add the missing bits and pieces. Some people import data from other sources (with permission). > * Who decides and how is decided what all these points rare: eg in > Holland ( where I live ) you often encounter a canal, a street, a bike path > and a foot path next to each other. OSM does not have a strict ontology. There is stuff that gets defined by general consensus, and there is stuff that is only used by few people. > * Storage of all this information in a huge database Yep. > * Rendering of database information into visible map-images > * What are OSMarender ( sounds like OpenStreetMaps ) and > * Mapnik rendering ? Osmarender and Mapnik are different ways of making beautiful images with all the data in the database. > * Tiling: maps are cut into tiles of 0,25 x 0,25 degrees on a > Tile-server. Nope. First you need to know what a map projection is. Then, you need to know about the infamous EPSG:900913 projection. Then you need to know about quadtiles. Wikipedia is your friend here. > Is this -more- or less- how mapping Works? Is it completely else? Who has > more information, corrections, additions? The whole picture is huge. OSM is not about maps, it's about map *data*. The "big picture" changes from day to day because there is people researching into new ways to survey, people researching into new ways of editing the data, new ways of storing and retrieving the data, new ways of checking for errors, new ways of rendering maps, new ways of putting the map data to new and unexpected uses..... -- ---------------------------------- Iván Sánchez Ortega <[email protected]> Given the opacity of the product, how could a Windows admin ever know as much about Windows as a UNIX admin does about UNIX?! -- Roger B. A. Klorese on Postfix Mailing List
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