I have been following with interest the thread on tagging and rendering, and would like to make a slight jump to comment on the inherent limitations for rendering the results.
Whilst I do not wish to stifle the use of a wide-ranging tag-set, and applaud the attempts by folk to get agreement on track surface types, variations in access to highways, types of cycle paths, climbing route grades, types of aerial runways/chairlifts, and deeper and deeper landuse classifications, it should be remembered that there is a limit to the human eye's ability to distinguish between similar colours or linestyles in maps and graphical outputs. There is already a problem on the mapnik slippy map in distinguishing between the green tones employed for various landuse types already in play. Similarly, there is an ever increasing proliferation of linestyles being employed to try to map the variations in types of "way" in different situations. For instance, are you aware of the 7 different styles of purple line used to distinguish admin boundary types on the mapnik layer? So, my point is that if you should reach agreement/concensus on new/deeper tagging, don't automatically think it will be possible to transfer these new "flavours" to the standard renderers (osmarender or mapnik). In the last couple of days I have had requests to render to the mapnik layer natural=cliff and historic=citywalls, and have seen a talk request for rendering nature reserves a second way to incorporate loacations that are aprt of wholly water-based (at the moment it is a green fill with NR overprint). Now there is nothing wrong with any of those requests, but it just adds further complexity to the range of linestyles and fills that have to be in place, and be visually distinguishable, and keyed in the map legend, etc. Some of the examples listed in para 2 are actually better addressed by specific render cases (a bike map, piste map, climbing map for example for some). I imagine these alternate renders will have to become even more abundant. As folk try to map in depth in their particular field of interest they will need to develop in parallel appropriate rendering styles/outputs (as has very successfully happened with cycle interests already). Anyone wanting to read further on graphical symbology and limitations should seek out some of the seminal texts that have been produced by authors such as Bertin, Tufte and Krygier. Cheers STEVE Steve Chilton, Learning Support Fellow Learning and Technical Support Unit Manager School of Health and Social Sciences Middlesex University phone/fax: 020 8411 5355 email: [EMAIL PROTECTED] http://www.mdx.ac.uk/schools/hssc/staff/profiles/technical/chiltons.asp Chair of the Society of Cartographers: http://www.soc.org.uk/ SoC conference 2008: http://www.abdn.ac.uk/cartographers08/ _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
