hotosm
Differentiating building types and abandoned/disued
Currently in the HDM style all buildings look exactly the same regardless of what is in the building=* tag and the tags abandoned:building=* and disused:building=* do not render at all. This issue is a place to brainstorm what kinds of building types we want to differentiate amongst and also how we want to handle abandoned and disused buildings.
My line of thinking is that regarding disused/abandoned we should indicate this by doing some kind of indication that seamlessly integrates with the building type information so that for example a building=hut and an abandoned:building=hut have a consistent look, except for the abandoned marking. One such possibility (and this is just an example) would be to do something like draw a yellow X over disused buildings and a red X over abandoned ones. This way the cartography for the type can be left consistent without having to introduce new color/marking schemes for every possible combination of building type and used/disused/abandoned. This would simplify the stylesheet, but also make the map easier to read.
There are a great many building types listed on the wiki (http://wiki.openstreetmap.org/wiki/Key:building), I would say we should try to differentiate as many types as possible, but we should do so using a 'categorical' approach:
- at low building zoom levels (say 14-16) we don't differentiate at all
- at medium zoom levels (17-18), we differentiate only into 2 or 3 categories like public buildings, residential buildings and minor buildings (garages, sheds, etc), and we do the differentiation by introducing some style element that propagates down to the higher zoom levels as well (like making public buildings darker, residential moderate, and minor buildings light colored
- and then at the highest zooms we add additional markings or style elements to differentiate the individual types in each category: houses from huts from dorms from apartments, sheds from garages, etc. For this differentiation we leave the mid-level prominence distinction in place and then differentiate in this category using some new thing added either with symbology, or maybe even just text since we are at such high zoom now and have space for text (Ga. for Garage, Sh. for shed, etc, is one possibility). Text, symbology, or some kind of texture applied to the various building types will avoid us having to make dozens of color and line style combinations that are impossible for map readers to remember.
Styling buildings has been briefly mentioned before - https://github.com/hotosm/HDM-JOSM-style/issues/17 I'd like to get a stronger consensus or idea of what should be done (if anything - or just leave it to the expectation that if someone wants to use in this a disaster scenario, they'd just need to rewrite the building layer and its SQL query for their needs) or have some action being taken on this.
I'm in favour of having more rendering distinctions for buildings than we have now, but imho we don't need to go on "try to differentiate as many types as possible"; again, too much informations kill information, and our rendering is not targeted for craiglist or whatever house sellers ;)
So in my opinion we should extract some important categories, like public, offices, private, inhabited (garage...), plus maybe crossing as suggested by @AndrewBuck with abandoned/disused at low zoom level.
