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Please could someone explain why about 25% of the buildings are not showing on this map of Central London (eg between Hyde Park and the Thames). I have just downloaded the data, as a shapefile, and styled the buildings purple.

I am fairly new to QGIS (and to Stacexchange). The map was produced by:

  1. downloading the data as a Shapefile from mapzen.com
  2. using Layer>Add Vector Layer to add the shapefile to the project
  3. selecting the Buildings layer and changing the style to purple.

I would like to know how to show all the buildings.

[Note: I have tried several ways of making a map with OSM data (Geofabrik, OSM download etc) and am finding that each method has problems I can't resolve. My previous GIS experience was with ArcView, quite a long time ago, and I do not remember problems of this type]. Mapzen Metro Extract West London

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    What were your precise steps to produce that map? What have you considered/tried in terms of explaining the map prior to posting your question? If you hover over the downvote button you will see that research effort is expected to be evident in questions asked here. – PolyGeo Sep 26 '16 at 6:13
  • Sorry about the lack of information. I am fairly new to QGIS (and to Stacexchange). The map was produced by (1) downloading the data as a Shapefile from mapzen.com/data/metro-extracts/metro/london_england (2) using Layer>Add Vector Layer to add the shapefile to the project (3) selecting the Buildings layer and changing the style to purple. [I have tried several ways of making a map with OSM data and am finding that each method has problems I can't resolve. My previous GIS experience was with ArcView, but quite a long time ago] – user83045 Sep 26 '16 at 8:33
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    There is an edit button beneath your question that you can use to revise it with those details. – PolyGeo Sep 26 '16 at 8:34
  • those buildings do not exist on openstreetmaps, which is probably the source of mapzen's data. – Victor Sep 26 '16 at 10:27
  • Yes. It is Openstreetmap data. But the 'missing buildings' appear on the OSM website. I am wondering if the problem is that the polygons for these buildings are not closed in the database. – user83045 Sep 26 '16 at 16:42
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I don't think you're doing anything wrong.. I tried this and got similar results. Hopefully this screenshot will illustrate... I've used QuickMapServices plugin to show an OSM base layer, with the building polygons on top...

enter image description here

Victor is right, the data isn't there, although the cartography sets that expectation.

Bear in mind that a 'grey box' which appears to show buildings in OSM does not necessarily mean that there are buildings polygons there. Look at the area around Sloane Square, on the left half. The grey areas are more likely to be something like a way of type landuse=residential, or an administrative boundary.

Polygons like this are used in rural villages for example, so that you can see the shape of a settlement. Later on, mappers add buildings, which are drawn on top of these grey areas. Here's an example of this.. no building polygons but the clear outlne of a settlement.

You can use the plugin OSM info which lets you point and click on an osm basemap to see what features are there (a bit like the query option on the osm site itself)

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  • confirmed they [buildings] are not mapped see openstreetmap.org/search?query=eaton%20square%20london#map=17/… – Mapperz Sep 26 '16 at 20:59
  • London Shapefile (opendata) editor.giscloud.com/map/299365/london-buildings-free-shp – Mapperz Sep 26 '16 at 21:03
  • Administrative boundaries don't shade the background, these are really landuse polygons. Regarding OSM, keep in mind that you get what you paid for (i.e. nothing). Valuable data still costs money, or is published as open data by the surveying authority. – AndreJ Sep 27 '16 at 5:49
  • Thank you. I think I understand now: the rendered OSM map for the 'missing buildings' is probably generated with the landuse=residential tag. – user83045 Sep 27 '16 at 5:54
  • Thank you for your help. OSM+QGIS takes some getting used to. My previous GIS experience was with ArcVIEW and UK OS data. I'm not sure why but I get more pleasure from QGIS. – user83045 Sep 27 '16 at 15:05

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