- OpenStreetMap -

State of the land-use mapping in Belgium

26.10.2017 - FOSS4G.be - Bxl

Julien Minet

Champs-Libres.coop

Champs-Libres

This presentation and scripts are available on github.com/nobohan/OSMLanduseAnalyzer.

Why?

link link

Objectives

  • 1. Quantitative assessment of land-use/land-cover mapping in OSM in Belgium
  • 2. Discuss some cases/issues
  • GOAL: Some Belgian conventions on land-use mapping with OSM in Belgium

Quantitative assessment of land-use/land-cover mapping

[Quantitative assessment of land-use/land-cover mapping]

Methodology

OSM data was downloaded from geofabrik on the 10/10/2017.

See methodology on github.com/nobohan/OSMLanduseAnalyzer.

[Quantitative assessment of land-use/land-cover mapping]

Methodology

Selection of tags (key=value) for "land-use"

Tag list inspired by the "land-use" preset of OSM-Bright


waterway=riverbank;
landuse=basin,reservoir,park,forest,residential,retail,commercial,industrial,railway,cemetery,grass,farmyard,farm,farmland,wood,meadow,village_green,recreation_ground,allotments,quarry,orchard,vineyard,greenhouse_horticulture;
leisure=park,garden,playground,golf_course,sports_centre,pitch,stadium,common,nature_reserve;
natural=wood,land,scrub,wetland,water,heath,grassland;
highway=pedestrian,footway;
amenity=university,school,college,library,fuel,parking,cinema,theatre,place_of_worship,hospital;
place=island;
aeroway=aerodrome,helipad,apron
      

[Quantitative assessment of land-use/land-cover mapping]

Results

Global share of "land-use" tags in Belgium

Note that many "land-use" polygons overlap to each other. Sum of classes > 100%!

[Quantitative assessment of land-use/land-cover mapping]

Results

Share of some (not all) land-use class in Belgium in CorineLandCover

[Quantitative assessment of land-use/land-cover mapping]

Results

Share of agricultural "land-use" tags in Belgium

[Quantitative assessment of land-use/land-cover mapping]

Results

Part of forested "land-use" that is defined by leaf_type in Belgium

The deprecated `wood=*` tags are not considered here.

[Quantitative assessment of land-use/land-cover mapping]

Results

Part of forested "land-use" that is defined by leaf_cycle in Belgium

The deprecated `wood=*` tags are not considered here.

[Quantitative assessment of land-use/land-cover mapping]

Results

Total coverage of "land-use" tags by provinces in Belgium

Overlapping "land-use" polygons were dissolved before computing this coverage!

OSM land-use mapping issues

[OSM land-use mapping issues]

1. Should land-use nodes be shared with nodes of adjacent (linear) features?

See this discussion on the OSM forum

--> We should not

PROS CONS

Geographic features are digitalized with keeping their real ground footprint

This allows more features to be mapped in the future (hedges, ditches, ...)

The "OSM land-use" database is not continuous

Nodes are somehow duplicated: increase in database size

[OSM land-use mapping issues]

2. Should we superimpose "land-use" features?

See this discussion on the OSM forum.

--> Why not? (it depends)

[OSM land-use mapping issues]

3. natural=wood vs landuse=forest for mapping forests in Belgium

See this discussion on the OSM forum and the Forest wiki page

--> I prefer landuse=forest

[OSM land-use mapping issues]

4. landuse=farmland vs landuse=meadow for mapping meadows in Belgium

Arable land: landuse=farmland + crop=*

Grazed meadows: landuse=meadow + meadow=agricultural + animal=yes

Hay meadows: landuse=meadow + meadow=agricultural + crop=grass

These tags are often (unappropriately) mixed up!

[OSM land-use mapping issues]

5. Better describe leaf_type | leaf_cycle in forests?

Note that forests are rendered by "leaf_type" since the last carto-osm update in August 2017

[OSM land-use mapping issues]

6. Confusion between land-use & land-cover in OSM

e.g., landuse=grass is a land-cover tag.

landcover=* tags are not rendered

natural=* tags are often pure land-use (and not natural features, at least in Belgium). For instance, most of Belgian ponds are artificial and are tagged as natural=water+water=pond.

Perspectives: OSM as a land-use/land-cover database?

  • Use OSM as an auxilliary data for updating land-use/land-cover maps. See the research project landsense.eu. See also osmlanduse.org Collaboration between crowdsourced geodata collection and professional land-use mapping project/agencies would be welcome.
  • At the long term, frequently updated information could be used for historical reconstruction of land-use --> In the future, would it be possible to use OSM to study land-use/land-cover changes?
  • My opinion: No use to import CorineLandCover features in OSM in Belgium.
  • My opinion: OSM as it is not a land-use/land-cover map and should not become one.

References

Some scientific articles on the issue:

  • Production of a land-cover map from OSM and automatic gap-filling with remote sensing data: Schultz et al., Open land cover from OpenStreetMap and remote sensing, International Journal of Applied Earth Observation and Geoinformation, 2017. [link] + the blog article
  • Assessment of land-use classification and accuracy in OSM in Vienna, Austria : Arsanjani et al., Toward mapping land-use patterns from volunteered geographic information, International Journal of Geographical Information Science, 2013 [link]
  • Comparison of OSM against Corine Land Cover in Portugal : Estima & Painho, Exploratory analysis of OpenStreetMap for land use classification, 2013 [link]
  • Accuracy of natural features in OSM (several countries): Winstanley, A study of data representation of natural features in OpenStreetMap, Proceedings of GIScience, 2010 [link]