- OpenStreetMap -

The long debate of land-use mapping with OpenStreetMap in Belgium

12.03.2018 - OpenBelgium - LLN

Julien Minet

Champs-Libres.coop

Champs-Libres

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

Why?

Presentation at FOSS4G.be last November

Discussions within the OSM community

Objectives

  • 1. Quantitative assessment of land-use/land-cover mapping in OSM in Belgium
  • 2. Have a look at some applications of OSM land-use data.
  • 3. Discuss some cases/issues
  • GOAL: Some Belgian conventions on land-use mapping with OSM in Belgium

How land-use/land-cover is mapped in OSM?

  • by digitalization on aerial imagery, with user/terrain knowledge
  • by semi-automated import from other database (including Corine Land Cover) (but not so much in Belgium)

Quantitative assessment of land-use/land-cover mapping

[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%!

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]

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 - OCTOBER 2017

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

OSM data from geofabrik, 10/10/2017.

See methodology on github.com/nobohan/OSMLanduseAnalyzer.

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

Results

Total coverage of "land-use" tags by provinces in Belgium - MARCH 2018

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

OSM data from geofabrik, 07/03/2018.

See methodology on github.com/nobohan/OSMLanduseAnalyzer.

Applications

[Applications]

What applications of OSM land-use/land-cover data?

Plain cartography

"Do not map for the renderer" they said...

... but map for the renderers! (paper maps, OpenTopoMap, Thunderforest maps & many many more)

[Applications]

What applications of OSM land-use/land-cover data?

In science

  • support earth observation interpretation / classification: example the lifewatch project.
  • ecological network analysis
  • as base layer for hydrological modelling / flood forecasting
  • as base layer for climate / biogeochimical cycles modelling

[Applications]

What applications of OSM land-use/land-cover data?

Land-use planning, urbanism

[Applications]

Other Volunteered Geographic Information system focused on land-use

  • Geo-wiki challenges: gamification of land-use / vegetation recognition
  • EU research project on land-use data from VGI : LandSense.eu

OSM land-use mapping issues

[OSM land-use mapping issues - geometry]

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 - geometry]

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

See this discussion on the OSM forum.

--> Why not? (it depends)

[OSM land-use mapping issues - geometry]

3. How do we parcellize things, such as gardens, agricultural lands and forests?

[OSM land-use mapping issues - tagging]

4. 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 - tagging]

5. 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 - tagging]

6. 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 - tagging]

7. Which tag for highways areas? landuse=highway vs area:highway=*

[OSM land-use mapping issues - tagging]

8. 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.

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]