OpenHistoricalMap Quality and Coverage Stats

This page tracks quality and coverage metrics for OpenHistoricalMap using the daily planet files. Each chart shows metrics for the most recent day. Mouse over the chart to see earlier days. Click a number on the right for an explanation of it and examples. Click and drag to zoom any chart, either horizontally or vertically. Double-click to reset the zoom.

Coverage

Earth Years by admin_level

This tracks the area covered by admin_level=N features through time. The units are "earth years:" all of earth's land area (149 million sq km) for one year would be one earth year. Alternatively, Africa is about 20% of the earth's land area. So mapping all of Africa for one century would count as 0.2*100=20 earth years.

If two features cover the same area in the same year, then there will be double-counting. If you'd like to help fix this, take a look at earth_coverage.py.

Raw features

Total nodes, ways and relations in OHM. Note the log scale.

Data Quality / Correctness

Geometry Errors

This tracks various types of geometry problems for relations with [boundary]. These often correspond to errors that are flagged by the JOSM Validator. Members ways in the relations are grouped into inner and outer rings using something like OSM's Multipolygon Algorithm. These are then processed using shapely, which reports other pathologies through its explain_validity method. See bad_geometry.py for details.

Chronology Errors

This tracks problems with type=chronology relations. See chrono_stats.py for details.

Duplicate Features

🚧 Work in Progress

Tag Errors

Various problems with OHM tags like start_date and end_date.