FOSS4G Hiroshima 2026 - Seamlessly Compare Maps on QGIS with the QMapCompare Plugin

Comparing differences between basemaps or datasets in QGIS is difficult when only one map can be viewed at a time. QMapCompare solves this by bringing interactive map comparison into QGIS.
The plugin supports multiple visualization methods to quickly reveal changes across styles and datasets.

Transcript

1. Raymond Lay QMapCompare Seamlessly Compare Maps on QGIS 1 September 2026
2. Introduction About Me Raymond Lay GIS Engineer • 2011- IGN (Saint-Mandé, France) • 2017- Nightley Inc. (Tokyo, Japan) • 2022- MIERUNE Inc. (Sapporo, Japan) Raymond Lay bordoray
3. About Us Headquarters Reading: /mjɛlɯ̹ne/ me-eh-loo-neh Meaning: You can see it! Branch office FOSS4G 2026 venue
4. 10:00–11:30 14:00–14:30 14:20–14:25 ▷ 16:30–17:00 17:30–18:00
5. 13:20–13:25 14:00–14:30 14:00–14:30 15:30–16:00 15:30–16:00 16:00–16:30 16:30–17:00 17:00–17:30
6. 11:30–12:00 14:00–14:30 14:30–15:00 14:30–15:00
7. About Us QGIS MapLibre Mapterhorn FOSS4G Hiroshima
8. About Us 01 qgis-biz.mierune.co.jp 02 03
9. About Us https://plugins.qgis.org/plugins/author/MIERUNE%20Inc./ 0Inc./
10. Save the date kumoy.io/en n Talk on Sep 3, 11:30
11. Why QMapCompare?
12. ©️IGN - 2026 remonterletemps.ign.fr
13. ©️IGN - 2026 remonterletemps.ign.fr
14. ©️IGN - 2026 remonterletemps.ign.fr
15. ©️IGN - 2026 remonterletemps.ign.fr
16. ©️IGN - 2026 remonterletemps.ign.fr
17. ©️IGN - 2026 remonterletemps.ign.fr
18. https://www.qgistutorials.com/en/docs/3/interactive_reveal_maps.htm
19. https://www.qgistutorials.com/en/docs/3/interactive_reveal_maps.htm
20. Why not automate it? https://www.qgistutorials.com/en/docs/3/interactive_reveal_maps.htm
22. QMapCompare Features
23. Places a duplicate of the map canvas on the right side of the map canvas. ©️ Geospatial Information Authority of Japan
24. Divides the map into two sections, showing different layers side by side. ©️ Geospatial Information Authority of Japan
25. You can choose either a vertical or horizontal split. ©️ Geospatial Information Authority of Japan
26. Lens mode displays a circular preview of the comparison layers around the mouse cursor. ©️ Geospatial Information Authority of Japan
27. You can customize the lens shape and size. ©️ Geospatial Information Authority of Japan
28. Use Cases
29. ©️ Geospatial Information Authority of Japan
30. ©️ Geospatial Information Authority of Japan
31. ©️ Geospatial Information Authority of Japan ©️ OpenStreetMap contributors
32. Demo
33. Demo https://drive.google.com/file/d/14uSgREQl57TYGlSpk47Wg2etDqjhkyUD/view?usp=sharing ©️ Ge os pat i al Infor mat i onA ut hor i t yof J apan
34. Limitations
35. Issues regarding Lens view Lens mode may not work in the case of data where rendering takes a while. Possible causes: - High volume of data - Bad network - Layers that need CRS transformation
36. Issues regarding Lens view Lens mode may not work in the case of data where rendering takes a while. Possible solutions: - Make the project CRS and the comparison layer CRS the same - Set a longer refresh interval for the mask layer - Make the data lighter
37. Thank you! Any issue? Feel Free to Contribute! github.com/MIERUNE/qgis-plugin-qmapcompare