The map remains the user's file
THS2 selected PMTiles as its primary offline map container. Before adding a file to the catalogue, the app validates its signature and reads its bounds, centre and zoom levels. MapLibre then reads the local archive directly, without an embedded web server or thousands of extracted tile files.
A modern OSM basemap remains beneath the historical raster. The surrounding area stays readable outside the old map's coverage, while the opacity control helps compare roads, landmarks and boundaries across time.
Layers instead of constant switching
Several PMTiles archives can be enabled at the same time. Each layer has its own visibility and opacity controls, while layer order helps with overlapping sheets.
The active track, current position, findings and Home point are drawn above the offline maps as separate layers. Changing a basemap does not interrupt trip recording or modify field data.