The Haute Traversée de Belledonne runs 131 km from Aiguebelle to Vizille. Each frame is a viewshed from eye height (1.7 m) on the trail, about every 150 m: amber is the ground in sight at that step, the faint tint is everything already seen. 900 runs of gdal_viewshed on IGN RGE ALTI at 50 m, with Earth curvature and refraction and no distance cap.
| Place | Altitude | Ground in sight |
|---|---|---|
| Grand Chat (widest view on the route) | 1,992 m | 552 km² |
| Refuge des 7 Laux | 2,135 m | 13 km² |
| Col de la Vache (highest point) | 2,556 m | 145 km² |
| Refuge de La Pra | 2,105 m | 2 km² |
| Chamrousse ski area, best spot | 1,669 m | 311 km² |
| Whole route, seen at least once | 2,225 km² |
Bare earth: forests and buildings do not block the view. Terrain loaded to at least 35 km around the trail; views reach up to 93 km. Trail © OpenStreetMap contributors (ODbL). Terrain IGN RGE ALTI via the Géoplateforme (Licence Ouverte 2.0). Method, numbers and scripts: README and code on GitHub.