Terrain visibility analysis

Can you see Säntis from Constance?

Short answer: Yes, from the studied outdoor ground-level viewpoint south of Constance’s Bismarck Tower, the reference summit of Säntis is visible in the terrain model over 49.4 km. Model confidence is high, with a summit margin of about +731 m. Eyes are 1.7 m above the DEM. Trees, buildings and haze may obscure the real view. This result does not apply to the tower’s observation platform.

Säntis from Constance: a 49.4 km terrain profile from the outdoor ground-level viewpoint south of Bismarck Tower, with coordinates and local limits.

View the calculation in Sightelo

Key figures

Observation point: Outdoor ground-level viewpoint south of Bismarck Tower, Constance, Germany; Latitude, longitude: 47.6796248, 9.1804727; Modelled ground elevation: 444.4 m; Eye height: 1.7 m
Point of interest: Säntis reference summit, Switzerland
Target elevation: 2,502 m
Straight-line distance: 49.4 km
Direction to the summit: 165.5° (south-southeast)
Modelled summit clearance: +731 m

Terrain profile and line of sight

Detailed profile

Scroll horizontally to explore the full profile on a small screen.

Calculated terrain
Observer–summit sight line
Minimum visibility line
Elevation reference: 0 m

Terrain already includes modelled curvature and refraction (k = 0.13). The grey curve projects a constant elevation of 0 m using that model; it is not an observed sea level. Subtract it from the terrain curve to read elevation. Sight lines remain straight; no second curvature correction is applied. Vertical and horizontal scales differ.

At the summit, the target clears the modelled horizon by 730.5 m. No blocking terrain is calculated. The relief forming the horizon is 44.579 km from A.

The calculation models terrain, Earth curvature and standard atmospheric refraction. It does not model buildings, trees, clouds, haze or local atmospheric variations.

Calculated profile values

Distance (km)	49.4 km
Observer eye altitude	446.1 m
Summit altitude	2502.0 m
Minimum visible target altitude	1771.5 m
Target margin above the modelled horizon	+730.5 m
Minimum local sight-line clearance	+37.5 m
Displayed / calculated samples	495 / 495
Excluded around A / B	200 m / 1500 m
Horizon-forming relief	44.5790 km

Audited calculation: 2026-10-23. The interactive calculator can recalculate with currently available elevation data.

Which point in Constance does this describe?

The observer is the mapped outdoor viewpoint, OSM node 158727225, south of Bismarck Tower on the Raiteberg. This is neither the city centre nor a point on the tower platform. The fixed sight line heads south-southeast towards the 2,502 m Säntis summit reference in Switzerland. It crosses intervening land; the whole route must not be described as a view over lake water. The summit margin of about +731 m measures the summit above the modelled terrain horizon at the target distance. Minimum local clearance along the ray is about 37 m. The two quantities are not interchangeable.

Ground-level visibility is not a tower panorama

The floor height of the Bismarck Tower platform is not sufficiently documented for this study. No tower height is added to the observer. The mapped position has uncertified metre-scale accuracy, and vegetation, structures and steps near the viewpoint are not individually resolved. A currently unobstructed panorama is not guaranteed. A photograph from the top of the tower is not direct evidence for this ground-level point. The first 200 m around the observer are excluded by the standard model. The calculation includes curvature and refraction, k = 0.13; the grey curve projects constant 0 m elevation, not a measured water surface. Swisstopo profile values corroborate a cleared horizon, with different sampling and height reference; the source of values outside Switzerland is not independently established.

Technical details

Observation point coordinates: 47.6796248, 9.1804727
Summit coordinates: 47.249444, 9.343241
Terrain model: Copernicus DEM 90
Eye height: 1.7 m
Refraction used: Standard (k = 0.13)
Sample step: 100 m
Uncertainty threshold: 30 m
Observer exclusion radius: 200 m
Requested summit exclusion radius: 600 m

A positive value means the summit clears the modelled terrain horizon. A negative value means the summit lies below the minimum elevation required to clear that horizon. This value is not the local height of blocking terrain above the sight line.