Scanning the top of Europe

Reaching the top of Mont Blanc, Europe’s highest peak, is a formidable challenge even to the most experienced alpinists – not only because of its elevation, but also because of its severe weather conditions. Strong winds and snowfall at the summit constantly cause altitude and volume fluctuations to the mountain’s ice cap. This motivated a team of expert surveyors to take on the mountain’s challenge and every two years, determine the actual variations of the ice cap using the latest in measurement technology. This year a team consisting of two surveyors from Leica Geosystems France and the Chartered Land Surveyors, based in France’s Upper Savoy region, decided to make the first ever 3D laser scan of the shape and volume of this legendary glacier using the Leica Nova MS50 MultiStation.

The team of 14 climbers included the surveyors and their technical partners: Covadis (Géomédia), Teria (Exagone) and Leica Geosystems. They were accompanied by guides, a photographer and a cameraman. Leica Geosystems, responsible for measuring the elevation and shape of the ice cap of Mont Blanc, was represented by Farouk Kadded, Product Manager at LGS France, an experienced alpinist and who founded the partnership that was formed with the surveyors from the Upper Savoy region. Farouk has taken part in the expedition since 2001 and explained why 2013 offered an opportunity to add a new technical dimension to the adventure.

Farouk says, “It seemed altogether appropriate to use the world’s first MultiStation, the Leica Nova MS50, to capture the first ever 3D laser scan of the Mont Blanc ice cap. This would save time and provide higher point density than GPS measurements, which we took in previous years. With such extreme temperatures and with wind chill factors of – 10°C (14°F), fast data collection is a real bonus. For the first time, we had at our disposal an instrument that not only combines the latest technologies in the fields of total station measurements, digital imagery, 3D laser scanning and GNSS positioning but is also designed to operate in extreme  conditions. Our only consideration was the additional weight. Transporting the instrument to the summit added about seven kilograms to my backpack but the results were certainly worth it.”

Measurement ambassadors
After taking a deep breath and appreciating the extraordinary view, the team had little time to lose. The temperature felt like – 25°C (– 13°F), with gusting winds of over 50 km/h (31 mph). In order to make a 3D laser scan of the ice cap, they had to quickly prepare and set up the Leica Nova MS50 MultiStation as well as two Leica Viva GS14 receivers: one for taking precise altitude measurements that would later be analysed during post-processing and one receiver on a pole for taking kinematic measurements.

After setting up the first GNSS antenna for two hours of observation, the surveyors got started with the second antenna that would take approximately one hundred measurements of the ice cap. At the same time, Farouk, in charge of the MultiStation, positioned it to scan the ice cap. Minutes later, it recorded almost 100,000 points, despite freezing conditions, which were immediately displayed on the MultiStation’s screen. This confirmed that the survey was complete and the team could begin their descent.

Philippe Borrel, owner of the survey company, Cabinet Borrel and an experienced member of the expedition team, said, “Using the Nova MS50 MultiStation to model the Mont Blanc summit was an exercise in precision measurement, resulting in greater accuracy than traditional topographic surveys. The speed of the data collection and being able to use a minimum number of control points is particularly advantageous when working in such a hostile environment. We significantly cut back the amount of time and energy needed to get the job done and the MultiStation’s size and weight made it surprisingly easy to carry in a backpack, considering the rocky terrain, steep slopes and windy ridges we had to climb.”

What were the exact measurements of Mont Blanc?
The 2013 expedition proved that the current elevation of Mont Blanc is 4,810.02 m (15,780.91 ft), which is 42 cm (16.5 in) less than in 2011. The actual rock summit has an altitude of 4,792 m (15,722 ft), however the snow covering the peak may vary the actual summit’s altitude anywhere from 15 to 20 m (49 to 66 ft). Expedition partner Géomédia calculated the volume of the ice cap covering the rocky summit at 20,213 m³ (26,438 yd³) and produced a 3D animation from the scan data as well. In the future, these results will help researchers determine possible changes to the ice cap caused by global warming.

Farouk Kadded noted, “The MultiStation added a new dimension to the measurement campaign enabling us to produce, for the first time, a precise 3D model of the ice cap of Mont Blanc. Collecting data to millimetre accuracy is a human and technical achievement and this campaign demonstrated that this technology is at the top of its game.”

Written by Marie-Caroline Rondeau