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Crisis Response Journal Crisis Response Journal

High-tech drone mapping in the ‘forest of violins’

Posted on 16th July 2020 at 14:17pm

Pix4D reflects on how it helped local authorities gain situational awareness in minutes following a windstorm that devastated part of Northern Italy back in October 2018.

An estimated 8.5 million trees were felled during the storm. Recovery work had to take place before the snow set in (Photo courtesy of Pix4D and Servizio Antincendi e Protezione Civile, italy)

Large parts of the Provincial Forest of Paneveggio in the north-east of the country were destroyed as winds of up to 217kph uprooted an estimated 8.5 million trees.

After a request from Agenzia provinciale per le Foreste demaniali – the agency for province-owned forest – first on the scene was Servizio Antincendi e Protezione Civile (SAPC), a specialised group from the local firefighting department. The SAPC team has a small fleet of UAVs and works with the local government to provide inspections, photogrammetric surveys and search and rescue.

After the windstorm, the team used rapid mapping with drones to provide a quantitative survey which allowed forestry management teams to evaluate the damage and assess the best course of action before winter's snows halted work.

A forest of violins

The Paneveggio forest is special. The unique meteorological conditions of this Unesco World Heritage site produce a wood with resonance. Light and elastic resonance wood is used to create fine instruments, such as Stradivarius violins.

The forest is carefully tended according to traditional practices. Spruce trees are harvested under a waning Autumn moon, and the best quality wood is still processed by hand. Before the windstorm devastated the region, some 6,000m3 of wood were felled each year, with only 20 to 50m3 being suitable for resonance wood. A cubic metre of resonance wood can sell for as much as €15,000: 136 times more than the same volume of ‘normal’ spruce.

To salvage some of the precious wood, and begin the long clean-up effort, the team needed to provide surveys to the forestry management – and fast.

As a SAPC team member explained: “Near the forestry management agencies headquarters, for example, there is more than one square kilometre, which is completely without trees. Every single tree has fallen down.”

Situational awareness in minutes

While the affected area was very large, the team concentrated on just 11 badly-affected areas and some parts of a nearby provincial forest in the Cadino Valley. The surveyed areas covered less than ten square kilometres, yet were representative of the damage in the wider forests.

“The forestry management service understood how many trees were in each area. By collecting images of damaged trees in a small area, they could extrapolate this data across the forest and estimate the total damage,” said a team member.

To stay within Italy’s laws surrounding drone flight, the team found the highest possible point for takeoff, and either plotted a flight path in the free Pix4Dcapture app, or flew manually – a skill perfected with search and rescue missions.

To ensure the forestry service could act on the images as quickly as possible, they were uploaded directly to Pix4Dcloud, which automatically creates a 3D model.

By uploading images directly to Pix4Dcloud, the team were able to deliver results within two hours of take-off. “Pix4D processes very quickly, particularly with the rapid option selected,” explained of the team. “You can have situational awareness only a few minutes after the flight.”

The forestry management personnel were able to view the results directly in their browser, saying that: “In particular the 3D area calculation is a very important feature for mountain areas.”

Counting the cost

Within weeks of the windstorm, the forest management service had all the information they needed to estimate the damage and begin the years-long project of forest recovery. Throughout Northern Italy, the windstorm caused more than two-billion euros’ worth of damage.

The UAV team's red car in the bottom left of this image gives some idea of the scale of the damage (Photo courtesy of Pix4D and Servizio Antincendi e Protezione Civile, Italy)

The forestry staff who manage the Paneveggio Forest estimated that around 70 per cent of the timber felled by the wind could be recovered.

Of the recovered timber, around 40 per cent would be good quality wood for carpentry use, and another 40 per cent could be used by the packaging industry. A further 15 per cent could be used as biomass for heating. Sadly, only around one or two per cent of the recovered wood would be suitable for constructing musical instruments.

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