Branching out with mobile mapping

Harriet Brewitt

ZEB-HORIZON

“High quality forestry data captured eight times faster than traditional methods” 

47% of Croatia’s total land area is covered by forest, an area of approximately 25,000km2. Management of these vast valuable assets is a key industry in Croatia and across its central European neighbours. As well as managing the biodiversity and sustainability of the forests, it is important for commercial logging companies to assess the quality and biomass of the forests for responsible timber sales. This assessment is a growing need – every year, Croatia adds 10.5 million m3 of forestry to its stock.

Methods of forestry management typically involve measuring the height, diameter and relative position of trees using equipment such as tape measures, ultrasound instruments, total stations and terrestrial laser scanners. However, there are limitations to these methods – they’re often time consuming, involve multiple setups and numerous members of staff to take the measurements (especially since forestry is usually in remote and difficult to access areas). Due to their dense canopy cover, forests are usually GNSS-denied areas which makes it difficult for instruments like terrestrial laser scanners to work.

GeoSLAM’s Croatian dealer Geocentar have a large client base in the forestry industry and upon delivery of their new ZEB-HORIZON mobile laser scanner, decided to put the technology through its paces and see how it weighs up against other solutions for measuring biomass.


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Data visualised in 3D Forest, showing trunk radius

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Height and position of trees shown in 3D forest software


Visiting the Perivoj Zrinskih park close to Geocentar’s office, the ZEB-HORIZON was initialised on a park bench before the operator navigated around the park at normal walking pace. With a capture range of 100m, It took just 9 minutes in total to walk around the park and capture all the trees.

Back in the office Geocentar processed the data with GeoSLAM Hub software, before filtering with CloudCompare SOR filter then reducing the dataset in size using GeoSLAM Draw. The data was then imported into an open source forestry programme “3D Forest” whereupon several parameters could be measured and extracted automatically including ground extraction, tree detection, tree position detection, tree radius determination, tree height determination, tree crowns detection, crowns volume calculation and crowns collision determination.

Later Geocentar revisited the park to check the accuracy of their results and re-produced the survey using a total station with built-in REM (Remote Elevation Measurement) and a measuring tape. Not only did it take four minutes per tree to capture data due to all the total station setups, only four parameters (diameter, height and relative position) could be calculated using these methods. If they had attempted to measure all 217 trees, it would have taken a whopping 14.5 hours!


The ZEB-HORIZON captures forestry data more accurately than traditional methods
Luka Zalovic, Geocentar D.o.o.

Using the ZEB-HORIZON and 3DForest software, it took 9 minutes to scan the park, 12 to process the data in GeoSLAM Hub, 5 minutes to reduce the data size in Hub and prepare the cloud for the forestry software, which took 90 minutes to process. The total workflow took just under two hours to collect and measure all 217 trees - using traditional methods they could have surveyed just 29 trees in this time.

Geocentar calculated that results were accurate to within 3cm and were more accurate than using traditional methods, leading to great cost savings!

Founded in 1991 and based in Čakovec Croatia, Geocentar are dealers for GeoSLAM across Croatia and neighbouring Slovenia. They offer 30 years’ worth of geospatial experience in the form consulting, training and engineering services across both countries.

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