A log stack measurement tool sets new standards

In 2005, storms Erwin and Gudrun caused 85 million m³ of damaged wood in Scandinavia and the Baltic states. The following year, Dr. Kim Dralle, forester and IT expert, used his newly developed tool sScale, a complete system for measuring log stacks, on a large scale in Sweden. In Germany, the Bavarian State Forests (BaySF) became aware of the Danish entrepreneur and wanted to use the stack measurement system with its stereo camera and image processing software in the Free State. In trial operation since 2008, the BaySF have been using four sScale measurement units in their forests since 2011. Around 9,000 m³ a day, i.e. a total of 1 million m³ a year in 25,000 individual stacks, are measured with this system. ThüringenForst works with eight sScale units and measures all softwood log stacks in its forests. In addition to core market Germany, an sScale solution will also be in use in Ireland starting in 2024.

Fast and accurate log measurement at any time

Using cameras which are mounted on a car, sScale measures the stacks with a deviation of less than 3% as the car drives past. The roof construction, called “Drallemobile”, also works on uneven roads, at night and in bad weather. The driver does not have to get out of the car while the stack is measured. The built-in touchscreen inside the vehicle can be operated very easily and intuitively. According to Ulrich Heindl, Dralle’s regional manager in Germany, the ability of Dralle’s solution to measure both very long and very high stacks quickly and with high precision is a definite advantage over photo-optical measurement systems on mobile devices. “I have to drive to the stack anyway, so why get out of the car to take one or several photos if I don’t have to? Thanks to the wide baseline between the cameras, sScale achieves extremely high data quality. Also, the whole system is very robust. It doesn’t break during normal operation.”

From Heindl’s experience, one person can measure around 250,000 to 300,000 m³ of log wood a year with one measurement unit. In the event of calamity, up to 450,000 m³ a year are possible. “The measurement in the forest by the forest owner will not disappear as a control measure in the foreseeable future. Dralle’s solution simplifies and accelerates the flow of wood and information, while minimizing logistics costs and facilitating documentation. It also makes wood sales more transparent,” Heindl is convinced. The system costs are 20 to 30 cents per cubic meter. According to Heindl, using sScale pays off for a minimum measurement volume of 80,000 m³ a year.

A fast billing system

With its measurement tool, Dralle also acts as a service provider. “This option is particularly interesting for smaller volumes or operations of limited duration, for example after calamities when damaged wood needs to be processed,” Heindl explains. So far, private forest owners are a minority customer group compared state forests and the like. Heindl sees the often poor realignment of the boundaries of land owned by forestry companies, the lower logging rate, smaller stacks (maximum 20 m³) but also a general reserve when it comes to external providers of measurement software as reasons for this. “The question of who has control over the measuring process and concerns of forest owners about losing control over their sales volumes also play a role here,” Heindl analyzes. The benefits of digital measurement are often not recognized. “Not everyone sees the advantage of spending more money on log measurement. Some private forest owners, but also forestry businesses or forest owners’ associations, simply don’t know how much conventional measurement with all the downstream processes costs and how much money and time they could save with Dralle’s measurement solutions,” Heindl explains.

In 2016, sScale received the type examination certificate, making it the first photo-optical measurement system to be certified by the National German Metrology Institute. As a result, it is fully usable for business transactions. So far, Dralle’s system has been used primarily in the softwood sector, but it has also reached an accuracy of over 95% in measuring industrial hardwood since the 2021 update.

The “upgraded calculator”

The Android app mScale supports traditional manual methods of measuring log volumes in the forest, since all recorded measurement data in the section measuring process or in individual log measuring are immediately recorded digitally. The counting function enables a quicker and more precise determination of the number of logs in the stack. “With the speech recognition function, measured values can easily be dictated. The diameters of a sample are recorded manually and extrapolated to the whole stack. mScale works on any Android-based mobile device and complements sScale. It is a good choice for small stacks where the use of sScale wouldn’t pay off,” Heindl emphasizes. As is the case with its “big brother” sScale, all data recorded with mScale are transmitted to the card-based Dralle web server, an integrated part of the “stacks” logistics concept.

Measuring bulk materials

The stationary load measurement system tScale works according to the same principles as sScale. When trucks or rail wagons pass through, the photo-optical system takes photos of the bulk cargo or the load of logs from above and from the sides. The result is the volume of the load. The number of pieces and diameters are not recorded.

In collaboration with Mercer Germany, three tScale, two truck and one rail wagon portal measurement systems were installed at the pulp mills in Stendal and Blankenstein where they have been in trial operation since the beginning of 2022. The goal is to measure and digitalize wood chips and industrial log wood in a completely automated way and in compliance with the law. Heindl is very confident that the company will receive the metrological approval for trucks in the area of wood chips during the first quarter of 2024. The certification process in the area of rail loading should be completed by the end of the third quarter.

Aksel Baunsgaard-Pedersen, Sales and Marketing Europe at Dralle, sees great potential in the cargo space measurement of bulk goods, which are traditionally billed in tonnes, and gives mining and shipping as examples. According to Baunsgaard-Pedersen, the measurement of sawmill by-products, such as bark, sawdust and wood chips, which sawmills usually sell and do not use themselves, represents another area of application for tScale.

Even if sScale is used primarily in the forestry industry and tScale is more commonly used in the timber industry, Dralle’s solutions are not aimed at specific customer groups. Heindl sees possible uses for tScale in the forest, to be precise in the management of wet and dry storage places for damaged wood after calamities. If the supply of raw materials becomes more limited over the medium term, the timber and sawmill industries could use sScale to secure access to the log wood and to make an offer to the forest owner on site and before delivery. For example, sScale was used at Schwaiger Holzindustrie in Hengersberg/DE in 2017. After a regional calamity event, the sawmill wanted to measure its log stacks quickly, precisely and cost-effectively.