CoE-LaSR seminar: Laser scanning in forestry – from science to operational applications

Collaboration between researchers from the Department of Forest Sciences (University of Helsinki) and end users from industry, consulting, and governmental organizations, for example, has been one of the main aims when developing forest applications within the Centre of Excellence in Laser Scanning (CoE-LaSR). Department of Forest Sciences organized a seminar for stakeholders to present the latest research and results using laser scanning for precision forestry. The seminar also reached students and other faculty members from the Department of Forest Sciences apart from the researchers of the CoE-LaSR.

Measuring intensity of seedlings of Norway spruce with terrestrial laser scanning. © Centre of Excellence, Samuli Junttila.

 

During the afternoon seminar, recent research related to especially TLS and its application in forest mapping and monitoring were presented. The topics included, among others, identifying dead wood, measuring and modelling tree structure and growth as well as health status and wood quality. Furthermore, presentations included experiences from tree species detection and use of augmented reality for harvester drivers.

Detected dead wood from terrestrial laser scanning data. © Centre of Excellence, Tuomas Yrttimaa.

 

Intriguing discussion between participants and presenters emerged especially towards the end of the seminar which continued with a panel discussion. The panelists represented Natural Resources Institute, the City of Helsinki, Metsähallitus, Tapio, Metsäteho, Stora Enso and Finnish Forestry Center, all utilizing either laser scanning or products based on laser scanning such as forest resource information. The panelists described how they see laser scanning in the field of forestry and forest sciences, and also pointed out where research efforts are still needed. These included improving accuracy of estimates for species-specific forest inventory attributes and tree-size distributions as well as logging recovery. In addition, measuring quality attributes such as branchiness from standing trees was seen as important research topic by forest industry.

Panelists discussing laser scanning and its opportunities in forestry and forest sciences. © Centre of Excellence.

CoE -LaSR -research popular in international media in 2016

Laser scanning research got recognition among the international media in 2016. Our “sleeping trees” findings and advances in mobile laser scanning gained international audiences both in scientific journals and popular news. Two articles by CoE -LaSR researchers were in the top 10 of GIM International magazine’s most read articles 2016, and a Coe – LaSR cooperation  article on birch tree’s day-night cycles was listed as one of the 12 best science stories of the year by The New Scientist.

The articles in GIM International brought insight into topics of personal laser scanners (PLS) and unmanned aerial systems (UAS). The main interest and focus was on the development of new scanning systems and potential applications utilizing them in 3D data collection.

 

First high performance backpack system Akhka in spotlight

 

GIM readers appreciated Kukko’s, Kaartinen’s and Virtanen’s insights into the advantages of personal laser scanners (PLS) such as Akhka R2 PLS in mapping complex environments presented in the article Laser Scanner in a Backpack – The Evolution towards All-terrain Personal Laser Scanners in GIM International 15/02/2016.

Backpack system allows data acquisition in environments, which have before been hard, or even impossible, to reach with “conventional” wheeled mobile laser scanning systems (MLS).

 

To our knowledge, the Akhka PLS system has been the first backpack system with such high data acquisition capability. After the publication of this article, an updated revision, AkhkaR3, has been released with even higher performance sensors.

The current possibilities and future opportunities for using new and more cost-effective laser scanning methods were discussed in the article The Current State of the Art in UAS-based Laser Scanning – Airborne Laser Scanning with a UAS  by Kukko, Jaakkola and Hyyppä. The article gives an overview of different types of UASs, both current and emerging laser scanners and UAS laser scanning applications.

 

New research fields for laser scanning for plant dynamics

 

The New Scientist story ‘Trees seen resting branches while ‘asleep’ for the first time illustrated a novel application of using the high potential of terrestrial laser scanning measurements in the field of chronobiology. The study, a joint international research collaboration with Dr. Eetu Puttonen from NLS FGI and TU Wien, clearly demonstrated circadian movements of silver birch branches and showed for the first time that lidar measurements can detect nocturnal physical changes in trees that resemble a resting or a sleeping pattern.

Above: Overnight movement of a small tree acquired with three different terrestrial laser scanners. Each frame represents the point clouds measured at the shown time with color. The point coloring shows the reflectance of each measured point that were calibrated using an external calibration target. The black point cloud shows the tree’s original posture at sunset.

 

The results were exciting as they support the use of high resolution terrestrial laser scanning in monitoring plant dynamics with short time intervals and in a non-destructive manner. Additionally, the laser scanning measurements can be scaled up to cover for example several full-grown trees of different species simultaneously with short preparation times.

Read the original research article: Frontiers in Plant Science: Quantification of Overnight Movement of Birch (Betula pendula) Branches and Foliage with Short Interval Terrestrial Laser Scanning

 

Hyperspectral dataset available as open data

Our novel Hyperspectral Terrestrial Laser Scanning (TLS) dataset has been published as open data.

The laser scanning point cloud dataset consists of 30 individual scans collected as a time series covering a 26 hour time frame. Each point in the laser scanning point cloud contains colour information from several different wavelengths. Ordinary laser scanning data has colour information from one wavelength.

Presentation of hyperspectral data

Hyperspectral data on a birch

 

Compared to traditional laser scanning data, hyperspectral data has advantages in for example target recognition and change detection, where it is possible to track changes of color of tree leaves, as in the data published. Also 3D RGB presentations can be produced from data without using separate camera. All laser scanners enable collecting data without external light source, also in the dark.

The dataset is available via the Etsin research data finding service provided by the Finnish Ministry of Education and Culture (http://urn.fi/urn:nbn:fi:csc-ida-4x201604052015015324658s). Datasets are provided in .laz format and published under the Creative Commons Attribution 4.0 International License (CC-BY-40).

The data has been utilised in recent research on movement of a birch during a 26 hour period, where it was found out that trees “sleep” during night. Click the picture below to see an animation on the movement of a tree:

Movement of a birch during 26 hour period

Movement of a birch during the night.

 

More information: Dr. Eetu Puttonen, eetu.puttonen(a)nls.fi

Read more on the published data at the National Land Survey and about the sleeping trees at the NLS and TU Wien press releases

 

 

 

Capturing Urban Data with Backpack Laser Scanning

Personal mobile mapping on a backpack (PLS) is a novel innovation from FGI. The application uses various technologies: GNSS-IMU positioning, laser scanning, digital photography and data driven algorithms for improving the positioning in often GNSS denied urban space. PLS allows rapid data collection of complex environment without compromising the data coverage, precision and accuracy of data. The approach is a flexible solution for varied situations and mapping tasks in urban space, and applicable to e.g. building façade reconstruction, street mapping, urban arboculture and change detection.
The research aims at development of modern surveying practices, investigates alternative system and sensor layouts and performance related issues as well as formulates automated data processes for 3D modeling and seeks for methods for improving geometric quality of data and data fusion.

More information: Dr. Antero Kukko, Antero.Kukko(a)nls.fi

 

Capturing urban data with PLS

Above: 3D geometry and imagery are collected simultaneously using backpack PLS providing an efficient tool for urban mapping.

 

Point cloud model of a building

Above: Point cloud data collected with backpack PLS captures building geometry fast in high details and accuracy.

 

Mobile laser scanning with Akhka

Laser Scanner in a Backpack – The Evolution towards All-terrain Personal Laser Scanners

Personal laser scanners (PLS) lead the way towards compact, agile and flexible solutions for mapping complex environments and challenging locations, such as rugged terrain and complicated urban structures. Our Akhka R2 backpack laser scanning system allows the operator to move in and around the scene while capturing the environment with millimetre precision. Read more about the latest development in the GIM International article Laser Scanner in a Backpack – The Evolution towards All-terrain Personal Laser Scanners. 

More information:

Dr. Antero Kukko, Antero.Kukko(a)nls.fi

Next generation forest management: High detail information from laser scanning

Picture above: Preparing to collect terrestrial laser scanning data from old Norway spruce forest.

High detail remote sensing technologies, especially laser scanning, and their ability to measure 3D structure of the forest have revolutionized forest mapping and monitoring applications.

“For example in Finland, forest management practices have been based on intensive small-scale forestry because the forests are mainly privately-owned and the size of an average forest holding is relatively small. This creates demanding surroundings for the used remote sensing systems.” New CoE-doctor Ville Kankare says.

The main objective of Kankare’s Ph.D. thesis at the Department of forest sciences, University of Helsinki, was to develop high density laser scanning methodologies for individual tree-level forest mapping. The thesis was accepted in June 2015.

The results of this thesis indicate that high density laser scanning is a vital option for measuring the required individual tree-level attributes, such as tree biomass, timber assortments, quality and stem curve. This type of information will play an important role in the next generation’s forest resource mapping systems especially where the added value for the information is the highest.

The main goal in forest resource mapping is to produce accurate information about forest structure and resources for forest owners, managers and forest industry. The precise knowledge of the biomass (bioenergy potential), logging recoveries and the quality of the available timber plays an essential role for example

  • when forest owner request tenders for the planned forest management procedures or
  • when forest industry is optimizing the flow of raw material from forest to the final product.

“The economic value and profitability of forest holding rely on detailed and up-to-date information of forest structure and attributes.“ Kankare concludes.

high-detail terrestrial laser scanning data presentation of forest

Picture: Representation of the Scots pine forest measured with terrestrial laser scanning.

 

More information: Ph.D. Ville Kankare, ville.kankare( at )helsinki.fi

Ph.D. thesis: “The prediction of single-tree biomass, logging recoveries and quality attributes with laser scanning techniques” available at https://helda.helsinki.fi/handle/10138/154644

Study: Leafy areas are the coolest in cities

Land type has an impact on local weather in urban areas, according to the findings of a joint study of CoE, University of Helsinki and Finnish Meteorological Institute (FMI).  The local temperature can vary several degrees and even small pockets of trees, water and parkland can bring a relief on hot days in the concrete jungle. Read more in the recent story in the Guardian. The research results have been published as a scientific article Urban surface cover determined with airborne lidar at 2 m resolution – Implications for surface energy balance modelling in the journal Urban Climate.

 

Current events: Three doctoral defenses

Three new doctors are expected in the Centre of Excellence as Ville Kankare (Univ. of Helsinki), Anttoni Jaakkola and Lingli Zhu (FGI) are defending their doctoral dissertations in June:

Anttoni Jaakkola‘s defense on his doctoral dissertation Low-cost mobile laser scanning and its feasibility for environmental mapping (Edullinen liikkuva laserkeilaus ja sen soveltuvuus ympäristönkartoitussovelluksiin) will be held in Aalto University, TUAS-building, Hall AS1, Otaniementie 17Espoo, on 5 June 2015 at 12:oo. Read more on the news section

Ville Kankare will defend the doctoral dissertation entitled The prediction of single-tree biomass, logging recoveries and quality attributes with laser scanning techniques (Laserkeilaus puutason biomassan, puutavaralajien sekä laatutiedon ennustamisessa) in the Faculty of Agriculture and Forestry, University of Helsinki,also on 5 June 2015 at 12:00. The public examination will take place at the following address: EE-talo, Walter-sali, Agnes Sjöbergin katu 2. Read more

The public examination of the doctoral dissertation of Lingli Zhu will be held on 18 June 2015 at 12.00 at the Aalto University School of Engineering, Lecture hall M1, Otakaari 1, Espoo. The title of the dissertation is A Pipeline for 3D Scene Reconstruction from Point Clouds (Rakennetun ympäristön kolmiulotteinen mallintaminen pistepilvistä). Read more

 

 

A versatile low-cost mobile laser scanner system: New opportunities for applications

A novel low-cost multi-sensor mobile laser scanning system has been developed at FGI CoE-LaSR by Anttoni Jaakkola. This work is the focus of his Dr. Sc. thesis, presented in the public examination on 5th June 2015 (Press release in Finnish).

“The results show that mobile laser scanning is a feasible method for various applications of mapping the environment and that even a low-cost system can perform sufficiently in these measurements” Anttoni Jaakkola concludes.

The developed system has been demonstrated on car and UAV (umanned aerial vehicle) platforms. It allows recognizing and classifying different features in the scanned environment, i.e. those of trees, roads and snow depth more accurately compared to the formerly used systems.

With future advances of laser scanning and positioning technologies, it can be expected that price of these systems will further decrease. Widespread adoption of laser scanners, especially in the automotive industry and the new global navigation satellite systems, will significantly reduce the cost of mobile laser scanning components. Nowadays expensive mobile laser scanning systems are almost exclusively owned by mapping companies as benefits of using them requires high rates of utilization and applications with high added-value.

“With future cost reduction, mobile laser scanning will expand to new fields, as also other companies can afford to acquire such systems and utilize them in various applications.” Jaakkola foresees.

Mobile laser scanning is a measurement technology that combines accurate positioning and attitude information from navigation satellites and inertial sensors with distance measurements from a laser scanner into a point cloud that represents the geometry of the environment surrounding the measurement platform. This geometrical information can be utilized in a variety of applications ranging from 3D city modelling and infrastructure maintenance to forestry and environmental monitoring.

Picture: Anttoni Jaakkola (left) demonstrating the UAV mobile laser scanning system

More information: Senior Research Scientist Anttoni Jaakkola, anttoni.jaakkola(at)nls.fi, tel 358 50 3498 108

Dr.Sc. thesis Low-cost Mobile Laser Scanning and its Feasibility for Environmental Mapping https://aaltodoc.aalto.fi/handle/123456789/16212

Benchmarking of terrestrial laser scanning methods: Test datasets available

FGI’s work on benchmarking of terrestrial laser scanning (TLS) methods for forestry applications progresses as planned, and new test datasets have been released in February 2015. More than 10 international groups have already downloaded the test data and more are encouraged to join. The test data can be obtained from the ftp site of the FGI, after sending a request to xinlian.liang@nls.fi or harri.kaartinen@nls.fi.

The EuroSDR project on international benchmarking of terrestrial laser scanning methods for forestry applications is coordinated by the Centre of Excellence FGI group. The project was launched in 2014 in order to gain understanding on an optimum data processing technique for future automated forest plot inventories. The objective of the project is to evaluate the quality, accuracy and feasibility of automatic, semi-automatic or manual tree extraction methods based on high-density TLS data. The data is collected in a test forest, a southern Boreal Forest in Evo, Finland.

The benchmarking project is targeting on the existing and modified algorithms, and manual measurements from the point cloud data. Meanwhile, the project is also open for all techniques that are in the research phase. National mapping agencies, companies, universities and research organizations are all welcomed to participate in the project and to provide the extracted plotwise parameters. In addition to the final report (in the middle of 2016), joint peer-reviewed journal articles on the statistical comparison results will be prepared. All participants will be invited as co-authors/co-writers in all papers.

The distributed data includes one single-scan and one multi-scan dataset for each of the 24 plots. Read more about the data in the project webpage . The TLS data are exclusively used for this project before the publication of the final project report. After that, the point cloud data will be free of use for non-commercial purposes.

1_MS_isometric

Picture: Multi-scan Terrestrial laser scanning data of a test plot 3D (Picture: Jiri Pyörälä)

More information

Xinlian Liang xinlian.liang(a)nls.fi, Harri Kaartinen harri.kaartinen(a)nls.fi

Project webpage: http://www.eurosdr.net/research/project/project-benchmarking-terrestrial-laser-scanning-forestry-applications