Holger Weinacker

Holger Weinacker
University of Freiburg | Albert-Ludwigs-Universität Freiburg · Faculty of Forest and Environmental Sciences

Dr.-Ing.

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53
Publications
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2,244
Citations

Publications

Publications (53)
Article
Full-text available
Arnica montana L. is a medicinal plant with significant conservation importance. It is crucial to monitor this species, ensuring its sustainable harvesting and management. The aim of this study is to develop a practical system that can effectively detect A. montana inflorescences utilizing unmanned aerial vehicles (UAVs) with RGB sensors (red–green...
Article
To reduce the cost of manually annotating training data for supervised classifiers, we propose an automated approach to extract training data of urban objects in six classes: buildings, fences, man-made poles, vegetation, vehicles, and low objects. In this study, two segmentation algorithms are firstly implemented to generate meaningful objects fro...
Article
Full-text available
Unoccupied aerial vehicles (UAV) with RGB-cameras are affordable and versatile devices for the generation of a series of remote sensing products that can be used for forest inventory tasks, such as creating high-resolution orthomosaics and canopy height models. The latter may serve purposes including tree species identification, forest damage asses...
Article
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An accurate understanding of urban objects is critical for urban modeling, intelligent infrastructure planning and city management. The semantic segmentation of light detection and ranging (LiDAR) point clouds is a fundamental approach for urban scene analysis. Over the last years, several methods have been developed to segment urban furniture with...
Article
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The detection of individual trees in a larch plantation could improve the management efficiency and production prediction. This study introduced a two-stage individual tree crown (ITC) segmentation method for airborne light detection and ranging (LiDAR) point clouds, focusing on larch plantation forests with different stem densities. The two-stage...
Article
Land-cover mapping (LCM) at a fine scale would be useful for forest management across heterogeneous natural landscapes. However, the heterogeneity of land covers at such scales results in complex spectral and textural properties that hinder the applicability of LCM. Besides, the method suffers from, e.g. inconsistent representation of different lan...
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Accurate and updated knowledge of forest tree heights is fundamental in the context of forest management. However, measuring canopy height over large forest areas using traditional inventory techniques is laborious, timeconsuming and excessively expensive. In this study, image-based point clouds produced from stereo aerial photographs (AP) were use...
Article
Remote sensing-based timber volume estimation is key for modelling the regional potential, accessibility and price of lignocellulosic raw material for an emerging bioeconomy. We used a unique wall-to-wall air- borne LiDAR dataset and Landsat 7 satellite images in combination with terrestrial inventory data derived from the National Forest Inventory...
Conference Paper
Full-text available
Highlights: Tree top detection using laser scanner data is very important when tree modeling and measurement are concerned. However, software used for this purpose are expensive and scarce. This project aimed to assess Scikit-image for tree local maxima detection. Scikit-image is a Python based package using Numpy and Scipy.
Article
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Airborne laser scanning data and corresponding field data were acquired from boreal forests in Norway and Sweden, coniferous and broadleaved forests in Germany and tropical pulpwood plantations in Brazil. Treetop positions were extracted using six different algorithms developed in Finland, Germany, Norway and Sweden, and the accuracy of tree detect...
Conference Paper
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Within the past decade progress towards automatic recognition of individual trees and their parameters was made in both TLS and ALS-data based algorithms. In this paper we present an approach to combine single trees derived from ALS and TLS-data in order to gain a higher level of information. Therefore, two data sets are used: 1. a set of 3D-stemfi...
Article
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The automatic extraction of single trees from remotely sensed data is approached in numerous studies, but results are still insufficient in areas of dense temperate forest. Common watershed-based algorithms using digital surface models tend to produce erroneous results in difficult constellations because the treetop determination lacks an exact cri...
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This article compares three methods for forest resource estimation based on remote sensing features extracted from Airborne laser scanning and CIR orthophotos. The estimation was made exemplarily for the total stem volume of trees for a given area, measured in cubic metres per hectare [m³ha−1] (as one of the most important quantitative parameters t...
Conference Paper
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In the presented work, single tree detection and shape reconstruction was carried out using full waveform airborne laser scanning (ALS) data. The medium density data was acquired from the mixed forest area in the Rhine valley near Karlsruhe, Germany. Study was conducted in the rectangular plots, each of size 2500 m 2 , containing 12 tree species of...
Conference Paper
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The three-dimensional single tree extraction by applying pattern recognition based modified clustering approach on full waveform normalized raw LIDAR data has been presented in this research work. The LIDAR data of medium density (16 points m -2) was collected in August 2007 from the administrative forest district Hardt, Germany. The total study ar...
Article
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In the past, many algorithms have been applied for three-dimensional (3-D) single tree extraction using Airborne Laser Scanner (ALS) data. Clustering based algorithms are widely used in different applications but rarely being they used in the field of forestry using ALS data as an input. In this paper, a comparative qualitative study was conducted...
Article
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Accurate assessment of timber resources is of great importance for forest management. This article evaluates a combination of airborne laser scanning and color infrared (CIR) orthophotos to estimate the stem volume of forest stands using growth and yield tables recommended for the Federal State of Baden-Württemberg, Germany. The stand height, which...
Article
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A literature review of new publications in the field of 3D data for forest applications shows that the application of airborne laser scanner data (ALS) is in the focus of research today due to its great potential for practical applications. While there is a lot of research carried out to derive forest management parameters based on laser metrics de...
Article
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A full automated classification of tree species was tested on single tree level. This approach intends to classify without any parameter input or predefined knowledge. In the forerun it was therefore necessary to build algorithms which combine the LiDAR data based 2D single tree delineation with the spectral information from colour infrared (CIR) i...
Article
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A whole procedure of fully automatic 3D single tree modelling based on LIDAR point cloud is introduced in the paper. The evaluation of the procedure is then delivered by verifying the modelling results with field collecting data in sample plots. With the procedure, individual trees are extracted not only from the top canopy layer but also from the...
Article
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A procedure for both vertical canopy structure analysis and 3D single tree modelling based on Lidar point cloud is presented in this paper. The whole area of research is segmented into small study cells by a raster net. For each cell, a normalized point cloud whose point heights represent the absolute heights of the ground objects is generated from...
Conference Paper
Full-text available
The purpose of this study is to categorize how different surface model resolutions impact the estimation of trees and forest stands parameters: number of recognized trees, crown area, treetop location and height of single trees. For forest analysis the following models - DSM (Digital Surface Model) and nDSM (normalized Digital Surface Model) were t...
Conference Paper
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Detailed geo-referenced information on the distribution and occurrence of forest and non-forest vegetation is essential for many different disciplines e.g. forestry, nature conservation, agriculture, landscaping and urban planning. This article presents a digital image processing procedure for automated delineation and classification of forest and...
Conference Paper
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Timber Volume is one of the most important quantitative parameters to characterize a forest stand. This article evaluates a combination of Airborne Laser Scanning and GIS data to estimate timber volume of forest stands using standard forestry yield models. The input parameters into the models are the stand height and canopy density which are both d...
Article
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A software program has been developed to generate true orthophotographs using multispectral and lidar data. To accomplish this, the obscured points were first identified in the acquired conventional orthophotographs. Next, the obscured points were replaced with corresponding unobscured points from the neighbouring orthophotographs. Finally, the res...
Article
Full-text available
A procedure for both vertical canopy structure analysis and 3D single tree extraction based on Lidar raw point cloud is presented in this paper. The whole study area is segmented into small study cells by a raster net. For each cell, a normalized point cloud whose point heights represent the absolute heights of the ground objects is generated from...
Article
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Laser scanning provides a good means to collect information on forest stands. This paper presents an approach to delineate single trees automatically in small footprint light detection and ranging (lidar) data in deciduous and mixed temperate forests. In rasterized laser data possible tree tops are detected with a local maximum filter. Afterwards t...
Article
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During the last years the protection of nature has become a very important aspect for interference or structural alterations. It is necessary for all planning, which might have consequences for nature or impairments of nature, to get information about the actual state and the variations of landscape components. A promising field for the extraction...
Conference Paper
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The assessment and visualisation of 3D information has increased its importance tremendously. This is due to the fact that the assessment of 3D information is with development of new measurement technologies of increasing quality and appropriate software makes the processing of 3D information more straightforward. These developments allow better ap...
Conference Paper
Full-text available
Airborne Laser Scanning (ALS), also referred to as LIDAR, is an up-to-date, largely automated method for mapping, GIS data acquisition and topographic feature extraction, which can be used to derive forest inventory variables. Several studies have already shown the capability to accurately estimate important inventory parameters (Weinacker et al. 2...
Article
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Competition for light is the most driving factor for differentiation processes in forest stands. With increasing portion of the sun exposed surface of a single tree's crown photosynthetic activity will increase correspondingly. Thus, trees receiving a high amount of solar radiation will grow faster than more shaded trees. Based on this simple assum...
Article
For a multitude of planning tasks, e.g. planning of power-lines, urban- and landscape planning or for forestry time-consuming on site inventories have to be done and thereby large costs arise. Therefore it is desirable to automate the inventory as far as possible. To make this aim realistic software has been developed, which provide a fundament for...
Article
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Inventories and monitoring systems are important tools for sustainable forest management and for the protection of nature in general. In order to make appropriate management plans, it is important to obtain information about the actual state of the environment and the extent of possible changes. Up until now, forest inventories have been based on t...
Article
A software package has been developed, allowing to visualise simultaneously several data-sets in real-time without the need of special graphic hardware. This is achieved by combining DirectX routines together with methods like CLOD, culling, indicated triangles, ROAM, Quad tree, GeoMorphing and Geo-Mipmapping. This has been done within the framewor...
Article
The purpose of this study was to test a method for delineating individual tree crowns using a fully automated object-based pattern recognition methodology. The study material included small-footprint time-of-flight laser scanner data acquired over the Norway spruce (Picea abies) and European beech (Fagus sylvatica) dominated forests of the Bavarian...
Article
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Ecological analysis and forest planning need sophisticated informations about the structures of forests. In recent years new sensor systems like laserscanner and digital airborne cameras emerged on the marked which fulfil the high requirements for forest applications. Also new methods for automated delineation and feature extraction of individual t...
Article
Full-text available
During the last decade the protection of nature has become a very important aspect for interfer-ence or structural alterations. It is necessary for all planning, which might have consequences for nature or impairments of nature, to get information about the actual state and the variations of landscape components. A promising field for the extractio...
Article
Full-text available
Da die Datenerhebung für die meisten dieser Verfahren manuell erfolgt und damit sehr zeit- bzw. kostenintensiv ist, besteht ein großes Interesse daran, die Arbeitsabläufe zu automatisieren. Die im Bereich des Laserscannings stetig voranschreitenden Entwicklungen im Hard- und Softwarebereich lassen diese Technologie auch im Bereich des Umweltmonitor...

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