scholarly journals Adaptive Framework for the Delineation of Homogeneous Forest Areas Based on LiDAR Points

2019 ◽  
Vol 11 (2) ◽  
pp. 189 ◽  
Author(s):  
Moritz Bruggisser ◽  
Markus Hollaus ◽  
Di Wang ◽  
Norbert Pfeifer
Keyword(s):  
Laser Scanning ◽  
Water Cycle ◽  
Canopy Structure ◽  
Point Clouds ◽  
Forest Patches ◽  
Forest Patch ◽  
Flexible Framework ◽  
Foliage Density ◽  
The One ◽  
Forest Conditions

We propose a flexible framework for automated forest patch delineations that exploits a set of canopy structure features computed from airborne laser scanning (ALS) point clouds. The approach is based on an iterative subdivision of the point cloud using k-means clustering followed by an iterative merging step to tackle oversegmentation. The framework can be adapted for different applications by selecting relevant input features that best measure the intended homogeneity. In our study, the performance of the segmentation framework was tested for the delineation of forest patches with a homogeneous canopy height structure on the one hand and with similar water cycle conditions on the other. For the latter delineation, canopy components that impact interception and evapotranspiration were used, and the delineation was mainly driven by leaf area, tree functional type, and foliage density. The framework was further tested on two scenes covering a variety of forest conditions and topographies. We demonstrate that the delineated patches capture well the spatial distributions of relevant canopy features that are used for defining the homogeneity. The consistencies range from R 2 = 0 . 84 to R 2 = 0 . 86 and from R 2 = 0 . 80 to R 2 = 0 . 91 for the most relevant features in the delineation of patches with similar height structure and water cycle conditions, respectively.

scholarly journals How Much of a Historic Town Can Be Mapped by a Terrestrial Laser Scanner within a Working Day? - A Single Touch Workflow

2017 ◽  
Vol 1 (2) ◽  
pp. 239-250
Author(s):  
Christoph Fürst ◽  
Nikolaus Studnicka ◽  
Martin Pfennigbauer
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Urban Environments ◽  
Terrestrial Laser Scanner ◽  
Single Operator ◽  
Working Day ◽  
The One ◽  
3D Information

Downtown Vienna with its world-famous cultural sites and architectural features is most definitely worth conservation. One way to archive at least a digital 3D imprint is laser scanning. While urban mapping with airborne or mobile laser scanning is fast and efficient, the resulting point clouds might not have the required resolution or might experience gaps due to shadowing. Terrestrial laser scanning has the potential to overcome these limitations. However, it has long been considered time-consuming and labour-intensive both while capturing and also while processing the data.In order to challenge this, we performed a field test with the new RIEGL VZ-400i terrestrial laser scanner. For eight hours, in the night from 2nd to 3rd of June 2016, one single operator employed the instrument throughout the city center of Vienna. He managed to take 514 high-resolution laser scans with approximately 9m between the scan positions.The data acquired in the course of this test impressively demonstrates the potential of state-of-the-art terrestrial laser scanning to preserve detailed 3D-information of urban environments within limited amount of time. This paper describes the complete workflow from the one touch operation in the field up to the automatic registration process of the collected laser scans.     

scholarly journals EVALUATION OF VERTICAL LACUNARITY PROFILES IN FORESTED AREAS USING AIRBORNE LASER SCANNING POINT CLOUDS

2016 ◽  
Vol III-8 ◽  
pp. 93-99
Author(s):  
B. Székely ◽  
A. Kania ◽  
T. Standovár ◽  
H. Heilmeier
Keyword(s):  
Laser Scanning ◽  
Dynamic Range ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Point Clouds ◽  
Reference Points ◽  
Airborne Laser Scanning ◽  
Topographic Effects ◽  
Airborne Laser ◽  
Forested Areas

The horizontal variation and vertical layering of the vegetation are important properties of the canopy structure determining the habitat; three-dimensional (3D) distribution of objects (shrub layers, understory vegetation, etc.) is related to the environmental factors (e.g., illumination, visibility). It has been shown that gaps in forests, mosaic-like structures are essential to biodiversity; various methods have been introduced to quantify this property. As the distribution of gaps in the vegetation is a multi-scale phenomenon, in order to capture it in its entirety, scale-independent methods are preferred; one of these is the calculation of lacunarity. <br><br> We used Airborne Laser Scanning point clouds measured over a forest plantation situated in a former floodplain. The flat topographic relief ensured that the tree growth is independent of the topographic effects. The tree pattern in the plantation crops provided various quasi-regular and irregular patterns, as well as various ages of the stands. The point clouds were voxelized and layers of voxels were considered as images for two-dimensional input. These images calculated for a certain vicinity of reference points were taken as images for the computation of lacunarity curves, providing a stack of lacunarity curves for each reference points. These sets of curves have been compared to reveal spatial changes of this property. As the dynamic range of the lacunarity values is very large, the natural logarithms of the values were considered. Logarithms of lacunarity functions show canopy-related variations, we analysed these variations along transects. The spatial variation can be related to forest properties and ecology-specific aspects.

scholarly journals FOREST INVENTORY ATTRIBUTE ESTIMATION USING AIRBORNE LASER SCANNING, AERIAL STEREO IMAGERY, RADARGRAMMETRY AND INTERFEROMETRY–FINNISH EXPERIENCES OF THE 3D TECHNIQUES

2015 ◽  
Vol II-3/W4 ◽  
pp. 63-69 ◽  
Author(s):  
M. Holopainen ◽  
M. Vastaranta ◽  
M. Karjalainen ◽  
K. Karila ◽  
S. Kaasalainen ◽  
...  
Keyword(s):  
Forest Inventory ◽  
Laser Scanning ◽  
Mixed Forest ◽  
Point Clouds ◽  
Airborne Laser Scanning ◽  
Current Status ◽  
Airborne Laser ◽  
Stereo Imagery ◽  
Sar Data ◽  
Forest Conditions

Three-dimensional (3D) remote sensing has enabled detailed mapping of terrain and vegetation heights. Consequently, forest inventory attributes are estimated more and more using point clouds and normalized surface models. In practical applications, mainly airborne laser scanning (ALS) has been used in forest resource mapping. The current status is that ALS-based forest inventories are widespread, and the popularity of ALS has also raised interest toward alternative 3D techniques, including airborne and spaceborne techniques. Point clouds can be generated using photogrammetry, radargrammetry and interferometry. Airborne stereo imagery can be used in deriving photogrammetric point clouds, as very-high-resolution synthetic aperture radar (SAR) data are used in radargrammetry and interferometry. ALS is capable of mapping both the terrain and tree heights in mixed forest conditions, which is an advantage over aerial images or SAR data. However, in many jurisdictions, a detailed ALS-based digital terrain model is already available, and that enables linking photogrammetric or SAR-derived heights to heights above the ground. In other words, in forest conditions, the height of single trees, height of the canopy and/or density of the canopy can be measured and used in estimation of forest inventory attributes. In this paper, first we review experiences of the use of digital stereo imagery and spaceborne SAR in estimation of forest inventory attributes in Finland, and we compare techniques to ALS. In addition, we aim to present new implications based on our experiences.

scholarly journals Evaluation of Forest Edge Structure and Stability in Peri-Urban Forests

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 338
Author(s):  
David Hladnik ◽  
Andrej Kobler ◽  
Janez Pirnat
Keyword(s):  
Urban Forest ◽  
Residential Buildings ◽  
Canopy Structure ◽  
Urban Forests ◽  
Forest Edge ◽  
Canopy Height ◽  
Forest Edges ◽  
Forest Patches ◽  
Forest Patch ◽  
Edge Structure

In the presented research, we studied the forest edge structure of urban and peri-urban forests on the outskirts of Ljubljana (Slovenia) consisting of a number of patches covering the collective surface of 1884 ha. They differ from each other according to the degree of fragmentation and by the share of the interior forest area. On the basis of LiDAR data, we conducted an analysis of the edges of the persistent forest patches and estimated them with regard to the land use they bordered on. The horizontal estimation of forest edges and the changes of forest edges, in the last decades, were estimated using digital orthophoto images of cyclic aerial surveys of Slovenia, from 1975 to 2018. The data, provided by LiDAR, were used to obtain an accurate estimate of forest edges and the metrics of their vertical canopy structure. On the basis of the canopy height model (CHM), we determined the height classes, the heights of the tallest trees, and indices of canopy height diversity (CHD) as variables subjected to a k-means cluster analysis. To determine the forest edge and trees stability, their heights and diameters at breast height (DBH) were measured and their canopy length and h/d (height/diameter) dimension ratios were estimated. In the study area of the Golovec forest patch, more than half of the forest edge segments (56%) border on residential buildings. After the construction of buildings, 54% of the newly formed forest edges developed a high and steep structure. Unfavorable h/d dimension ratio was estimated for 16% of trees, more among the coniferous than among the deciduous trees. Similar characteristics of newly formed forest edges bordering on built-up areas were determined in other sub-urban forest patches, despite the smaller share of such forest edges (19% and 10%, respectively). Tools and methods presented in the research enable the implementation of concrete silvicultural practices in a realistic time period and extend to ensure that adequate forestry measures are taken to minimize possible disturbances.

scholarly journals EVALUATION OF VERTICAL LACUNARITY PROFILES IN FORESTED AREAS USING AIRBORNE LASER SCANNING POINT CLOUDS

2016 ◽  
Vol III-8 ◽  
pp. 93-99
Author(s):  
B. Székely ◽  
A. Kania ◽  
T. Standovár ◽  
H. Heilmeier
Keyword(s):  
Laser Scanning ◽  
Dynamic Range ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Point Clouds ◽  
Reference Points ◽  
Airborne Laser Scanning ◽  
Topographic Effects ◽  
Airborne Laser ◽  
Forested Areas

The horizontal variation and vertical layering of the vegetation are important properties of the canopy structure determining the habitat; three-dimensional (3D) distribution of objects (shrub layers, understory vegetation, etc.) is related to the environmental factors (e.g., illumination, visibility). It has been shown that gaps in forests, mosaic-like structures are essential to biodiversity; various methods have been introduced to quantify this property. As the distribution of gaps in the vegetation is a multi-scale phenomenon, in order to capture it in its entirety, scale-independent methods are preferred; one of these is the calculation of lacunarity. &lt;br&gt;&lt;br&gt; We used Airborne Laser Scanning point clouds measured over a forest plantation situated in a former floodplain. The flat topographic relief ensured that the tree growth is independent of the topographic effects. The tree pattern in the plantation crops provided various quasi-regular and irregular patterns, as well as various ages of the stands. The point clouds were voxelized and layers of voxels were considered as images for two-dimensional input. These images calculated for a certain vicinity of reference points were taken as images for the computation of lacunarity curves, providing a stack of lacunarity curves for each reference points. These sets of curves have been compared to reveal spatial changes of this property. As the dynamic range of the lacunarity values is very large, the natural logarithms of the values were considered. Logarithms of lacunarity functions show canopy-related variations, we analysed these variations along transects. The spatial variation can be related to forest properties and ecology-specific aspects.

scholarly journals AUTOMATED CALIBRATION OF FEM MODELS USING LIDAR POINT CLOUDS

2018 ◽  
Vol XLII-2 ◽  
pp. 969-974
Author(s):  
B. Riveiro ◽  
G. Cubreiro ◽  
B. Conde ◽  
M. Cabaleiro ◽  
R. Lindenbergh ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Experimental Tests ◽  
Point Clouds ◽  
Structural Behaviour ◽  
Elastic Parameters ◽  
Structural Element ◽  
Simulation Tools ◽  
Combined Use ◽  
The One ◽  
Behaviour Simulation

In present work it is pretended to estimate elastic parameters of beams through the combined use of precision geomatic techniques (laser scanning) and structural behaviour simulation tools. The study has two aims, on the one hand, to develop an algorithm able to interpret automatically point clouds acquired by laser scanning systems of beams subjected to different load situations on experimental tests; and on the other hand, to minimize differences between deformation values given by simulation tools and those measured by laser scanning. In this way we will proceed to identify elastic parameters and boundary conditions of structural element so that surface stresses can be estimated more easily.

scholarly journals The Potential of Multispectral Imagery and 3D Point Clouds from Unoccupied Aerial Systems (UAS) for Monitoring Forest Structure and the Impacts of Wildfire in Mediterranean-Climate Forests

2021 ◽  
Vol 13 (19) ◽  
pp. 3810
Author(s):  
Sean Reilly ◽  
Matthew L. Clark ◽  
Lisa Patrick Bentley ◽  
Corbin Matley ◽  
Elise Piazza ◽  
...  
Keyword(s):  
Forest Structure ◽  
Laser Scanning ◽  
Vegetation Index ◽  
Canopy Structure ◽  
Point Clouds ◽  
System Structure ◽  
Fuel Load ◽  
Mediterranean Forests ◽  
Generation Process ◽  
3D Point Clouds

Wildfire shapes vegetation assemblages in Mediterranean ecosystems, such as those in the state of California, United States. Successful restorative management of forests in-line with ecologically beneficial fire regimes relies on a thorough understanding of wildfire impacts on forest structure and fuel loads. As these data are often difficult to comprehensively measure on the ground, remote sensing approaches can be used to estimate forest structure and fuel load parameters over large spatial extents. Here, we analyze the capabilities of one such methodology, unoccupied aerial system structure from motion (UAS-SfM) from digital aerial photogrammetry, for mapping forest structure and wildfire impacts in the Mediterranean forests of northern California. To determine the ability of UAS-SfM to map the structure of mixed oak and conifer woodlands and to detect persistent changes caused by fire, we compared UAS-SfM derived metrics of terrain height and canopy structure to pre-fire airborne laser scanning (ALS) measurements. We found that UAS-SfM was able to accurately capture the forest’s upper-canopy structure, but was unable to resolve mid- and below-canopy structure. The addition of a normalized difference vegetation index (NDVI) ground point filter to the DTM generation process improved DTM root-mean-square error (RMSE) by ~1 m with an overall DTM RMSE of 2.12 m. Upper-canopy metrics (max height, 95th percentile height, and 75th percentile height) were highly correlated between ALS and UAS-SfM (r > +0.9), while lower-canopy metrics and metrics of density and vertical variation had little to no similarity. Two years after the 2017 Sonoma County Tubbs fire, we found significant decreases in UAS-SfM metrics of bulk canopy height and NDVI with increasing burn severity, indicating the lasting impact of the fire on vegetation health and structure. These results point to the utility of UAS-SfM as a monitoring tool in Mediterranean forests, especially for post-fire canopy changes and subsequent recovery.

scholarly journals EVALUATION OF MOBILE MAPPING SYSTEMS FOR INDOOR SURVEYS

2020 ◽  
Vol XLIV-4/W1-2020 ◽  
pp. 119-125
Author(s):  
H. Salgues ◽  
H. Macher ◽  
T. Landes
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Mobile Mapping ◽  
Area Of Interest ◽  
3D Point Clouds ◽  
Reliable Assessment ◽  
Acquisition Mode ◽  
The One ◽  
Mobile Mapping Systems ◽  
Mapping Systems

Abstract. With their high recording rate of hundreds of thousands of points acquired per second, speed of execution and a remote acquisition mode, SLAM based mobile mapping systems (MMS) are a very powerful solution for capturing 3D point clouds in real time, simply by walking in the area of interest. Regarding indoor surveys, these MMS have been integrated in handheld or backpack solutions and become fast scanning sensors. Despite their advantages, the geometric accuracy of 3D point clouds guaranteed with these sensors is lower than the one reachable with static TLS. In this paper the effectiveness of two recent mobile mapping systems namely the GeoSLAM ZEB-REVO RT and the more recent GreenValley LiBackPack C50 is investigated for indoor surveys. In order to perform a reliable assessment study, several datasets produced with each sensor are compared to the high-cost georeferenced point cloud obtained with static laser scanning target-based technique.

The Belt and Road Initiative and Sino-Russian economic cooperation: Is there one more chance for us?

2019 ◽  
pp. 47-71
Author(s):  
Petr M. Mozias
Keyword(s):  
Regional Integration ◽  
Raw Materials ◽  
Belt And Road Initiative ◽  
Stage Of Development ◽  
Belt And Road ◽  
Flexible Framework ◽  
The One ◽  
International Transactions ◽  
The Belt And Road ◽  
Current Stage

China’s Belt and Road Initiative could be treated ambiguously. On the one hand, it is intended to transform the newly acquired economic potential of that country into its higher status in the world. China invites a lot of nations to build up gigantic transit corridors by joint efforts, and doing so it applies productively its capital and technologies. International transactions in RMB are also being expanded. But, on the other hand, the Belt and Road Initiative is also a necessity for China to cope with some evident problems of its current stage of development, such as industrial overcapacity, overdependence on imports of raw materials from a narrow circle of countries, and a subordinate status in global value chains. For Russia participation in the Belt and Road Initiative may be fruitful, since the very character of that project provides us with a space to manoeuvre. By now, Russian exports to China consist primarily of fuels and other commodities. More active industrial policy is needed to correct this situation . A flexible framework of the Belt and Road Initiative is more suitable for this objective to be achieved, rather than traditional forms of regional integration, such as a free trade zone.

scholarly journals Disturbance Analysis in the Classification of Objects Obtained from Urban LiDAR Point Clouds with Convolutional Neural Networks

2021 ◽  
Vol 13 (11) ◽  
pp. 2135
Author(s):  
Jesús Balado ◽  
Pedro Arias ◽  
Henrique Lorenzo ◽  
Adrián Meijide-Rodríguez
Keyword(s):  
Laser Scanning ◽  
Ambient Noise ◽  
Point Clouds ◽  
Density Variation ◽  
Density Reduction ◽  
Manual Intervention ◽  
Point Density ◽  
Disturbance Analysis ◽  
Street Furniture

Mobile Laser Scanning (MLS) systems have proven their usefulness in the rapid and accurate acquisition of the urban environment. From the generated point clouds, street furniture can be extracted and classified without manual intervention. However, this process of acquisition and classification is not error-free, caused mainly by disturbances. This paper analyses the effect of three disturbances (point density variation, ambient noise, and occlusions) on the classification of urban objects in point clouds. From point clouds acquired in real case studies, synthetic disturbances are generated and added. The point density reduction is generated by downsampling in a voxel-wise distribution. The ambient noise is generated as random points within the bounding box of the object, and the occlusion is generated by eliminating points contained in a sphere. Samples with disturbances are classified by a pre-trained Convolutional Neural Network (CNN). The results showed different behaviours for each disturbance: density reduction affected objects depending on the object shape and dimensions, ambient noise depending on the volume of the object, while occlusions depended on their size and location. Finally, the CNN was re-trained with a percentage of synthetic samples with disturbances. An improvement in the performance of 10–40% was reported except for occlusions with a radius larger than 1 m.

Sign in / Sign up

Export Citation Format

Share Document