scholarly journals On the utilization of novel spectral laser scanning for three-dimensional classification of vegetation elements

2018 ◽  
Vol 8 (2) ◽  
pp. 20170039 ◽  
Author(s):  
Zhan Li ◽  
Michael Schaefer ◽  
Alan Strahler ◽  
Crystal Schaaf ◽  
David Jupp
Keyword(s):  
Laser Scanning ◽  
Spatial Information ◽  
Information Source ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Biochemical Properties ◽  
Dual Wavelength ◽  
Wavelength Scanning ◽  
Spatial Attributes

The Dual-Wavelength Echidna Lidar (DWEL), a full waveform terrestrial laser scanner (TLS), has been used to scan a variety of forested and agricultural environments. From these scanning campaigns, we summarize the benefits and challenges given by DWEL's novel coaxial dual-wavelength scanning technology, particularly for the three-dimensional (3D) classification of vegetation elements. Simultaneous scanning at both 1064 nm and 1548 nm by DWEL instruments provides a new spectral dimension to TLS data that joins the 3D spatial dimension of lidar as an information source. Our point cloud classification algorithm explores the utilization of both spectral and spatial attributes of individual points from DWEL scans and highlights the strengths and weaknesses of each attribute domain. The spectral and spatial attributes for vegetation element classification each perform better in different parts of vegetation (canopy interior, fine branches, coarse trunks, etc.) and under different vegetation conditions (dead or live, leaf-on or leaf-off, water content, etc.). These environmental characteristics of vegetation, convolved with the lidar instrument specifications and lidar data quality, result in the actual capabilities of spectral and spatial attributes to classify vegetation elements in 3D space. The spectral and spatial information domains thus complement each other in the classification process. The joint use of both not only enhances the classification accuracy but also reduces its variance across the multiple vegetation types we have examined, highlighting the value of the DWEL as a new source of 3D spectral information. Wider deployment of the DWEL instruments is in practice currently held back by challenges in instrument development and the demands of data processing required by coaxial dual- or multi-wavelength scanning. But the simultaneous 3D acquisition of both spectral and spatial features, offered by new multispectral scanning instruments such as the DWEL, opens doors to study biophysical and biochemical properties of forested and agricultural ecosystems at more detailed scales.

scholarly journals Segmentation and Multi-Scale Convolutional Neural Network-Based Classification of Airborne Laser Scanner Data

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3347 ◽  
Author(s):  
Zhishuang Yang ◽  
Bo Tan ◽  
Huikun Pei ◽  
Wanshou Jiang
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Region Growing ◽  
Point Clouds ◽  
Classification Method ◽  
Multi Scale ◽  
Airborne Laser

The classification of point clouds is a basic task in airborne laser scanning (ALS) point cloud processing. It is quite a challenge when facing complex observed scenes and irregular point distributions. In order to reduce the computational burden of the point-based classification method and improve the classification accuracy, we present a segmentation and multi-scale convolutional neural network-based classification method. Firstly, a three-step region-growing segmentation method was proposed to reduce both under-segmentation and over-segmentation. Then, a feature image generation method was used to transform the 3D neighborhood features of a point into a 2D image. Finally, feature images were treated as the input of a multi-scale convolutional neural network for training and testing tasks. In order to obtain performance comparisons with existing approaches, we evaluated our framework using the International Society for Photogrammetry and Remote Sensing Working Groups II/4 (ISPRS WG II/4) 3D labeling benchmark tests. The experiment result, which achieved 84.9% overall accuracy and 69.2% of average F1 scores, has a satisfactory performance over all participating approaches analyzed.

scholarly journals 3D MODELS OF OBJECTS IN PROCESS OF RECONSTRUCTION

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Jovana Radović
Keyword(s):  
Laser Scanning ◽  
Laser System ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Terrestrial Laser Scanning ◽  
3D Models ◽  
Terrestrial Laser Scanner ◽  
Accurate Data ◽  
Final Model ◽  
Airborne Laser

Within the last years terrestrial and airborne laser scanning has become a powerful technique for fast and efficient three-dimensional data acquisition of different kinds of objects. Airborne laser system (LiDAR) collects accurate georeferenced data of extremely large areas very quickly while the terrestrial laser scanner produces dense and geometrically accurate data. The combination of these two segments of laser scanning provides different areas of application. One of the applications is in the process of reconstruction of objects. Objects recorded with laser scanning technology and transferred into the final model represent the basis for building an object as it was original. In this paper, there will be shown two case studies based on usage of airborne and terrestrial laser scanning and processing of the data collected by them.

scholarly journals Leveraging OSM and GEOBIA to Create and Update Forest Type Maps

2020 ◽  
Vol 9 (9) ◽  
pp. 499
Author(s):  
Melanie Brauchler ◽  
Johannes Stoffels
Keyword(s):  
Data Model ◽  
Classification Accuracy ◽  
Sustainable Forest Management ◽  
Spatial Information ◽  
Forest Type ◽  
Information Source ◽  
Essential Element ◽  
Aerial Imagery ◽  
Leaf Type

Up-to-date information about the type and spatial distribution of forests is an essential element in both sustainable forest management and environmental monitoring and modelling. The OpenStreetMap (OSM) database contains vast amounts of spatial information on natural features, including forests (landuse=forest). The OSM data model includes describing tags for its contents, i.e., leaf type for forest areas (i.e., leaf_type=broadleaved). Although the leaf type tag is common, the vast majority of forest areas are tagged with the leaf type mixed, amounting to a total area of 87% of landuse=forests from the OSM database. These areas comprise an important information source to derive and update forest type maps. In order to leverage this information content, a methodology for stratification of leaf types inside these areas has been developed using image segmentation on aerial imagery and subsequent classification of leaf types. The presented methodology achieves an overall classification accuracy of 85% for the leaf types needleleaved and broadleaved in the selected forest areas. The resulting stratification demonstrates that through approaches, such as that presented, the derivation of forest type maps from OSM would be feasible with an extended and improved methodology. It also suggests an improved methodology might be able to provide updates of leaf type to the OSM database with contributor participation.

scholarly journals A Model-Dependent Method for Monitoring Subtle Changes in Vegetation Height in the Boreal–Alpine Ecotone Using Bi-Temporal, Three Dimensional Point Data from Airborne Laser Scanning

2019 ◽  
Vol 11 (15) ◽  
pp. 1804
Author(s):  
Erik Næsset ◽  
Terje Gobakken ◽  
Ronald E. McRoberts
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Tree Height ◽  
Residual Variance ◽  
Tree Line ◽  
Average Growth ◽  
Vegetation Height ◽  
Airborne Laser ◽  
Height Change

The boreal tree line is in many places expected to advance upwards into the mountains due to climate change. This study aimed to develop a general method for estimation of vegetation height change in general, and change in tree height more specifically, for small geographical domains utilizing bi-temporal airborne laser scanner (ALS) data. The domains subject to estimation may subsequently be used to monitor vegetation and tree height change with detailed temporal and geographical resolutions. A method was developed with particular focus on statistically rigorous estimators of uncertainty for change estimates. The method employed model-dependent statistical inference. The method was demonstrated in a 12 ha study site in a boreal–alpine tree line in southeastern Norway, in which 316 trees were measured on the ground in 2006 and 2012 and ALS data were acquired in two temporally coincident campaigns. The trees ranged from 0.11 m to 5.20 m in height. Average growth in height was 0.19 m. Regression models were used to predict and estimate change. By following the area-based approach, predictions were produced for every individual 2 m2 population element that tessellated the study area. Two demonstrations of the method are provided in which separate height change estimates were calculated for domains of size 1.5 ha or greater. Differences in height change estimates among such small domains illustrate how change patterns may vary over the landscape. Model-dependent mean square error estimates for the height change estimators that accounted for (1) model parameter uncertainty, (2) residual variance, and (3) residual covariance are provided. Findings suggested that the two latter sources of uncertainty could be ignored in the uncertainty analysis. The proposed estimators are likely to work well for estimation of differences in height change along a gradient of small monitoring units, like the 1.5 ha cells used for demonstration purposes, and thus may potentially be used to monitor tree line migration over time.

3D Laser Scanner and its Application in Engineering Survey

2013 ◽  
Vol 671-674 ◽  
pp. 2111-2114
Author(s):  
Yan Ping Feng ◽  
Wei Guo Li ◽  
Li Bing Yang ◽  
Yan Li Gao ◽  
Wen Bin Li
Keyword(s):  
Laser Scanning ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Target Object ◽  
Scanning System ◽  
3 Dimensional ◽  
Working Principle ◽  
Laser Scanning System ◽  
Three Dimensional Space

3D laser scanning system is to use laser ranging principle to record intensively the 3D coordinates, reflectivity and texture information on the surface of the target object. It makes a real record of the three-dimensional space, which makes traditional measurement be released from the limit that couldn’t be exceeded in the past, and let the measurement precision up to a new level. At the same time, it has provided extensive researches with better help than ever. This paper mainly discusses the characteristics, working principle, application and future development of the ground 3 dimensional laser scanner.

Sex Discrimination: How Do We Tell the Difference between Male and Female Faces?

Perception ◽  
1993 ◽  
Vol 22 (2) ◽  
pp. 131-152 ◽  
Author(s):  
Vicki Bruce ◽  
A Mike Burton ◽  
Elias Hanna ◽  
Pat Healey ◽  
Oli Mason ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Sex Discrimination ◽  
Shape From Shading ◽  
Skin Texture ◽  
Facial Hair ◽  
Eyes Closed ◽  
The Face ◽  
The Difference

People are remarkably accurate (approaching ceiling) at deciding whether faces are male or female, even when cues from hairstyle, makeup, and facial hair are minimised. Experiments designed to explore the perceptual basis of our ability to categorise the sex of faces are reported. Subjects were considerably less accurate when asked to judge the sex of three-dimensional (3-D) representations of faces obtained by laser-scanning, compared with a condition where photographs were taken with hair concealed and eyes closed. This suggests that cues from features such as eyebrows, and skin texture, play an important role in decisionmaking. Performance with the laser-scanned heads remained quite high with 3/4-view faces, where the 3-D shape of the face should be easiest to see, suggesting that the 3-D structure of the face is a further source of information contributing to the classification of its sex. Performance at judging the sex from photographs (with hair concealed) was disrupted if the photographs were inverted, which implies that the superficial cues contributing to the decision are not processed in a purely ‘local’ way. Performance was also disrupted if the faces were shown in photographic negatives, which is consistent with the use of 3-D information, since negation probably operates by disrupting the computation of shape from shading. In 3-D, the ‘average’ male face differs from the ‘average’ female face by having a more protuberant nose/brow and more prominent chin/jaw. The effects of manipulating the shapes of the noses and chins of the laser-scanned heads were assessed and significant effects of such manipulations on the apparent masculinity or femininity of the heads were revealed. It appears that our ability to make this most basic of facial categorisations may be multiply determined by a combination of 2-D, 3-D, and textural cues and their interrelationships.

scholarly journals TRIANGULATION AND TIME-OF-FLIGHT BASED 3D DIGITISATION TECHNIQUES OF CULTURAL HERITAGE STRUCTURES

2021 ◽  
Vol XLIII-B2-2021 ◽  
pp. 825-830
Author(s):  
C. Altuntas
Keyword(s):  
Cultural Heritage ◽  
Laser Scanning ◽  
Low Cost ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Time Of Flight ◽  
Cost Effective ◽  
Cloud Data ◽  
Dense Point

Abstract. This study aims to introduce triangulation and ToF measurement techniques used in three-dimensional modelling of cultural heritages. These measurement techniques are traditional photogrammetry, SfM approach, laser scanning and time-of-flight camera. The computer based approach to photogrammetric measurement that is named SfM creates dense point cloud data in a short time. It is low-cost and very easy to application. However traditional photogrammetry needs a huge effort for creating 3D wire-frame model. On the other hand active measurement techniques such as terrestrial laser scanner and time-of-flight camera have also been used in three-dimensional modelling for more than twenty years. Each one has specific accuracy and measurement effectiveness. The large or small structures have different characters, and require proper measurement configurations. In this study, after these methods are introduced, their superior and weak properties in cultural heritage modelling to make high accuracy, high density and labour and cost effective measurement.

scholarly journals FAST AND ROBUST SEGMENTATION AND CLASSIFICATION FOR CHANGE DETECTION IN URBAN POINT CLOUDS

2016 ◽  
Vol XLI-B3 ◽  
pp. 693-699 ◽  
Author(s):  
X. Roynard ◽  
J.-E. Deschaud ◽  
F. Goulette
Keyword(s):  
Change Detection ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Region Growing ◽  
Point Clouds ◽  
Object Class ◽  
Robust Segmentation ◽  
Street Furniture ◽  
Fast Region

Change detection is an important issue in city monitoring to analyse street furniture, road works, car parking, etc. For example, parking surveys are needed but are currently a laborious task involving sending operators in the streets to identify the changes in car locations. In this paper, we propose a method that performs a fast and robust segmentation and classification of urban point clouds, that can be used for change detection. We apply this method to detect the cars, as a particular object class, in order to perform parking surveys automatically. A recently proposed method already addresses the need for fast segmentation and classification of urban point clouds, using elevation images. The interest to work on images is that processing is much faster, proven and robust. However there may be a loss of information in complex 3D cases: for example when objects are one above the other, typically a car under a tree or a pedestrian under a balcony. In this paper we propose a method that retain the three-dimensional information while preserving fast computation times and improving segmentation and classification accuracy. It is based on fast region-growing using an octree, for the segmentation, and specific descriptors with Random-Forest for the classification. Experiments have been performed on large urban point clouds acquired by Mobile Laser Scanning. They show that the method is as fast as the state of the art, and that it gives more robust results in the complex 3D cases.

scholarly journals High resolution digital 3D modelling of subsurface morphological structures of Koutouki Cave, Greece

2020 ◽  
Vol 49 (2-3) ◽  
Author(s):  
Aliki Konsolaki ◽  
Emmanuel Vassilakis ◽  
Leonidas Gouliotis ◽  
Georgios Kontostavlos ◽  
Vassilis Giannopoulos
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Open Space ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Column Height ◽  
Indoor Environments ◽  
Terrain Analysis ◽  
Dimensional Measurements ◽  
Quantification Analysis

Remote sensing techniques and laser scanning technology have given us the opportunity to study indoor environments, such as caves, with their complex and unique morphology. In the presented case study, we used a handheld laser scanner for acquiring points with projected coordinate information (X, Y, Z) covering the entire show cave of Koutouki; including its hidden passages and dark corners. The point cloud covers the floor, the walls, and the roof of the cave, as well as the stalactites, stalagmites and the connected columns that constitute the decoration of the cave. The absolute and exact placement of the point cloud within a geographic reference frame gives us the opportunity for three-dimensional measurements and detailed visualization of the subsurface structures. Using open - source software, we managed to make a quantification analysis of the terrain and generated morphological and geometric features of the speleothems. We identified 55 columns by using digital terrain analysis and processed them statistically in order to correlate them to the frame of the cave development. The parameters that derived are the contours, each column height, the speleothem geometry and volume, as well as the volume of the open space cavity. We argue that by the demonstrated methodology, it is possible to identify with high accuracy and detail: the geomorphological features of a cave, an estimate of the speleogenesis, and the ability to monitor the evolution of a karstic system.Key words: cave, laser scanner, 3D representation, speleothems, SLAM.  

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