scholarly journals Metrics of Coral Reef Structural Complexity Extracted from 3D Mesh Models and Digital Elevation Models

2020 ◽  
Vol 12 (17) ◽  
pp. 2676 ◽  
Author(s):  
Atsuko Fukunaga ◽  
John H. R. Burns
Keyword(s):  
Coral Reef ◽  
Digital Elevation Models ◽  
Three Dimensional ◽  
Structural Complexity ◽  
3D Models ◽  
3D Reconstructions ◽  
3D Mesh ◽  
Coral Colony ◽  
Digital Elevation ◽  
Mesh Models

Underwater photogrammetry has been increasingly used in coral-reef research in recent years. Habitat metrics extracted from resulting three-dimensional (3D) reconstructions can be used to examine associations between the structural complexity of the reef habitats and the distribution of reef organisms. We created simulated 3D models of bare surface structures and 3D reconstructions of coral morphologies to investigate the behavior of various habitat metrics that were extracted from both Digital Elevation Models (DEMs) and 3D mesh models. Analyzing the resulting values provided us with important insights into how these metrics would compare with one another in the characterization of coral-reef habitats. Surface complexity (i.e., reef rugosity), fractal dimension extracted from DEMs and vector dispersion obtained from 3D mesh models exhibited consistent patterns in the ranking of structural complexity among the simulated bare surfaces and coral morphologies. The vector ruggedness measure obtained from DEMs at three different resolutions of 1, 2, and 4 cm effectively captured differences in the structural complexity among different coral morphologies. Profile curvature and planform curvature, on the other hand, were better suited to capture the structural complexity derived from surface topography such as walls and overhanging ledges. Our results indicate that habitat metrics extracted from DEMs are generally suitable when characterizing a relatively large plot of a coral reef captured from an overhead planar angle, while the 3D metric of vector dispersion is suitable when characterizing a coral colony or a relatively small plot methodically captured from various angles.

scholarly journals Determination of sex-related differences based on 3D reconstruction of the chinchilla (Chinchilla lanigera) vertebral column from MDCT scans

2017 ◽  
Vol 62 (No. 4) ◽  
pp. 204-210 ◽  
Author(s):  
S. Ozkadif ◽  
E. Eken ◽  
MO Dayan ◽  
K. Besoluk
Keyword(s):  
Surface Area ◽  
Body Length ◽  
Vertebral Body ◽  
Vertebral Column ◽  
Three Dimensional ◽  
3D Models ◽  
3D Modelling ◽  
3D Reconstructions ◽  
Thoracic Part

This study was undertaken to obtain and analyse, on the basis of sex, three-dimensional (3D) reconstructions obtained by a 3D computer program from two-dimensional (2D) vertebral column sections taken by multidetector computed tomography (MDCT) images, in the chinchilla. A total of 16 adult chinchillas (Chinchilla lanigera) of both sexes were used. The MDCT images were taken under general anaesthesia, and were then transferred to a personal computer on which 3D reconstructions were carried out using a 3D modelling program (Mimics 13.1). The volume, surface area and vertebral body length of each vertebra (except caudal region) forming the vertebral column were measured from the 3D models created. The ratios (in percentage) of the measurements of each vertebra (except the sacral ones) forming the vertebral column region (cervical part, thoracic part, lumbar part) were determined for statistical analysis. We detected significant differences (P < 0.05) between sexes in all vertebrae forming the vertebral column of the chinchilla with respect to volume, surface area and vertebral body length, except for C6 and L1. This study is the first to carry out 3D reconstructions of data obtained from CT images in the chinchilla and the obtained results contribute to a more detailed understanding of the anatomy of this species. Our strategy may also be useful for the design of experiments exploring the vertebral column in domestic mammals and humans.

scholarly journals Bag of Geomorphological Words: A Framework for Integrating Terrain Features and Semantics to Support Landform Object Recognition from High-Resolution Digital Elevation Models

2020 ◽  
Vol 9 (11) ◽  
pp. 620
Author(s):  
Xiran Zhou ◽  
Xiao Xie ◽  
Yong Xue ◽  
Bing Xue ◽  
Kai Qin ◽  
...  
Keyword(s):  
Object Recognition ◽  
High Resolution ◽  
Feature Vector ◽  
Dimensional Space ◽  
Digital Elevation Models ◽  
Three Dimensional ◽  
Slope Aspect ◽  
Digital Elevation ◽  
Great Possibility ◽  
High Level

High-resolution digital elevation models (DEMs) and its derivatives (e.g., curvature, slope, aspect) offer a great possibility of representing the details of Earth’s surface in three-dimensional space. Previous research investigations concerning geomorphological variables and region-level features alone cannot precisely characterize the main structure of landforms. However, these geomorphological variables are not sufficient to represent a complex landform object’s whole structure from a high-resolution DEM. Moreover, the amount of the DEM dataset is limited, including the landform object. Considering the challenges above, this paper reports an integrated model called the bag of geomorphological words (BoGW), enabling automatic landform recognition via integrating point and linear geomorphological variables, region-based features (e.g., shape, texture), and high-level landform descriptions. First, BoGW semantically characterizes the composition of geomorphological variables and meaningful parcels of each type of landform. Based on a landform’s semantics, the proposed method then integrates geomorphological variables and region-level features (e.g., shape, texture) to create the feature vector for the landform. Finally, BoGW classifies a region derived from high-resolution DEM into a predefined type of landform by the feature vector. The experimental results on crater and cirque detection indicated that the proposed BoGW could support landform object recognition from high-resolution DEMs.

Using a Four-Dimensional Mesh Model to Represent a Tool Motion Trajectory in Five-Axis Machining

2014 ◽  
Vol 8 (3) ◽  
pp. 437-444 ◽  
Author(s):  
Hirotaka Kameyama ◽  
◽  
Ikuru Otomo ◽  
Masahiko Onosato ◽  
Fumiki Tanaka ◽  
...  
Keyword(s):  
Cutting Tools ◽  
Three Dimensional ◽  
3D Models ◽  
Temporal Changes ◽  
Cutting Process ◽  
Machining Processes ◽  
Mesh Model ◽  
Spatio Temporal ◽  
Five Axis ◽  
Mesh Models

In the field of machining processes, three-Dimensional (3D) models are commonly used to simulate the motions of cutting tools and workpieces. However, it is difficult for 3D models to represent spatio-temporal changes in their shapes continuously and to a high degree of accuracy. The objective of this study is to represent the 5-axis cutting process of workpiece transformation explicitly using a spatio-temporal model, the “four-Dimensional (4D) mesh model.” Every 4D mesh model is defined with bounding tetrahedral cells, and can continuously represent spatio-temporal changes of shape, position and orientation. In this study, the five-axis cutting process is described using accumulated volumes of 4D mesh models. Accumulated volumes are total volumes determined by spaces through which the object has passed. The use of accumulated volumes enables us to record tool-swept volumes and material removal shapes. First, this report introduces a 4D mesh model and the development of a 4D mesh modeling system. Next, a method of representing accumulated volumes as 4D mesh models is proposed. Generated 4D models are observed as 3D models by means of cross-section extraction.

scholarly journals Linking fishes to multiple metrics of coral reef structural complexity using three-dimensional technology

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
M. González-Rivero ◽  
A. R. Harborne ◽  
A. Herrera-Reveles ◽  
Y.-M. Bozec ◽  
A. Rogers ◽  
...  
Keyword(s):  
Coral Reef ◽  
Three Dimensional ◽  
Structural Complexity ◽  
Multiple Metrics

3D Mesh Model Coding

2011 ◽  
pp. 95-123
Author(s):  
Zhen Li
Keyword(s):  
3D Models ◽  
Future Research ◽  
Mesh Compression ◽  
Compression Algorithms ◽  
3D Mesh ◽  
Mesh Model ◽  
Data Representations ◽  
3D Mesh Model ◽  
Basic Concepts ◽  
Mesh Models

Application of 3D mesh model coding is first presented in this chapter. We then survey the typical existing algorithms in the area of compression of static and dynamic 3D meshes. In an introductory sub-section we introduce basic concepts of 3D mesh models, including data representations, model formats, data acquisitions and 3D display technologies. Furthermore, we introduce several typical 3D mesh formats and give an overview to coding principles of mesh compression algorithms in general, followed by describing the quantitative measures for 3D mesh compression. Then we describe some typical and state-of-the-art algorithms in 3D mesh compression. Compression and streaming of gigantic 3D models are specially introduced. At last, the MPEG4 3D mesh model coding standard is briefed. We conclude this chapter with a discussion providing an overall picture of developments in the mesh coding area and pointing out directions for future research.

scholarly journals Direct construction of a four-dimensional mesh model from a three-dimensional object with continuous rigid body movement

2014 ◽  
Vol 1 (2) ◽  
pp. 96-102 ◽  
Author(s):  
Ikuru Otomo ◽  
Masahiko Onosato ◽  
Fumiki Tanaka
Keyword(s):  
Rigid Body ◽  
Body Movement ◽  
Computing Time ◽  
Three Dimensional ◽  
3D Models ◽  
Direct Construction ◽  
3D Mesh ◽  
Mesh Model ◽  
3D Mesh Model ◽  
Dimensional Object

Abstract In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahe-dralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

Study on Geomorphologic Spatial Information Mining and Application

2011 ◽  
Vol 250-253 ◽  
pp. 1236-1242
Author(s):  
Li Heng Liang ◽  
Li Xin Xing ◽  
Tong Lin Li ◽  
Hong Yan Jiang ◽  
Li Jun Jiang
Keyword(s):  
Land Surface ◽  
Spatial Information ◽  
Digital Elevation Models ◽  
Three Dimensional ◽  
Shuttle Radar Topography Mission ◽  
Digital Elevation ◽  
Elevation Data ◽  
Local Relief ◽  
Local Window ◽  
Three Dimensional Coordinate

Digital Elevation Models (DEM) implies numbers of geomorphologic spatial information. It not only includes the three-dimensional coordinate but also has unique texture information, which can describe the ‘true’ land surface adequately at relation of neighbors (plan) and relative (amplitude). We will use a method to study the wavelength characters by data mining and distribution of slope and local relief on the altitude steps through a local window. The Shuttle Radar Topography Mission (SRTM) collect detailed Digital Elevation Models(DEM) data between 60°N and 57°S, 80 percent for all land masses, and it provides reliable, high precision surface elevation data for us, suits to analyze efficiently landscape pattern. SRTM-DEM data simulate three-dimensional land surface with regular gridded matrix, and these discrete points are fit for spatial neighbors’ analysis and statistics, and convenient to geomorphologic pattern computation and analysis in digital computer. Geomorphologic pattern is influenced by Physical properties and human activities in a most direct way, but whilst it record numbers of geological evolution evidence, and these records provide some important information for climate change, geological and geographical processes and ecological environment researches in science. In this study, making the whole Jilin province as study object, we propose a fourth-order equation to approximate land as a continuous curved surface, association neighbors’ analysis method, utilize digital elevation matrix to validate an optimal statistic window, and subsequent study the area spatial distribution by parameterization and classification, get a satisfactory effect.

scholarly journals MONITORING CORAL GROWTH – THE DICHOTOMY BETWEEN UNDERWATER PHOTOGRAMMETRY AND GEODETIC CONTROL NETWORK

2018 ◽  
Vol XLII-2 ◽  
pp. 759-766 ◽  
Author(s):  
F. Neyer ◽  
E. Nocerino ◽  
A. Gruen
Keyword(s):  
Coral Reef ◽  
Structural Complexity ◽  
Geodetic Network ◽  
3D Models ◽  
Control Network ◽  
3 Dimensional ◽  
Digital Ecosystem ◽  
Multi Temporal ◽  
Order Of Magnitude ◽  
Moorea Island

Creating 3-dimensional (3D) models of underwater scenes has become a common approach for monitoring coral reef changes and its structural complexity. Also in underwater archeology, 3D models are often created using underwater optical imagery. In this paper, we focus on the aspect of detecting small changes in the coral reef using a multi-temporal photogrammetric modelling approach, which requires a high quality control network. We show that the quality of a good geodetic network limits the direct change detection, i.e., without any further registration process. As the photogrammetric accuracy is expected to exceed the geodetic network accuracy by at least one order of magnitude, we suggest to do a fine registration based on a number of signalized points. This work is part of the Moorea Island Digital Ecosystem Avatar (IDEA) project that has been initiated in 2013 by a group of international researchers (https://mooreaidea.ethz.ch/).

scholarly journals Convolutional Neural Networks Predict Fish Abundance from Underlying Coral Reef Texture

2018 ◽  
Author(s):  
Grace Young ◽  
Vassileios Balntas ◽  
Victor Prisacariu
Keyword(s):  
Spatial Scales ◽  
A Priori ◽  
3D Structure ◽  
Three Dimensional ◽  
Structural Complexity ◽  
3D Models ◽  
Fish Abundance ◽  
Ecological Patterns ◽  
Abundance And Diversity ◽  
First Time

Coral reefs are among the most biodiverse ecosystems on Earth in large part owing to their unique three-dimensional (3D) structure, which provides niches for a variety of species. Metrics of structural complexity have been shown to correlate with the abundance and diversity of fish and other marine organisms, but they are imperfect representations of a surface that can oversimplify key structural elements and bias discoveries. Moreover, they require researchers to make relatively uninformed guesses about the features and spatial scales relevant to species of interest. This paper introduces a machine-learning method for automating inferences about fish abundance from reef 3D models. It demonstrates the capacity of a convolutional neural network (ConvNet) to learn ecological patterns that are extremely subtle, if not invisible, to the human eye. It is the first time in the literature that no a priori assumptions are made about the bathymetry–fish relationship.

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