Modeling Of Trees Research Articles

Real Time Modeling and Rendering of 3D Tree

In recent years, the virtual-reality simulation technology has developed so fast which has been widely used in military and people’s daily lives, etc. As the essential element of the three-dimensional scene, modeling of trees becomes increasingly important. There are many methods for 3D modeling trees such as 3DMAX modeling, the bulletin board technology, the crossing panel and the LOD technology. However, these methods are not so effective either for the bad real-time performance caused by the large quantity of data or the unsatisfactory 3D effect. Therefore, this paper is aiming at proposing a 3D tree modeling method which was based on the combination of Fractal and Non-rectangular raster image technology.

Automatic Modeling of Fault Tree for NuIEEE Transactions on Power Electronics,Clear Power Safety I&C Configuration

The automatic modeling of fault tree for nuclear power safety I&C configuration is designed to meet the requirements of reducing the workload and improving the traceability during the nuclear power safety I&C system reliability assessment work. To complete the fault tree automatic modeling, the Visio Automation software technology is used to analyze the topology of the nuclear power safety I&C system hardware device and software function. The good result in practical implementations shows that the nuclear power safety I&C system fault tree modeling work is successfully simplified.

Individualization of Decision Making Regarding Mammographic Screening for Breast Cancer in Women 40-49 y.o. with First Degree Relative with Breast Cancer

This paper aims to help health care providers to advise the healthy female patients age of 40-49 y.o. who have one first degree relative with breast cancer, whether she should or should not participate in mammographic screening. The author’s patient is anxious whether she should have her mammogram done and whether it will benefit her. Her sister was most recently diagnosed with breast fibroadenoma. In order to answer their patient’s question the author take into consideration medical aspects of mammography as a screening test, and integrate them with patient values and preferences into a single decision-making model. This paper is based on the modeling of a decision tree, using the information extracted from open sources and peer-reviewed publications. It is based on comprehensive search for each model parameter, but is not an all-inclusive systematic review. The purpose of this work is both educational and practical: the authors try to apply the decision analysis methodology in an attempt to solve this dilemma while trying to avoid or at least minimize biased assumptions regarding usefulness of mammography in this group of patients. Based on their proposed model the decision regarding the participation into mammographic screening in this particular scenario is highly driven by patient values and preferences.

Design of vascular networks: A mathematical model approach

In this paper, methods for the modeling of a realistic vascular tree in 3D space and for hemodynamic calculating throughout the simulated tree structure have been developed. Vascular trees are generated based on the power law relationship. Variations in branching asymmetry and segment length of the vasculature are precisely controlled by the designed gaussian distributions. The resolution limit of current imaging techniques for vessel detectability is simulated by designed pruning technique. On the basis of the generated diameters and lengths, the space locations of the vessel segments are calculated by optimizing the out-of-plane angles of two daughter branches. The generated vascular tree not only follows the power law relationship, but also maximizes the filling volume of the tree structure in 3D space. From the hemodynamic calculation in the simulated vasculature, the processes for which structural changes affect hemodynamic distributions are studied in detail. And also, the fractal nature and resistance of the vascular trees are quantified and compared. The developed method provides some insight into the design of the vascular trees in biology and may be used as a reference for the study of vascular diseases.

New Algorithm for Modeling of Bronchial Trees

Abstract The article presents new conception of 3D model of human bronchial tubes, which represents bronchial tubes extracted from CT images of the chest. The new algorithm which generates new model is an extension of the algorithm (basic algorithm) proposed by Hiroko Kitaoka, Ryuji Takaki and Bela Suki. The basic model has been extended by geometric deformations of branches and noise which occur in bronchial trees extracted from CT images. The article presents comparison of results obtained with the use of the new algorithm and the basic one. Moreover, the discussion of usefulness of generated new models for testing of algorithms for quantitative analysis of bronchial tubes based on CT images is also included.

Compositional Generative Mapping for Tree-Structured Data—Part I: Bottom-Up Probabilistic Modeling of Trees

We introduce a novel compositional (recursive) probabilistic model for trees that defines an approximated bottom-up generative process from the leaves to the root of a tree. The proposed model defines contextual state transitions from the joint configuration of the children to the parent nodes. We argue that the bottom-up context postulates different probabilistic assumptions with respect to a top-down approach, leading to different representational capabilities. We discuss classes of applications that are best suited to a bottom-up approach. In particular, the bottom-up context is shown to better correlate and model the co-occurrence of substructures among the child subtrees of internal nodes. A mixed memory approximation is introduced to factorize the joint children-to-parent state transition matrix as a mixture of pairwise transitions. The proposed approach is the first practical bottom-up generative model for tree-structured data that maintains the same computational class of its top-down counterpart. Comparative experimental analyses exploiting synthetic and real-world datasets show that the proposed model can deal with deep structures better than a top-down generative model. The model is also shown to better capture structural information from real-world data comprising trees with a large out-degree. The proposed bottom-up model can be used as a fundamental building block for the development of other new powerful models.

Easy modeling of realistic trees from freehand sketches

Creating realistic 3D tree models in a convenient way is a challenge in game design and movie making due to diversification and occlusion of tree structures. Current sketch-based and image-based approaches for fast tree modeling have limitations in effect and speed, and they generally include complex parameter adjustment, which brings difficulties to novices. In this paper, we present a simple method for quickly generating various 3D tree models from freehand sketches without parameter adjustment. On two input images, the user draws strokes representing the main branches and crown silhouettes of a tree. The system automatically produces a 3D tree at high speed. First, two 2D skeletons are built from strokes, and a 3D tree structure resembling the input sketches is built by branch retrieval from the 2D skeletons. Small branches are generated within the sketched 2D crown silhouettes based on self-similarity and angle restriction. This system is demonstrated on a variety of examples. It maintains the main features of a tree: the main branch structure and crown shape, and can be used as a convenient tool for tree simulation and design.

Efficient modeling of numerous trees by introducing growth volume for real‐time virtual ecosystems

ABSTRACTThis study suggests a growth volume system for the efficient modeling of numerous trees for a real‐time virtual ecosystem. To increase the efficiency of the real‐time system and to allow natural tree generation, the basic tree modeling system obtains its growth rule by means of botany‐based self‐organizing under a recursive hierarchy structure. On the basis of this rule, growth volume was introduced and controlled to generate numerous trees in a virtual ecosystem more intuitively, which allows the generation of various trees. The reality of the expression was increased by including the effects of external factors, such as light, physical obstacles, and other trees. Finally, an instancing‐based branch control procedure was added to enable an efficient rendering of the real‐time ecosystem. Experiments were performed to verify whether various and natural trees could be generated and numerous trees in the virtual ecosystem can be easily modeled on the basis of the suggested growth volume, which shows the efficiency of the real‐time ecosystem. Copyright © 2012 John Wiley & Sons, Ltd.

Stochastic modelling of tree annual shoot dynamics

• Context Modelling annual shoot development processes is a key step towards functional–structural modelling of trees. Various patterns of meristem activity can be distinguished in tree shoots, with active periods of phytomer production followed by rest periods. This approach has seldom been integrated in functional–structural tree models.

Logical models for the propagation of disparate information and uncertainty across effectivity trees

An effectivity tree is a new concept which we introduce to show how it can be used in applications related to uncertainty quantification of the widely varying information that typical plagues many complex problems. Modeling of effectivity trees can b

Tree modelling from mobile laser scanning data‐sets

AbstractIn recent times mobile laser scanning (MLS) has been used to acquire massive 3D point clouds in urban areas and along road corridors for the collection of detailed data for 3D city modelling, building façade reconstruction and capture of vegetation and road features for inventories. The objectives of this paper are the extraction of tree features from such data‐sets and the modelling of trees for the purpose of visualisation in 3D city models. After the detection of high vegetation the point cloud is reduced using a 3D alpha shape approach. Then the required model parameters such as crown and stem height, crown and stem diameter, and crown shape are derived and the trees are modelled individually in a realistic manner. The tree model so generated correctly represents the overall appearance of the tree. However, the inner structure such as the branching of the tree crown is parameterised. The workflow reduces the point cloud by means of a step‐by‐step process, which eases the handling of the massive MLS data‐sets. The thinning using 3D alpha shapes reduces the amount of data to be processed by about 95%. It is shown that the model parameters are not influenced by the thinning procedure employed. This proves the robustness of the data reduction method and the tree modelling approach.

Spatial modeling of habitat trees based on line transect sampling and point pattern reconstruction

An approach is presented for the spatial modeling of rare habitat trees surveyed by line transect sampling (LTS) in a protected area of the European Natura 2000 network. The observed tree pattern is defined as a realization of a thinned point process where the thinning can be modeled by a parametric detection function. A complete pattern is reconstructed using an optimization algorithm. The start configuration contains detected tree locations and randomly generated tree positions. Empirical cumulative distribution functions (ECDFs) for intertree and location-to-tree distances estimated from the original LTS are set as target characteristics. The same ECDFs are estimated by means of virtual LTS in the reconstruction. Tree positions are relocated during the optimization. The sum of squared deviations between the ECDFs from the original LTS and the virtual LTS in the reconstruction is considered as a contrast measure. A new configuration is accepted if the contrast is lowered compared with the previous state. The nonparametrically reconstructed habitat tree patterns are described by a log Gaussian Cox process model. Evaluations by means of line transect resamplings in a complete habitat pattern show small deviations between the second-order functional characteristics obtained from the true pattern and their analogs derived from the reconstructions.

Structural design of a natural windbreak using computational and experimental modeling

Computational and experimental approaches are employed for the structural design of a natural windbreak. It is intended to find the optimum tree shelterbelt to obviate the uneven wind speed distribution across the width dimension of a high-level competition rowing channel. The experimental results, obtained in a wind tunnel, and consisting of erosion-technique images and local wind-speed measurements, are used to benchmark the computational model. A good agreement between the two sets of results is obtained. Several windbreak configurations, considering one or two rows of different cross-sectional shape and porosity, are computationally modeled. For the shortest row a rectangular shape, with porosity of 35%, is considered; for the tallest row, which aims the modeling of a poplar tree, a porosity of 87% is assumed at the trunk level, and 60% at the crown. The optimum shelterbelt consists of two rows, composed by bamboo and poplar trees, which allows the attainment of a low and nearly uniform wind flow across the width of the channel.

戸建住宅の室温および熱負荷に対する樹木の影響

The heat load simulation program which can take into consideration the shadow effects caused by trees is developed by the authors.And, the effects on the indoor environments by the trees which cover the afternoon sun was verified.The program added the function in which transmissivity can be set up to the external obstacle. Moreover, the form of the external obstacle was updated so that all polygons could be taken into consideration. Modeling of trees was enabled by those updating.By using a deciduous tree, reducing cooling load, the increase in heating load could be suppressed and annual heating-and-cooling loads were reduced about 3.6%.

A 2-adic approach of the human respiratory tree

We propose here a general framework to address the question of trace operators on a dyadic tree. This work is motivated by the modeling of the human bronchial tree which, thanks to its regularity, can be extrapolated in a natural way to an infinite resistive tree. The space of pressure fields at bifurcation nodes of this infinite tree can be endowed with a Sobolev space structure, with a semi-norm which measures the instantaneous rate of dissipated energy. We aim at describing the behaviour of finite energy pressure fields near the end.The core of the present approach is an identification ofthe set of ends with the ring $\ZZ$2 of 2-adic integers. Sobolev spaces over $\ZZ$2 can be defined in a very natural way by means of Fourier transform, which allows us to establish precised trace theorems which are formally quite similar to those in standard Sobolev spaces, with a Sobolev regularity which depends on the growth rate of resistances, i.e. on geometrical properties of the tree. Furthermore, we exhibit an explicit expression of the 'ventilation operator'', which maps pressure fields at the end of the tree onto fluxes, in the form of a convolution by a Riesz kernel based on the 2-adic distance.

Cajals achievements in the field of the development of dendritic arbors

In 1909, Cajal published an up-dated version in French (Cajal, 1909-1911) of his main work Texture of the Nervous System of Man and Vertebrates (Cajal, 1899-1904), considered the most important book devoted to the nervous system. Owing that last year was the centenary of this publication, we decided to produce an article focused on Cajals description of the morphological changes that dendritic trees undergo during development. We will emphasize his brilliant hypotheses explaining the modelling of dendritic trees (the neurotropic hypothesis and the role of neuronal activity in the patterning of the dendritic trees), and the status of this topic in present day Neuroscience. Here, we will show original photographs taken from a selected collection of Cajals slides housed in the Cajal Museum (Instituto Cajal, CSIC, Madrid, Spain) illustrating the principal changes in neuronal morphology at different stages of development of the spinal cord, cerebellum and cerebral cortex. We will also discuss Cajals initial proposals regarding the influence of neurotropic substances (chemotactic hypothesis) and neural activity in the modelling of the dendritic tree, as well as the evidence that later confirmed these theories.

Interactive Modeling of 3D Tree with Ball B-Spline Curves

A novel approach to modeling realistic tree easily through interactive methods based on ball B-Spline Curves (BBSCs) and an efficient graph based data structure of tree model is proposed in the paper. As BBSCs are flexible for modifying, deforming and editing, these methods provide intuitive interaction and more freedom for users to model trees. If conjuncted with other methods like generating tree models through L-systems or iterated function systems (IFS), the models are more realistic and natural through modifying and editing. The method can be applied to the design of bonsai tree models.

Image-Based Modeling of Plants and Trees

Image-Based Modeling of Plants and Trees

Aerodynamic modelling of trees for small-scale wind tunnel studies

Summary In building and environmental aerodynamics, wind tunnel studies of natural vegetative structures like bushes or trees have to be modelled. From a fl uid mechanical point of view, these structures differ essentially from man-made constructions because of their structural fl exibility and permeability. Whereas the small-scale modelling of technical structures is widely known, a lack of knowledge exists in an adequate modelling of vegetative structures. In this article, aerodynamic characteristics of infl exible model trees with crowns of varying porosity are presented. Drag force and fl ow fi eld measurements were performed in a uniform or boundary layer fl ow, respectively. The force measurements delivered drag coeffi cients in the range of 0.8 – 1.2. This is in good accordance with natural trees for low wind velocities (<10 m s 1 ). Flow fi eld measurements show typical wake characteristics of permeable structures with recirculation zones being extended or even detached when compared with impermeable bodies. By means of spectral analysis, an energy shift from lower to higher frequencies, i.e. a breakdown of larger eddy structures into smaller eddies, in the crown wake region was found.

A Lidar Point Cloud Based Procedure for Vertical Canopy Structure Analysis And 3D Single Tree Modelling in Forest.

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 the original Lidar raw point cloud. The main tree canopy layers and the height ranges of the layers are detected according to a statistical analysis of the height distribution probability of the normalized raw points. For the 3D modelling of individual trees, individual trees are detected and delineated not only from the top canopy layer but also from the sub canopy layer. The normalized points are resampled into a local voxel space. A series of horizontal 2D projection images at the different height levels are then generated respect to the voxel space. Tree crown regions are detected from the projection images. Individual trees are then extracted by means of a pre-order forest traversal process through all the tree crown regions at the different height levels. Finally, 3D tree crown models of the extracted individual trees are reconstructed. With further analyses on the 3D models of individual tree crowns, important parameters such as crown height range, crown volume and crown contours at the different height levels can be derived.