Generic 3D Model Research Articles

FLATTENING COMPLEX ARCHITECTURAL SURFACES: PHOTOGRAMMETRIC 3D MODELS CONVERTED INTO 2D MAPS

Abstract. The paper describes a workflow to flatten 3D photogrammetric models of undevelopable surfaces into unfragmented 2D texture maps. The aim is to create a texture map with reduced fragmentation compared to typical photogrammetric texture files associated with 3D models. Geometric reformatting of the mesh is required to achieve an unfragmented final texture image with enough visual quality to allow for its use in 2D editing software (e.g., Photoshop, Illustrator, etc.). With a lighter model and defragmented texture, graphic documentation of conditions, treatments, or other relevant information can be performed directly. The approach considers both simple and complex architectural surfaces, with particular attention to elements that cannot be developed without introducing distortions. In the case of historic buildings, such surfaces constitute the majority, especially in the case of decorative elements and irregular vaulted systems. The approach extends to full 3D models, particularly those where orthomosaics would result in stretched details. We will discuss two methods: the first is particularly suitable when the photogrammetric project (oriented images) is still available, and the second applies to generic 3D models without the availability of the original images.

Reduction of additional pressure from ground construction on the subway escalator tunnel

The study considered options for reducing the additional pressure from the construction of a single-storey building on the underground structures of a deep shallow metro station. In the 3D formulation, the efficiency of the unloading «bridge» over the escalator tunnel was evaluated by the finite element method. It was found that the stiffer the grillage plate of the unloading «bridge», the more effectively the additional pressure from the building is transferred to the soils below the bottom of the escalator tunnel. However, in this case it is impossible to completely eliminate the additional pressure. In this regard, the option of creating an underground floor was considered. In this case, the weight of the selected from the excavation soil compensates the load from the building. The required depth of the basement floor was determined analytically, calculations were performed in characteristic sections on 2D models, and the operation of all structures in combination was considered on a general 3D model. Based on the results of the study, a rational algorithm was proposed for calculating the additional pressure from ground construction on underground subway structures.

Optimal seismic design of multiple-rocking steel concentrically-braced frames in 3D irregular buildings

This paper presents a gradient-based optimization approach for the seismic design of multiple-rocking systems in irregular buildings. The proposed design method tackles general 3D buildings with high torsional and vertical irregularities is developed. The design problem is formulated as an optimization problem that minimizes the construction cost of steel self-centering concentrically braced frames. The constraints are formulated based on current seismic design code requirements and recommendations from the literature. The structural response is computed using nonlinear time history analyses of general 3D models subjected to ensembles of ground accelerations.A dual-phase optimization approach is developed to reduce the computational effort and improve convergence In the first phase, a simplified numerical model is adopted for the analyses while the topology of the framing elements is not optimized. The second phase adopts a more detailed numerical model and starts with fixed location of the rocking sections. This enables topology optimization of the framing elements as well. The design method was implemented for the design of an 8-story building with two setbacks and high torsional irregularities subjected to an ensemble of ground accelerations, each having three components. The results show that this method provides efficient designs of these complex systems with a reasonable computational effort.

3D МОДЕЛЮВАННЯ ПРОЦЕСУ МАНЕВРУВАННЯ ЧОТИРИВІСНОГО КОЛІСНОГО ШАСІ З ДВОМА ПОВОРОТНИМИ ПЛАТФОРМАМИ

One of the ways to increase the maneuverability of the wheeled vehicles of the National Guard of Ukraine is to use a four-axle wheeled chassis with two turntables, which will allow the machine to turn with the smallest radius, move crab, sideways and turn around its own vertical axis. The creation of such a chassis is associated with a large amount of various experiments and tests of the finished sample. The development of computer technology and technologies has led to the creation of software applications for computer (simulation) modeling, which allow research and study of the properties of technical objects and systems under different conditions. The article developed a digital model of the chassis of a four-axle machine with two turntables and identified its features. For modeling, a powerful package of solid modeling Autodesk Inventor was chosen, which provides a comprehensive flexible set of tools for 3D design, visualization, instrumentation, analysis and calculations. When building a general 3D model of the chassis, the main features of the layout of parts and assemblies of this wheeled vehicle were taken into account. The forced rotation of the wheels and the rotation of the platforms were modeled by entering the value of a single parameter or setting using a graph. Depending on the needs of the experiment, graphs were set for displacements, speed or acceleration. In the course of a visual experiment, a simulation of the maneuvering of a four-axle vehicle was carried out for three options: turning the chassis to move in the opposite direction; changing the direction of movement through the turn of the chassis is a difficult maneuver; turning the chassis for sideways movement. The analysis of virtual studies showed that the control of the front, rear or both turntables is a promising way to increase the maneuverability of wheeled vehicles. In addition, the created computer prototype allows you to determine the main characteristics of the future product, carry out analysis, upgrade and necessary modification, set the desired trajectory of movement, including when passing through obstacles.

Modelling 3D force-free neutron star magnetospheres

ABSTRACT Magnetars exhibit a variety of transient high-energy phenomena in the form of bursts, outbursts, and giant flares. It is a common belief that these events originate in the sudden release of magnetic energy due to the rearrangement of a twisted magnetic field. We present global models of a 3D force-free (FF) non-linear twisted magnetar magnetosphere. We solve the FF equations following the Grad–Rubin approach in a compactified spherical domain. Appropriate boundary conditions are imposed at the surface of the star for the current distribution and the magnetic field. Our implementation is tested by reproducing various known analytical as well as axisymmetric numerical results. We then proceed to study general 3D models with non-axisymmetric current distributions, such as fields with localized twists that resemble hotspots at the surface of the star, and we examine characteristic quantities such as energy, helicity, and twist. Finally, we discuss implications on the available energy budget, the surface temperature, and the diffusion time-scale, which can be associated with observations.

The influence of the intermediate stress on the plane strain strength

A general 3D model is presented that includes the intermediate stress in strength analysis. The model is formulated in triaxial-compression strength parameters and the ratio between triaxial extension strength and triaxial compression strength. The model allows for a smooth transition between the expressions of Matsuoka-Nakai and Lade-Duncan. Starting from the general 3D model, the equivalent Mohr-Coulomb approach is developed for the commonly used calculation of failure loads for plane strain configurations. The approach includes the effect of the intermediate stress on the strength. The match between the general 3D model and the equivalent Mohr-Coulomb formulation is illustrated with Finite Element Method examples. Strain localisation is shown to be a dominant mechanism in the simulation of failure loads in the case of non-associativity. It is shown that Davis expressions derived from the equivalent Mohr-Coulomb model match the simulations of the general 3D model.

An Efficient Method to Determine the Thermal Behavior of Composite Material with Loading High Thermal Conductivity Fillers

Improvement of the thermal conductivity of encapsulant material using doping filler is an important requirement for electronic device packaging. We proposed a simple method for determining the thermal characteristics of composite material that can help save time, increase research performance, and reduce the cost of buying testing equipment. Based on the theory of Fourier law, a general 3D model is simplified into a 2D model, which can then be applied to calculate the thermal conductivity of the tested sample. The temperature distribution inside the sample is simulated by the finite element method using MATLAB software; this is a simple and useful option for researchers who conduct studies on thermal conduction. In addition, an experimental setup is proposed to help determine the extent of thermal conductivity improvement in a sample with doping filler compared to a bare sample. This method is helpful for research on optoelectronics packaging, which relates to the enhancement of thermal conductivity composite material.

Extension of the regularization technique to controlled-source electromagnetic modeling in general anisotropic conductivity media

Traditional Krylov subspace methods can be slow for electromagnetic modeling, particularly at lower frequencies. One of the commonly used remedies is to apply the divergence correction iteratively during the solution process, which requires solving an additional divergence correction equation. Alternatively, we have developed an efficient regularization technique to carry out the forward modeling of the anisotropic effect for 3D controlled-source electromagnetic data. Inside this scheme, we explicitly include the gradient of a scaled divergence correction term into the original curl-curl equation for general anisotropic conductivity structure. This inclusion leads to a significantly better-conditioned linear system of equations without changing the solution of the original system and avoids the solution of an additional equation. The correctness of the developed algorithm is examined based on a vertical transverse isotropic layered model with the semianalytical solution available. Then, we use a tilted transverse isotropic ocean canonical reservoir model and a general anisotropic 3D model to investigate the stability and efficiency of the algorithm. Numerical experiments demonstrate that the developed technique is 0.49–2.9 times faster than the standard algorithm at the considered frequencies.

Research of Ship Mission Profile Model

In view of the shipborne equipment carries out the need of mission under the condition of high and new technology, in order to clarify the relationship between the factors influencing the equipment operational effectiveness, depict the whole operational process in detail, established the general 3D model of ship mission profile. From time dimension, equipment dimension and criterion dimension, the mission process is fully described and has universality.

AREHS: effects of changing boundary conditions on the development of hydrogeological systems: numerical long-term modelling considering thermal–hydraulic–mechanical(–chemical) coupled effects

Abstract. Within the framework of the “Gesetz zur Suche und Auswahl eines Standortes für ein Endlager für hochradioaktive Abfälle” (Repository Site Selection Act – StandAG), the geoscientific and planning requirements and criteria for the site selection for a repository for high-active nuclear waste are specified. This includes, among others, the modelling of hydrogeological scenarios such as how future cold and warm periods and associated glaciation events can change the (petro-)physical properties specified in the StandAG as well as the natural hydrogeological properties of the overall system through, for example, reactivation of faults or changes in hydraulic gradients and consequently flow directions. The main objective of the AREHS (Effects of Changing Boundary Conditions on the Development of Hydrogeological Systems) project, funded by BASE (Federal Office for the Safety of Nuclear Waste Management; FKZ 4719F10402), is to model the effects of changing external boundary conditions on the hydrogeologically relevant parameters and effects (e.g. hydraulic permeability, porosity, migration pathways, fluid availability, hydraulic gradients) of a generic geological repository in Germany in all three potential host rocks (clay, salt and crystalline rocks) and its surrounding hydrogeological setting (Table 1). Special attention is paid to the cyclic mechanical loading and unloading due to glaciation events and the resulting stress changes (M), as well as induced temperature effects (T) due to permafrost and warm periods. As such processes can cause changes in the coupled far-field regime with groundwater flow and groundwater supply (H), as well as fluid transport due to thermal (T) and chemical (C) gradients, and reactivate faults/fractures (M) and thus create new/additional pathways, they are particularly relevant to the integrity of a repository over a period of 1 million years and must be properly captured with coupled THM(C) modelling. Before a model is set up for the different host rocks, a detailed assessment of relevant processes has been conducted based on NEA-2019 FEP catalogue (NEA, 2019) for high-level waste repositories. The modelling is performed using generic 3D models of typical host rock formations satisfying the StandAG criteria. Although the models for salt and clay rock have been adapted from generic models from recent research projects, for crystalline rock a new generic model had to be developed (Fig. 1) considering discontinuities of different scales that have to be incorporated into the THM(C) models explicitly as DFN (Discrete Fracture Network) networks. This is done by coupling two numerical codes: DFN-lab and 3DEC. A central phase in the overall modelling process is the benchmarking of the models with data from existing models and with field-scale studies. This is done separately for all three host rocks. In addition to extending the modelling capacities for glaciation processes and verifying by corresponding benchmarking tests (analytical solutions and literature comparisons), automated workflows have been developed to generate OpenGeoSys models from GOCAD structure models. Script-based automated workflows improve software quality for site investigation, especially in a sense of modularization as well as reproducibility. The generic workflow concept is currently being tested for the literature-based benchmarks and will, therefore, support a persistent and sustainable benchmarking procedure in the future.

Tidal evolution of the Pluto–Charon binary

A giant collision is believed to be at the origin of the Pluto–Charon system. As a result, the initial orbit and spins after impact may have substantially differed from those observed today. More precisely, the distance at periapse may have been shorter, subsequently expanding to its current separation by tides raised simultaneously on the two bodies. Here we provide a general 3D model to study the tidal evolution of a binary composed of two triaxial bodies orbiting a central star. We apply this model to the Pluto–Charon binary, and notice some interesting constraints on the initial system. We observe that when the eccentricity evolves to high values, the presence of the Sun prevents Charon from escaping because of Lidov-Kozai cycles. However, for a high initial obliquity for Pluto or a spin-orbit capture of Charon’s rotation, the binary eccentricity is damped very efficiently. As a result, the system can maintain a moderate eccentricity throughout its evolution, even for strong tidal dissipation on Pluto.

A General 3D Model for Growth Dynamics of Sensory-Growth Systems: From Plants to Robotics.

In recent years, there has been a rise in interest in the development of self-growing robotics inspired by the moving-by-growing paradigm of plants. In particular, climbing plants capitalize on their slender structures to successfully negotiate unstructured environments while employing a combination of two classes of growth-driven movements: tropic responses, growing toward or away from an external stimulus, and inherent nastic movements, such as periodic circumnutations, which promote exploration. In order to emulate these complex growth dynamics in a 3D environment, a general and rigorous mathematical framework is required. Here, we develop a general 3D model for rod-like organs adopting the Frenet-Serret frame, providing a useful framework from the standpoint of robotics control. Differential growth drives the dynamics of the organ, governed by both internal and external cues while neglecting elastic responses. We describe the numerical method required to implement this model and perform numerical simulations of a number of key scenarios, showcasing the applicability of our model. In the case of responses to external stimuli, we consider a distant stimulus (such as sunlight and gravity), a point stimulus (a point light source), and a line stimulus that emulates twining of a climbing plant around a support. We also simulate circumnutations, the response to an internal oscillatory cue, associated with search processes. Lastly, we also demonstrate the superposition of the response to an external stimulus and circumnutations. In addition, we consider a simple example illustrating the possible use of an optimal control approach in order to recover tropic dynamics in a way that may be relevant for robotics use. In all, the model presented here is general and robust, paving the way for a deeper understanding of plant response dynamics and also for novel control systems for newly developed self-growing robots.

Stiffness modeling of a variable stiffness compliant link

Recently, a variable stiffness robotic link based on the rotating beam concept has been developed for applications in physical human robot interaction. A substantial challenge for design of such links is the modeling of stiffness behavior to permit stiffness control. In this paper we present a general 3D model of the link stiffness using screw theory and compliance matrices as well as a planar model for the lateral and torsional stiffness. Since axial buckling is a major failure mode, we also derive an analytical model for predicting axial buckling behavior. The analytical models are compared to the finite element method and experimental results. One of the challenges involved in design and analysis of variable stiffness links is the parasitic compliance of the mechanical elements that support and drive the active portion of the mechanism. For the design analyzed in this paper, we use the models we derive to identify the major sources of parasitic compliance and suggest optimizations to minimize their effects. These results can be used as guidelines for designing variable stiffness links.

The haloes and environments of nearby galaxies (HERON) – II. The outer structure of edge-on galaxies

ABSTRACT The haloes and environments of nearby galaxies (HERON) project is aimed at studying haloes and low surface brightness (LSB) details near galaxies. In this second HERON paper, we consider in detail deep imaging (down to surface brightness of ∼28 mag arcsec−2 in the r band) for 35 galaxies, viewed edge-on. We confirm a range of LSB features previously described in the literature but also report new ones. We classify the observed outer shapes of the galaxies into three main types (and their prototypes): disc/diamond-like (NGC 891), oval (NGC 4302), and boxy (NGC 3628). We show that the shape of the outer disc in galaxies does not often follow the general 3D model of an exponential disc: 17 galaxies in our sample exhibit oval or even boxy isophotes at the periphery. Also, we show that the less flattened the outer disc, the more oval or boxy its structure. Many galaxies in our sample have an asymmetric outer structure. We propose that the observed diversity of the galaxy outer shapes is defined by the merger history and its intensity: if no recent multiple minor or single major merging took place, the outer shape is diamond-like or discy. On the contrary, interacting galaxies show oval outer shapes, whereas recent merging appears to transform the outer shape to boxy.

BDSIM: An accelerator tracking code with particle–matter interactions

Beam Delivery Simulation (BDSIM) is a program that simulates the passage of particles in a particle accelerator. It uses a suite of standard high energy physics codes (Geant4, ROOT and CLHEP) to create a computational model of a particle accelerator that combines accurate accelerator tracking routines with all of the physics processes of particles in Geant4. This unique combination permits radiation and detector background simulations in accelerators where both accurate tracking of all particles is required over long range or over many revolutions of a circular machine, as well as interaction with the material of the accelerator. Program summaryProgram Title: BDSIMProgram Files doi:http://dx.doi.org/10.17632/bzg5hc65h6.1Licensing provisions: GNU General Public License 3Programming language: C++, flex, bisonExternal routines/libraries: Geant4, CLHEP, ROOT, gzstream, CMakeNature of problem: Simulate energy deposition and charged particle detector background in a particle accelerator originating from beam loss where particles may pass both through the vacuum pipe with magnetic and electromagnetic fields, as well as through the material of the magnets and accelerator itself. Simulate the passage of particles both through an accelerator and the surrounding material such as air. Do so in a sufficiently flexible way that a variety of accelerator configurations can be easily simulated.Solution method: Automatic creation of a 3D Geant4 model from an optical description of an accelerator using a library of generic 3D models that are user extendable. Accelerator tracking routines, the associated fields and coordinates transforms are provided for accurate magnetic field tracking.

Maintaining Semantic Information across Generic 3D Model Editing Operations

Many of today’s data models for 3D applications, such as City Geography Markup Language (CityGML) or Industry Foundation Classes (IFC) encode rich semantic information in addition to the traditional geometry and materials representation. However, 3D editing techniques fall short of maintaining the semantic information across edit operations if they are not tailored to a specific data model. While semantic information is often lost during edit operations, geometry, UV mappings, and materials are usually maintained. This article presents a data model synchronization method that preserves semantic information across editing operation relying only on geometry, UV mappings, and materials. This enables easy integration of existing and future 3D editing techniques with rich data models. The method links the original data model to the edited geometry using point set registration, recovering the existing information based on spatial and UV search methods, and automatically labels the newly created geometry. An implementation of a Level of Detail 3 (LoD3) building editor for the Virtual Singapore project, based on interactive push-pull and procedural generation of façades, verified the method with 30 common editing tasks. The implementation synchronized changes in the 3D geometry with a CityGML data model and was applied to more than 100 test buildings.

A Surface Division Method of Parts Mesh Model for On-Machine Inspection

As a general 3D model data format, triangular mesh model has been widely used in mechanical engineering to realize the function of transmitting data between different CAD software, but during the transmission, a large amount of geometric and topological data from mechanical parts has been lost. In order to solve this problem while using triangular mesh model in On-Machine Inspection (OMI), in this paper, a surface division method of parts mesh model for OMI is proposed, intending to solve the problem about mesh model that divided into triangular pieces cannot be operated during OMI. The proposed method contains two processes: boundary line extraction and mesh model division. During the process of extracting boundary line of model surface, a method of extracting coordinate points on the model boundary is proposed by analyzing the Gauss curvature between triangular surfaces, and then using the maximum entropy threshold theory to analyze the correlation between coordinate points to screen out the qualified model boundary line. In the process of mesh model division, based on the extracted model boundary, a mesh segmentation method based on region - growing algorithm is studied to obtain the triangular mesh within the boundary. At last, the validity of the descripted method is verified by some example.

Effect of Axial Profile Modification on the Characteristics of a Finite Length Misaligned Journal Bearing

Misalignment in journal bearings is a common industrial problem which affects the general performance of the bearing. This includes a significant effect on the load carrying capacity of the bearing and the change in the level and shape of the pressure distribution. There are many causes for the presence of misalignment in the practical uses of the journal bearing system, such as deflection of the shaft under high levels of load, manufacturing errors, installation error, and others. In the case of severe misalignment levels, a sharp drop in the lubricant film thickness or even a direct contact may occur between the shaft and the bearing at the edges of the bearing. This paper considers such extreme cases of misalignment, where the introduction of bearing axial profile modification to prevent edge contacts is investigated in detail. A general 3D model of misalignment for the case of a finite length bearing is considered in the analyses, where the Reynolds equation is solved numerically based on the finite difference method. The results reveal that the use of profile modification leads to an improvement in the levels of film thickness and an increase in the load-carrying capacity of the bearing.

An automated 3D modeling pipeline for constructing 3D models of MONOGENEAN HARDPART using machine learning techniques

BackgroundStudying structural and functional morphology of small organisms such as monogenean, is difficult due to the lack of visualization in three dimensions. One possible way to resolve this visualization issue is to create digital 3D models which may aid researchers in studying morphology and function of the monogenean. However, the development of 3D models is a tedious procedure as one will have to repeat an entire complicated modelling process for every new target 3D shape using a comprehensive 3D modelling software. This study was designed to develop an alternative 3D modelling approach to build 3D models of monogenean anchors, which can be used to understand these morphological structures in three dimensions. This alternative 3D modelling approach is aimed to avoid repeating the tedious modelling procedure for every single target 3D model from scratch.ResultAn automated 3D modeling pipeline empowered by an Artificial Neural Network (ANN) was developed. This automated 3D modelling pipeline enables automated deformation of a generic 3D model of monogenean anchor into another target 3D anchor. The 3D modelling pipeline empowered by ANN has managed to automate the generation of the 8 target 3D models (representing 8 species: Dactylogyrus primaries, Pellucidhaptor merus, Dactylogyrus falcatus, Dactylogyrus vastator, Dactylogyrus pterocleidus, Dactylogyrus falciunguis, Chauhanellus auriculatum and Chauhanellus caelatus) of monogenean anchor from the respective 2D illustrations input without repeating the tedious modelling procedure.ConclusionsDespite some constraints and limitation, the automated 3D modelling pipeline developed in this study has demonstrated a working idea of application of machine learning approach in a 3D modelling work. This study has not only developed an automated 3D modelling pipeline but also has demonstrated a cross-disciplinary research design that integrates machine learning into a specific domain of study such as 3D modelling of the biological structures.

3-D Face Alignment Using A Convolutional Point-Set Representation

We present a robust method for estimating the facial pose and shape parameters with a Projected Normalized Coordinate Code (PNCC), a derived image where each pixel is annotated with its corresponding vertex position in a generic 3D model. The method relies on a Convolutional Point-set Representation (CPR), a carefully designed feature map that extracts useful information encoded in pairs or triplets of vertices of PNCC. To estimate the shape and pose parameters, different CPRs are designed to represent mutually independent pose and shape parameters. The CPRs are then fed into multiple convolutional networks (with recurrent layers) in a sequential manner based on the transformation order of weak-perspective projection model to predict the target parameters. Reprojection errors are sampled along a predicted direction and the parameters are updated based on the pattern of reprojection errors. This technique boosts the model’s capability to find a local minimum under challenging scenarios. It is also demonstrated that CPRs obtained from different sources can be merged and contribute to outperforming the current state-of-the-art solutions for 3D face alignment. Experiments indicate that the proposed CPRFA (CPR-based Face Alignment) significantly improves 3D alignment accuracy. Compared to 3DDFA, the proposed method reduces the normalized mean error on AFLW2000 and AFLW database by 25.3% and 20.2% respectively.