Conceptual Design of a 3D Visualization Platform for Ships Based on Digital Twin Technology

Addressing the challenges in the current ship’s lifecycle design process, such as high difficulty in information sharing and complex installation of design environments, this study proposes a concept design of a ship 3D visualization platform based on digital twin technology. It constructs a web-based ship 3D visualization platform with an interactive interface of realism. The aim is to avoid cumbersome client-side programs and provide a method to showcase and interact with ship 3D models on web pages. This method not only reduces the threshold for ordinary users but also significantly enhances the work efficiency of professional designers. Following the model construction theory of digital twin platforms, it utilizes WebGL technology and the Three.js library to build ship 3D scenes, achieving ship 3D visualization. Functional interaction among modules is implemented using JavaScript, establishing the digital twin of the ship. Test results indicate that the proposed concept design of the ship 3D visualization platform can preliminarily fulfill the basic requirements of achieving ship 3D display, rendering, and interaction on web platforms. The proposed method can support the development of ship online collaborative design systems based on front-end internet technologies.


Introduction
The shipping industry is pivotal for global trade and national development.IT tools for ship design and operations are gaining traction due to increased resource demand.Recent research highlights 3D visualization technology's potential in ship analysis and maintenance.Scholars like Ham S.H [1] focus on simulation frameworks for ship motion analysis, while Ueng [2] and Liu [3] explore detailed visualizations and maintenance models using technologies like VR and browser-server architecture.These studies offer insights for shipping's visualization research.Yet, addressing challenges in maritime development, digital twin technology gains attention.Bekker A [4] delves into sensor-based digital twin ship models, while [5] uses data-driven methods to reduce fuel consumption due to hull fouling.To support maritime enterprises, a lightweight cloud-based platform using twin technology is crucial.This platform enables real-time ship model display on web pages.Hence, this paper proposes a ship 3D visualization platform based on digital twin technology using WebGL and Three.js,enabling real-time interaction and virtual-physical integration.

Digital Twin-based Ship 3D Visualization Platform Design
To facilitate interaction between the information space and physical realm in fields such as ship design, manufacturing, and long-distance navigation, we've integrated cutting-edge information technology with conventional manufacturing techniques to establish a lightweight platform for visualizing ship design.This effective visualization method enables a clear representation of real-life scenarios in a virtual environment, allowing comprehensive monitoring and management of ship design, manufacturing, and related processes.This paper presents a conceptual design platform for 3D visualization of ships based on digital twin technology, following the concept of the five-dimensional model [6] of data twins.The overall conceptual model is illustrated in Figure 1.

Figure 1. Digital Twin Conceptual Model of Ships
In this platform, the physical entity corresponds to the ship entity, existing in the real world; the virtual model corresponds to the ship model, synchronously mapped from the physical ship entity into the virtual world; ship 3D visualization application represents the application of digital twin technology in ship design, allowing the display and interaction with the digital twin ship model; twin data refers to real-time generated ship data, serving as a means of interconnection across various applications.

Application of Digital Twin-based Ship 3D Visualization Platform
Hydrostatics play a crucial role in ship performance calculations, holding significant importance for tasks like optimizing ship designs and verifying floating conditions.To address the complexities and computational intensity observed in current mainstream ship hydrostatic calculation methods, this paper proposes a rapid, simplified, and lightweight approach leveraging the characteristics of internet frontend technology.This approach utilizes a straightforward method: it starts by importing ship models in STL format, which are then rasterized to create encrypted coordinate matrices representing the ship's hull values.Numerical integration is carried out along the ship's length and draft, computing sectional area curves and waterline area curves.These computations yield the ship's displacement volume, subsequently showcasing all calculated results on a web page for user access.In contrast to traditional ship hydrostatic calculations, this method significantly reduces computational costs.Additionally, it leverages web technology to circumvent intensive client-side computations and data transmissions, achieving the goal of a streamlined design.Figure 2 illustrates the technical roadmap for ship hydrostatic calculation.

Figure 2. Diagram of Static Hydrodynamic Calculation Technique
"Grid generation" refers to the process of projecting a three-dimensional object onto a two-dimensional plane, followed by dividing the two-dimensional plane into a structured grid.Each grid unit represents the properties of the corresponding space, stored in a regular matrix form for subsequent calculations.An STL model consists of numerous irregular triangular facets with irregularly positioned vertices, making it unsuitable for hydrostatic calculations.To address this, the irregular STL 3D model is partitioned into a structured rectangular grid matrix.This grid matrix is then used for interpolation calculations based on hydrostatic calculation formulas, ultimately resulting in the determination of the ship model's displacement volume.Figure 3   Through the aforementioned computation process, once the ship's hydrostatics calculation is completed, the findings will be showcased on the web page.This article establishes a hidden module that can conceal the computed ship displacement volume, waterline area curve, and cross-sectional area curve, making the interface more organized.Upon clicking the display button, the results of the hydrostatic calculation will be revealed for users' convenience in viewing.

Conclusion
This article proposes a concept design for a 3D visualization platform for ships based on digital twin technology.It applies digital twin technology to the ship design phase, utilizing WebGL technology and Three.js to build virtual scenes.This platform achieves the mapping between physical and virtual spaces, allowing comprehensive display and interaction with ship structures in a virtual environment.Additionally, it rapidly calculates the ship's displacement volume and visually presents the waterline area curves, simplifying the process of hydrostatics calculation.The digital twin-based 3D visualization platform resolves issues such as low information sharing efficiency throughout the ship's lifecycle.It aids designers in escaping cumbersome client-side operations, enhancing ship design efficiency.Furthermore, it provides a research direction for visualizing digital twin ships, demonstrating the applicability of digital twins in ship design phases.

References
[1] Ham S H, Roh M I, Zhao L.
displays a three-dimensional surface view of the ship model.

Figure 4 .
Figure 4. Waterline Area Curve Calculation Interface Integrated Method of Analysis, Visualization, and Hardware For Ship Motion Simulation J 2018.Journal of Computational Design and Engineering [2] Ueng, Shyh-Kuang, Lin, et al.A Ship Motion Simulation System J 2008.Virtual Reality.[3] Liu Jinghao, Su Qian, Chen Junjie, et al.Research on Railway Maintenance Visualization Based on WebGL Extended Model J 2022.Journal of Railway Science and Engineering, 19(04): 892-900.[4] Bekker A. Exploring The Blue Skies Potential Of Digital Twin Technology for a Polar Supply and Research Vessel C 2018.Proceedings of the 13th International Marine Design Conference.[5] Coraddu A, Oneto L, Baldi F, et al.Data-driven Ship Digital Twin for Estimating The Speed Loss Caused By The Marine Fouling J 2019.Ocean Engineering.[6] Tao Fei, Liu Weiran, Zhang Meng, et al.Five-Dimensional Digital Twin Model and Its Top Ten Domain Applications J 2019.Journal of Computer Integrated Manufacturing Systems, 25(01): 1-18.