Soonjo Kwon

Simplification of feature-based 3D CAD assembly data of ship and offshore equipment using quantitative evaluation metrics

In the design process for ship outfitting and offshore plants, an equipment catalog database is compiled in order for shipyards to reutilize data effectively. However, the current procedure for building such a catalog causes wastage of time because the modelers in the shipyard must perform manual modeling of the 3D CAD data in order to decrease the size of 3D CAD data and adopt a different level of detail (LOD) depending on the purpose of its use. This problem arises because equipment suppliers are not willing to give all of their 3D CAD data to shipyards, out of fear of the loss of intellectual property. Moreover, the 3D CAD data of equipment suppliers have a high LOD, while a shipyards 3D CAD data have a relatively low LOD. Therefore, it is necessary to introduce an automated method to simplify the 3D CAD assembly data for equipment that is received from the equipment supplier. In addressing this problem, this study first proposes criteria for a simplification process and quantitative evaluation metrics for the simplification of 3D CAD assembly data, considering the characteristics of equipment data in the shipbuilding industry. Based on these findings, a simplification system was developed, and, four experimental test cases that were conducted on-site were used to verify the proposed system. The results showed that the data to be stored could be reduced to at least 25% of the original 3D CAD assembly data while ports, outer boundaries, and connectivity between CAD parts could be maintained. Display Omitted Shipyards need simplified equipment 3D CAD assembly data for system-level design.Three simplification operations applicable for 3D CAD assembly data are developed.Evaluation metrics considering multiple simplification criteria are proposed.The evaluation metrics allow discriminatory priority of specific criteria.

Graph-Based Simplification of Feature-Based Three-Dimensional Computer-Aided Design Models for Preserving Connectivity

The required level of detail (LOD) of a three-dimensional computer-aided design (3D CAD) model differs according to its purpose. It is therefore important that users are able to simplify a highly complex 3D CAD model and create a low-complexity one. The simplification of a 3D CAD model requires the application of a simplification operation and evaluation metrics for the geometric elements of the 3D CAD model. The evaluation metrics are used to select those elements that should be removed. The simplification operation removes selected elements in order to simplify the 3D CAD model. In this paper, we propose the graph-based simplification of feature-based 3D CAD models using a method that preserves connectivity. First, new evaluation metrics that consider the discrimination priority among several simplification criteria are proposed. Second, a graph-based refined simplification operation that prevents the separation of a feature-based 3D CAD model into multiple volumes is proposed. Finally, we verify the proposed method by implementing a prototype system and performing simplification experiments using feature-based 3D CAD models.

Enhancement of equipment information sharing using three-dimensional computer-aided design simplification and digital catalog techniques in the plant industry

Process plants are designed and constructed by engineering, procurement, and construction companies, which order various types of equipment to be installed in them. Equipment manufacturers design and produce the ordered equipment, and deliver it to the customer. Therefore, equipment information sharing between them is an important issue for engineering collaboration in a plant project. However, they use different three-dimensional computer-aided design systems for different purposes. For this reason, additional three-dimensional computer-aided design and data merging techniques are required for equipment information sharing. This article presents a new approach to share equipment information using three-dimensional computer-aided design simplification and digital catalog techniques. In this approach, the equipment’s three-dimensional computer-aided design data generated by a manufacturer are first simplified and then converted into neutral three-dimensional computer-aided design. The converted three-dimensional computer-aided design data are merged with port and specification data into a digital catalog. Equipment information in the form of this digital catalog is finally delivered to the engineering, procurement, and construction companies.

Determination of appropriate level of detail of a three-dimensional computer-aided design model from a permissible dissimilarity for fully automated simplification:

The level of detail required for a three-dimensional computer-aided design model varies according to its purpose. Thus, it is necessary to develop an automated method for controlling the level of detail of three-dimensional computer-aided design models to facilitate the use of three-dimensional computer-aided design models in different application areas. When multiple three-dimensional computer-aided design models need to be simplified in a batch mode without user intervention, it would be advantageous if the appropriate level of details for the models were automatically determined. This study proposes a new and automated method to determine the appropriate level of detail of each three-dimensional computer-aided design model during the simplification phase. To achieve this goal, the concept of an “appropriate level of detail for simplification” was defined from the viewpoint of shape dissimilarity. After that, an algorithm was developed to determine the appropriate level of detail of a model by adopting the feature-based simplification method and the shape distribution–based comparison method. Finally, a prototype system was invented to verify the proposed method through experiments, in which the appropriate level of details for test cases were determined by the system.

Development of 3D CAD Part Data Simplification System for Ship and Offshore Plant Equipment

It is necessary to construct equipment catalog in ship outfitting design and offshore plant design. The three-dimensional CAD data of equipment take on different level-of-detail depending on the purpose. Equipment suppliers provide CAD data with high complexity while ship designers need CAD data with low complexity. Therefore, it is necessary to simplify CAD data. However, it takes much time to simplify them manually. To resolve the issue, a system for automatically simplifying the 3D CAD data of equipment was developed. This paper presents the architecture of the system and the implementation details. In addition, experiment result using the prototype system is explained.

A web-based solution for collaborative design supporting multiple CAD systems

Collaborative engineering design is a time-consuming process because the collaborative partners are spatially distant and familiar with divergent software solutions due to their local circumstances. The data compatibility problem rises between collaborating groups because each group uses a particular software solution that is different from other groups. A platform independent web-based solution for collaborative CAD system, that supports files of multiple CAD systems as well, has been implemented in this paper. The implemented solution saves time by providing web-based editing and visualization and preserves the design intent that makes it reusable.

User-assisted integrated method for controlling level of detail of large-scale B-rep assembly models

ABSTRACT In recent times, there is a growing demand for technologies that control the level of detail (LOD) of large-scale three-dimensional (3D) computer-aided design (CAD) models. In particular, in industrial plants and in the construction industry, there is a significant need for simplification of large-scale models, because the number of models to be dealt with is tremendously large and their complexity is high. The degree of automation is, however, very low in these industries. As a result, many additional costs arise in the process of manually regenerating the 3D CAD models by the users. To resolve this problem, this study suggests a way to control effectively the LOD of large-scale B-rep assembly models. The proposed method consists of filtering, to remove those parts that ought to be removed, and progressive control, to remove sequentially the features acquired by volume decomposition. The user intervenes in the progressive control stage and adjusts the LOD for each component of the assembly. Based on the proposed method, a prototype system was implemented and experiments were performed for two test cases. The data size of the two test cases decreased, in average, to 65% in the first stage and 85% in the second stage. It was also found that the proposed component-level LOD control method is suitable and practical for a large-scale model.