Cheng-Hung Lo

One-Step QFD based 3D morphological charts for concept generation of product variant design

This paper proposes a novel methodology, QFD based 3D morphological charts, to support variant design of simple and technically mature products. Customers requirements are incorporated in developing the morphological charts through a holistic approach, One-Step QFD. In contrast to the traditional cascading deployment, members from marketing, design, and manufacturing teams concurrently derive the requirements from three different aspects. The charts driven by the deployment results produce design concepts of high feasibility through query by function, specification, and module of a product. They are presented in 3D assembly for better visual stimuli rather than clutter of 2D sketches. A computer-aided conceptual design system is implemented to realize the proposed ideas with computer mice as an example product. A design experiment is conducted to compare the quantity and quality of the concepts generated with and without the aid of the system. The results show that it promotes quick generation of innovative concepts while maintaining their manufacturability.

Shape similarity measurement for 3D mechanical part using D2 shape distribution and negative feature decomposition

This paper proposes a novel measurement scheme of 3D shape similarity that integrates D2 Shape Descriptor and Negative Feature Decomposition (NFD). Using NFD, the scheme firstly converts a 3D mechanical part into a tree structure of geometrical primitives decomposed from the part model, namely Negative Feature Tree (NFT). The D2 shape descriptions of these primitives are then produced for further similarity assessments. We assess the shape similarity on a level-by-level basis between the NFTs of a query part and a candidate part. The weighted sum of the similarity values computed on each level is then used as a measure of the overall similarity between the two parts. Our approach combines the simplicity of D2 shape description while overcoming its insensitivity to negative features with NFD. It performs more consistently than the method of Convex Hull Difference (CHD). A comparison with the assessment results using D2 and CHD demonstrates the effectiveness of the new scheme.

Affective Modelling: Profiling Geometrical Models with Human Emotional Responses

In this paper, a novel concept, Affective Modelling, is introduced to encapsulate the idea of creating 3D models based on the emotional responses that they may invoke. Research on perceptually‐related issues in Computer Graphics focuses mostly on the rendering aspect. Low‐level perceptual criteria taken from established Psychology theories or identified by purposefully‐designed experiments are utilised to reduce rendering effort or derive quality evaluation schemes. For modelling, similar ideas have been applied to optimise the level of geometrical details. High‐level cognitive responses such as emotions/feelings are less addressed in graphics literatures. This paper investigates the possibility of incorporating emotional/affective factors for 3D model creations. Using a glasses frame model as our test case, we demonstrate a methodological framework to build the links between human emotional responses and geometrical features. We design and carry out a factorial experiment to systematically analyse how certain shape factors individually and interactively influence the viewers impression of the shape of glasses frames. The findings serve as a basis for establishing computational models that facilitate emotionally‐guided 3D modelling.

Selective rendering for efficient ray traced stereoscopic images

Depth-related visual effects are a key feature of many virtual environments. In stereo-based systems, the depth effect can be produced by delivering frames of disparate image pairs, while in monocular environments, the viewer has to extract this depth information from a single image by examining details such as perspective and shadows. This paper investigates via a number of psychophysical experiments, whether we can reduce computational effort and still achieve perceptually high-quality rendering for stereo imagery. We examined selectively rendering the image pairs by exploiting the fusing capability and depth perception underlying human stereo vision. In ray-tracing-based global illumination systems, a higher image resolution introduces more computation to the rendering process since many more rays need to be traced. We first investigated whether we could utilise the human binocular fusing ability and significantly reduce the resolution of one of the image pairs and yet retain a high perceptual quality under stereo viewing condition. Secondly, we evaluated subjects’ performance on a specific visual task that required accurate depth perception. We found that subjects required far fewer rendered depth cues in the stereo viewing environment to perform the task well. Avoiding rendering these detailed cues saved significant computational time. In fact it was possible to achieve a better task performance in the stereo viewing condition at a combined rendering time for the image pairs less than that required for the single monocular image. The outcome of this study suggests that we can produce more efficient stereo images for depth-related visual tasks by selective rendering and exploiting inherent features of human stereo vision.

A novel course paradigm for teaching collaborative product development in distributed environments

Collaborative product development (CPD) has recently become one of the important business strategies for the companies to remain competent in the Greater China region. Geographically separate companies such as design studios and manufacturers are required to participate in the product development process in a dispersed manner. Traditional product design courses may not be able to equip students with working knowledge in this regard. To overcome this deficiency, we have developed a novel course paradigm that combines two modular courses: manufacturing engineering (ME) and new product development (NPD). The students from the two courses are grouped into individual teams, and each team is required to complete a product development project within one semester. In each team, the ME students act as the engineering staff while the NPD students take the roles of marketing people and project managers. However, the ME and NPD students are required to collaborate remotely over the Internet. Face-to-face communication is deemed as being unavailable so as to mimic the real CPD scenarios. The tasks and materials involved in this new course include team building, project management, budget control, outsourcing, product design, prototyping, and ICT tools, e.g. teleconferencing, CAD, and PDM. The feedbacks from the graduated students working in industry validate the education goals in the course design.

Cognitive shape similarity assessment for 3D part search

Mass customization aims to satisfy diverse customer requirements with high product variety while maintaining reasonable manufacturing cost and lead time. Allowing customers to perceive product differentiation is a critical factor for most design methods developed for mass customization. This study examines 3D part search from the human cognitive perspective. We designed and conducted a quasi-factorial experiment to understand how structured variations of four factors—the shape, type, dimension, and location of the feature volume of a part model—affect human judgment of part similarity. The corresponding factorial similarity values were computed with different shape signatures in the form of the feature adjacency graph. The human responses were obtained by paired comparisons of test parts, and quantified as the cognitive similarity. Statistical analysis of the experimental results showed that the type and shape factors played an important role in the subjects’ judgments. Back-propagation neural networks were trained to model the correlations between the cognitive and the factorial similarity values. The performance of the networks validates our idea of incorporating human cognition into assessment of 3D part similarity. This study presents a systematic approach for personalized part search that reflects individual perception of shape similarity.

An efficient procedure for locating joint centers on 3D scanned human models: using hip joint centers as an example

This paper presents an efficient procedure to locate joint centers on 3D scanned human models. Using the hip joint centers (HJCs) as an example, we conducted an experiment to study the validity of the procedure. We carried out 3D body scanning on six subjects, which were attached with the necessary body landmarks. Another 12 participants were recruited to perform two tasks. The first task was to identify the locations of the body landmarks. We pre-programmed the estimation method to an in-house rigging system. The lower body bones were then placed by the system according to the estimated HJCs. The second task was to place the lower body bones based on visual judgments. The results show that the HJCs obtained in the first task are more accurate. The results are also visually demonstrated. The promising results of the experiment indicate the possibility of building skeletal structures with 3D body scanning.

Does the Design Style Influence the Perception of Product Performance Charts

Product performance charts are commonly seen in the product reviews published on the relevant web sites, magazines, and other public media. They are aimed at helping consumers understand the similarities and differences among the gathered products. This study investigates whether the design style influences the perception of the product performance charts. And this paper presents the result of an initial experiment that evaluates three chart types, including bar charts, count charts, and radar charts. The result shows that the participants may evaluate a product differently if presented with different design style. The result of this initial experiment provides some interesting insights. Further investigations that follow will include the dimensional factors and the more in-depth analysis of how a consumer responds to product performance charts.

Evaluating the Effect of Interactions Between Appearance-Related Product Designs and Facial Characteristics on Social Affectivity

For products that can improve the appearance of the user, such as facial accessories, both the characteristics of the product user and design features must be considered in design evaluation. This paper proposes an experimental evaluation scheme that investigates the interactions between the design features of 3D eyeglasses frames and user facial characteristics. Face models of users containing both geometric and image data were constructed using 3D scanning. A face deformation method was developed to manipulate individual facial features without changing the other features on the face models. In the evaluation scheme, participants judged synthetic faces, which had varied eye distances and orientations and were wearing factorized eyeglasses frames, according to three affective measures related to the personality attributes of confidence, friendliness, and attractiveness. The experimental results show that changing certain design features influences the impressions of the face models with varied facial characteristics. The proposed scheme facilitates designing products that strengthen the impression of specific personality traits by accommodating individual differences in facial features.Copyright

Evaluating Interactions between Appearance-Related Product Designs and Facial Characteristics

Design prototype evaluation plays a crucial role in user experience assessment. This paper proposes an evaluation scheme to investigate interactions between design features of a product and user facial characteristics. Glasses frames design is used as an example to illustrate how the scheme works. 3D scanning technology is applied to capture the facial features of users and reconstruct their 3D face models. Those models allow us to post-process individual facial feature without changing the others. Subjects respond to three affective measures: confidence, friendliness, and attractiveness, signified by the faces wearing the factorized glasses frames. The results show that changing certain design features indeed influences the impressions of the faces with varied facial characteristics. The proposed scheme facilitates design of products related to personal appearance.