• Deciphering the Influence of Product Shape on Consumer Judgments Through Geometric Abstraction


    Understanding and tailoring the visual elements of a developing product to evoke desired perceived qualities and a positive response from the consumer is a key challenge in industrial design. To date, computational approaches to assist this process have either relied on stiff geometric representations, or focused on superficial features that exclude often elusive shape characteristics. In this work, we aim to study the relationship between product geometry and consumers’ qualitative judgments through a visual decomposition and abstraction of existing products. At the heart of our investigation is a shape analysis method that produces a spectrum of abstractions for a given three-dimensional (3D) computer model. Our approach produces a hierarchical simplification of an end product, whereby consumer response to geometric elements can be statistically studied across different products, as well as across the different abstractions of one particular product. The results of our case study show that consumer judgments formed by coarse product “impressions” are strongly correlated with those evoked by the final production models. This outcome highlights the importance of early geometric explorations and assessments before committing to detailed design efforts.

  • Pencil-like Sketch Rendering of 3D Scenes Using Trajectory Planning and Dynamic Tracking


    Objective: We present a new non-photorealistic rendering method to render 3D scenes in the form of pencil-like sketches.

    Methods: This work is based on the observation that the dynamic feedback mechanism involving the human visual system and the motor control of the hand collectively generates the visual characteristics unique to hand-drawn sketches. At the heart of our approach is a trajectory planning and tracking algorithm that generate the sketch in multiple layers using a dynamic pen model. On each layer, a set of target strokes are generated from the silhouette lines, edges, and shaded regions which serve as the target trajectory for a closed-loop dynamic pen model. The pen model then produces the rendered sketch, whose characteristics can be adjusted with a set of trajectory and tracking parameters. This process continues in several layers until the tonal difference between the sketch and the original 3D render is minimized.

    Results: We demonstrate our approach with examples that are created by controlling the parameters of our sketch rendering algorithms.

    Conclusion: The examples not only show typical sketching artifacts that are common to human-drawn sketches but also demonstrate that it is capable of producing multiple sketching styles.

  • Sketch-Based Aesthetic Product Form Exploration from Existing Images Using Piecewise Clothoid Curves


    We present a new sketch-based product form exploration technique that works from images and sketches of existing products. At the heart of our approach, is a multi-stroke curve beautification method and a curve-based image deformation algorithm. The proposed approach converts groups of strokes into piecewise clothoid curves in order to produce visually pleasing shapes. The deformation diffusion algorithm then spatially distributes the user specified deformations through out the image to produce smooth transformations from the original image to the resulting image. We demonstrate the technique on a variety of images including photo-realistic images, real product images, and sketches.

  • Shape Design From Exemplar Sketches Using Graph-Based Sketch Analysis


    We describe a new technique that works from a set of concept sketches to support the exploration and engineering of products. Our approach allows the capture and reuse of geometric shape information contained in concept sketches, as a means to generate solutions that can concurrently satisfy aesthetic and functional requirements. At the heart of our approach is a graph-based representation of sketches that allows the determination of topological and geometric similarities in the input sketches. This analysis, when combined with a geometric deformation analysis, results in a design space from which new shapes can be synthesized, or a developing design can be optimized to satisfy prescribed objectives. Moreover, it facilitates a sketch-based, interactive editing of existing designs that preserves the shape characteristics captured in the design space. A key advantage of the proposed method is that shape features common to all sketches as well as those unique to each sketch can be separately identified, thus allowing a mixing of different sketches to generate a topologically and geometrically rich set of conceptual alternatives. We demonstrate our technique with 2D and 3D examples.

  • Sketch-Based Surface Design Using Malleable Curve Networks


    We present a new 3D surface modeling approach that enables curve-based creation and modification of smooth surfaces by sketching. The key feature of the proposed methods is a two-way communication between the user-designed curve networks and the generated surfaces. A user-drawn curve network serves as a control cage, from which a subdivision surface is generated. The subdivision surface is updated to match the curve network while minimizing the curvature variation throughout the surface. Surface fairness is controlled independently to modify the curve network into suitable configurations that guarantee a smooth underlying surface. This approach enables a concurrent modeling of the curve network and the underlying surface, thus eliminating the need for a laborious, iterative adjustment of the curve network for smooth surface creation. We demonstrate our approach with example models, and evaluate it with a user study.

  • Sketch-based shape exploration using multiscale free-form surface editing


    The hierarchical construction of solid models with current computer-aided design systems provides little support in creating and editing free-form surfaces commonly encountered in industrial design. In this work, we propose a new design exploration method that enables sketch-based editing of free-form surface geometries where specific modifications can be applied at different levels of detail. This multilevel detail approach allows the designer to work from existing models and make alterations at coarse and fine representations of the geometry, thereby providing increased conceptual flexibility during modeling. At the heart of our approach lies a multiscale representation of the geometry obtained through a spectral analysis on the discrete free-form surface. This representation is accompanied by a sketch-based surface editing algorithm that enables edits to be made at different levels. The seamless transfer of modifications across different levels of detail facilitates a fluid exploration of the geometry by eliminating the need for a manual specification of the shape hierarchy. We demonstrate our method with several design examples.

  • Beautification of Design Sketches Using Trainable Stroke Clustering and Curve Fitting


    We propose a new sketch parsing and beautification method that converts digitally created design sketches into beautified line drawings. Our system uses a trainable, sequential bottom-up and top-down stroke clustering method that learns how to parse input pen strokes into groups of strokes each representing a single curve, followed by point-cloud ordering that facilitates curve fitting and smoothing. This approach enables greater conceptual freedom during visual ideation activities by allowing designers to develop their sketches using multiple, casually drawn strokes without requiring them to indicate the separation between different stroke groups. With the proposed method, raw sketches are seamlessly converted into vectorized geometric models, thus, facilitating downstream assessment and editing activities.

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