Component‐wise Controllers for Structure‐Preserving Shape Manipulation

Abstract

Recent shape editing techniques, especially for man-made models, have gradually shifted focus from maintaining local, low-level geometric features to preserving structural, high-level characteristics like symmetry and parallelism. Such new editing goals typically require a pre-processing shape analysis step to enable subsequent shape editing. Observing that most editing of shapes involves manipulating their constituent components, we introduce component-wise controllers that are adapted to the component characteristics inferred from shape analysis. The controllers capture the natural degrees of freedom of individual components and thus provide an intuitive user interface for editing. A typical model usually results in a moderate number of controllers, allowing easy establishment of semantic relations among them by automatic shape analysis supplemented with user interaction. We propose a component-wise propagation algorithm to automatically preserve the established inter-relations while maintaining the defining characteristics of individual controllers and respecting the user-specified modeling constraints. We extend these ideas to a hierarchical setup, allowing the user to adjust the tool complexity with respect to the desired modeling complexity. We demonstrate the effectiveness of our technique on a wide range of manmade models with structural features, often containing multiple connected pieces.

Recovering Functional Mechanical Assemblies from Raw Scans

“…Our work also shares resemblance to the large body of methods on structure-based shape analysis and modeling [17], [18], [19], [20], [21], [22], [23], wherein high-level shape structures are identified with low-dimensional parts of different sizes, positions, and interactions. Gal et al [17] demonstrated that working with a set of 1D feature curves extracted from engineered objects, and preserving their intra-and inter-relations while deforming the shapes lead to an intuitive manipulation framework.…”

Ergonomics-Inspired Reshaping and Exploration of Collections of Models

“…Shape deformation is a longstanding topic in geometry processing [20]. The shape deformation methods mainly fall into two classes: those that aim to preserve the shape's local properties, such as curvature, differential coordinates [21], [22], [23], and those that aim to preserve global structures, such as symmetry and inter-part relations [24], [25], [26]. Li et al [27] deform input man-made objects to make them amenable to stacking.…”

“…Each node in the graph corresponds to a component, while each edge denotes a contact or symmetry relation (see Figure 4). We fit each component with a primitive (in our system cuboid and cylinder, computed via PCA); we call such a primitive a proxy, which is later used to guide the deformation of the underlying component [26]. We compute the contact information between adjacent components by considering their point-to-point distances.…”

“…Shape deformation methods, either implicit or explicit, aim to optimize a given shape to fulfill the edit constraints while preserving the shape's intrinsic properties, or more importantly, the structure. Recently, advanced techniques have been exploited [25], [26], which either use identifying shape features (e.g., feature curves) or high-level deformation delegators (e.g., controllers) to induce the underlying structural optimization, which typically involves complicated strategies to transfer the edits progressively or hierarchically. These methods often proceed one edit at a time, thus it is not clear whether their methods could handle cases when multiple edit constraints are in dependence.…”

Illustrating the disassembly of 3D models

“…Recently, understanding the higher-level representations of 3D models has received considerable interest (see survey [11]), including symmetry detection [12,13,14], upright orientation inference [15] and shape abstractions [16]. Benefitting from these techniques, a wide spectrum of applications are spawned, such as shape manipulation [17,18,19], shape synthesis [20], motion analysis [21,22,23,24] and computational furniture design [25]. In addition, many works focus on the analysis of individual parts within an input model, which are similar to our framework.…”