A new algorithm for finding faces in wireframes

Varley, Peter

doi:10.1016/j.cad.2009.11.008

Cited by 29 publications

(39 citation statements)

References 27 publications

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“…To reduce the search complexity, methods in this class only identify cycles with a limited variety of geometry, such as planar cycles [Markowsky and Wesley 1980;Liu et al 2002;Varley and Company 2010] or cycles bounding low-degree algebraic surfaces [Sakurai and Gossard 1983]. While cycles in CAD wireframe mostly fall into these types, curve sketches usually have more geometric variation (see Figure 10).…”

Section: Planar Graph Embeddingmentioning

confidence: 99%

A general and efficient method for finding cycles in 3D curve networks

et al. 2013

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Figure 1: A curve network (misc2) representing a genus-7 mechanical part (left), cycles found by our algorithm (middle), and surface patches generated from the cycles (right). The curve network contains 410 curves. Our algorithm completed in half a second. AbstractGenerating surfaces from 3D curve networks has been a longstanding problem in computer graphics. Recent attention to this area has resurfaced as a result of new sketch based modeling systems. In this work we present a new algorithm for finding cycles that bound surface patches. Unlike prior art in this area, the output of our technique is unrestricted, generating both manifold and nonmanifold geometry with arbitrary genus. The novel insight behind our method is to formulate our problem as finding local mappings at the vertices and curves of our network, where each mapping describes how incident curves are grouped into cycles. This approach lends us the efficiency necessary to present our system in an interactive design modeler, whereby the user can adjust patch constraints and change the manifold properties of curves while the system automatically re-optimizes the solution.

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Section: Planar Graph Embeddingmentioning

confidence: 99%

A general and efficient method for finding cycles in 3D curve networks

et al. 2013

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“…These papers provide polynomial-time algorithms by guaranteeing that not too many cycles are examined. Along with Varley [VC10], we observe that weighting cycles by total edge length does not seem to lead to good results in patch finding. Our main innovation is the observation that weighting cycles, rather than edges, allows us to encode a much more flexible variety of heuristics into the set of weights, and that any choice of cycle weights can be easily optimized via the greedy algorithm.…”

Section: Related Workmentioning

confidence: 89%

Surface Patches from Unorganized Space Curves

Abbasinejad

Joshi

Amenta

2011

Computer Graphics Forum

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Figure 1: Our system takes as input a wireframe model produced from a 3D curve sketch, and outputs a set of curved surface patches representing the object. The output objects need not be manifold, or connected. From left to right, phoenix, roadster, spider and boat curve networks created with ILoveSketch on top, and the output sets of surface patches on the bottom. AbstractRecent 3D sketch tools produce networks of three-space curves that suggest the contours of shapes. The shapes may be non-manifold, closed three-dimensional, open two-dimensional, or mixed. We describe a system that automatically generates intuitively appealing piecewise-smooth surfaces from such a curve network, and an intelligent user interface for modifying the automatically chosen surface patches. Both the automatic and the semi-automatic parts of the system use a linear algebra representation of the set of surface patches to track the topology. On complicated inputs from ILoveSketch [BBS08], our system allows the user to build the desired surface with just a few mouse-clicks.

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“…Although further improvements are still required, conversion from wireframe sketches into 2D linedrawings is a well known stage in SBM (readers should look for "recognition" in [16]), but conversion from natural into wireframe line-drawings is not so easy [15], [17]. Faces must also have been detected in advance (the process of finding faces in 2D B-Reps of polyhedral objects has been explained elsewhere [18]). Hence, we assume a graph-like wireframe input containing a list of vertices, a list of edges and a list of faces.…”

Section: Finding Ribs and Dividers In Single-view Wireframesmentioning

confidence: 99%

Perceiving Ribs in Single-View Wireframe Sketches of Polyhedral Shapes

Varley

Plumed

Martin

2012

Advances in Visual Computing

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Abstract. As part of a strategy for creating 3D models of engineering objects from sketched input, we attempt to identify design features, geometrical structures within objects with a functional meaning. Our input is a 2D B-Rep derived from a single view sketch of a polyhedral shape. In this paper, we show how to use suitable cues to identify algorithmically two additive engineering design features, angular and linear ribs. IntroductionOur aim is to find design features, geometrical structures within objects with a functional meaning. In a previous paper [1], we presented a catalogue of common design features, listing for each type of feature any known successful algorithms for detecting the implied presence of such features in sketches. We noted that, as a result of previous interest in machining features, there are many known algorithms for detecting subtractive features or "intrusions", but far fewer algorithms for detecting additive features or "protrusions" [2,3]. Our motivation in this paper is to fill this gap.We briefly review what is known about both human and artificial perception of features, and we then introduce a new approach aimed at finding one specific design feature, the rib, through indirect cues. We distinguish between angular ribs (or simply ribs) and linear ribs (or rails). The new contribution here is the search for perceptual cues linked to features embedded in the sketched shapes.Because of their function, ribs are theoretically important in computer-aided design as the ideal size of a rib for a particular size of part depends on strength calculations. Once a feature has been flagged as a rib, a CAD/CAE package should know that its dimensions are to be fixed not by geometric constraints but by the physical properties of the material. It is thus important to find and classify ribs to distinguish them from more "geometric" features.Our intended approach differs from other feature recognition performed on inaccurate models in that our input is a 2D graph-like line-drawing, derived from a single view sketch of a polyhedral shape. This introduces one intrinsic limitation: as sketches contain only pictorial information, depth information comes only from the interpretation of perceptual cues. The second limitation, considering only polyhedral shapes, is a simplification that we hope we will relax in the future.

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A new algorithm for finding faces in wireframes

Cited by 29 publications

References 27 publications

A general and efficient method for finding cycles in 3D curve networks

A general and efficient method for finding cycles in 3D curve networks

Surface Patches from Unorganized Space Curves

Perceiving Ribs in Single-View Wireframe Sketches of Polyhedral Shapes

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