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18
Recognitionbycomponents: A theory of human image understanding
 Psychological Review
, 1987
"... The perceptual recognition of objects is conceptualized to be a process in which the image of the input is segmented at regions of deep concavity into an arrangement of simple geometric components, such as blocks, cylinders, wedges, and cones. The fundamental assumption of the proposed theory, recog ..."
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Cited by 742 (11 self)
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The perceptual recognition of objects is conceptualized to be a process in which the image of the input is segmented at regions of deep concavity into an arrangement of simple geometric components, such as blocks, cylinders, wedges, and cones. The fundamental assumption of the proposed theory, recognitionbycomponents (RBC), is that a modest set of generalizedcone components, called geons (N ^ 36), can be derived from contrasts of five readily detectable properties of edges in a twodimensional image: curvature, collinearity, symmetry, parallelism, and cotermmation. The detection of these properties is generally invariant over viewing position and image quality and consequently allows robust object perception when the image is projected from a novel viewpoint or is degraded. RBC thus provides a principled account of the heretofore undecided relation between the classic principles of perceptual organization and pattern recognition: The constraints toward regularization (Pragnanz) characterize not the complete object but the object's components. Representational power derives from an allowance of free combinations of the geons. A Principle of Componential Recovery can account for the major phenomena of object recognition: If an arrangement of two or three geons can be recovered from the input, objects can be quickly recognized even when they are occluded, novel, rotated in depth, or extensively degraded. The results from experiments on the perception of briefly presented pictures by human observers provide empirical support for the theory. Any single object can project an infinity of image configurations to the retina. The orientation of the object to the viewer can vary continuously, each giving rise to a different twodimensional projection. The object can be occluded by other objects or texture fields, as when viewed behind foliage. The object need not be presented as a fullcolored textured image but instead can be a simplified line drawing. Moreover, the object can even be missing some of its parts or be a novel exemplar of its
Creating solid models from single 2D sketches
, 1995
"... We describe a method of constructing a Brep solid model from a single hiddenline removed sketch view of a 3D object. The main steps of our approach are as follows. The sketch is first tidied in 2D (to remove digitisation errors). Line labelling is used to deduce the initial topology of the object ..."
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Cited by 19 (4 self)
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We describe a method of constructing a Brep solid model from a single hiddenline removed sketch view of a 3D object. The main steps of our approach are as follows. The sketch is first tidied in 2D (to remove digitisation errors). Line labelling is used to deduce the initial topology of the object and to locate hidden faces. Constraints are then produced from the line labelling and features in the drawing (such as probable symmetry) involving the unknown face coefficients and point depths. A least squares solution is found to the linear system and any grossly incompatible equations are rejected. Vertices are recalculated as the intersections of the faces to ensure we have a reconstructible solid. Any incomplete faces are then completed as far as possible from neighbouring faces, producing a solid model from the initial sketch, if successful. The current software works for polyhedral objects with trihedral vertices.
Automatic Creation of BoundaryRepresentation Models from Single Line Drawings
, 2002
"... This thesis presents methods for the automatic creation of boundaryrepresentation models of polyhedral objects from single line drawings depicting the objects. This topic is important in that automated interpretation of freehand sketches would remove a bottleneck in current engineering design metho ..."
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Cited by 17 (11 self)
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This thesis presents methods for the automatic creation of boundaryrepresentation models of polyhedral objects from single line drawings depicting the objects. This topic is important in that automated interpretation of freehand sketches would remove a bottleneck in current engineering design methods. The thesis does not consider conversion of freehand sketches to line drawings or methods which require manual intervention or multiple drawings. Thge thesis contains a number of...
EmpiricallyDerived Estimates of the Complexity of Labeling Line Drawings of Polyhedral Scenes
 Artificial Intelligence
, 1998
"... Several results have been obtained in the past about the complexity of understanding line drawings of polyhedral scenes. Kirousis and Papadimitriou (1988) have shown that the problem of labeling line drawings of trihedral scenes is NPcomplete. The human brain, however, seems to grasp at a glance th ..."
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Cited by 12 (1 self)
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Several results have been obtained in the past about the complexity of understanding line drawings of polyhedral scenes. Kirousis and Papadimitriou (1988) have shown that the problem of labeling line drawings of trihedral scenes is NPcomplete. The human brain, however, seems to grasp at a glance the 3D structure associated with a line drawing. A possible explanation of this discrepancy, offered by Kirousis and Papadimitriou themselves, is that the worstcase complexity does not reflect the real difficulty of labeling line drawings, which might be far less in the average or in "typical" cases. However, no statistical analysis has ever been carried out to test this conjecture. The core of this paper is an algorithm for the generation of random instances of polyhedral scenes. Random instances of line drawings are then obtained as perspective projections of these scenes, and can be used as an input to standard labeling algorithms so as to derive experimental estimates of the complexity o...
The complexity of understanding line drawings of Origami scenes
 International Journal of Computer Vision
, 1996
"... This paper deals with the interpretation of line drawings of Origami scenes (Kanade, 1980), that is scenes obtained by assembling planar panels of negligible thickness, and it addresses the computational complexity of the problem of consistently assigning suitable labels to the segments describing 3 ..."
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Cited by 4 (0 self)
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This paper deals with the interpretation of line drawings of Origami scenes (Kanade, 1980), that is scenes obtained by assembling planar panels of negligible thickness, and it addresses the computational complexity of the problem of consistently assigning suitable labels to the segments describing 3D properties as convexity, concavity and occlusion (labeling problem). The main results of the paper are the following: (a) the labeling problem for line drawings of Origami scenes is NPcomplete, as for the case of trihedral scenes; (b) the problem remains NPcomplete even if the location of the vanishing points in the image plane is given, whereas for trihedral scenes the problem was polynomially solvable; (c) in case the vanishing points are known the labeling problem can be subdivided into two subproblems, the paneling problem and the labelingapaneledlinedrawing problem which are both polynomially solvable. The approach provides geometrical constraints which help select `natural' in...
Algebraic polyhedral constraints and 3D structure from motion
 Proceedings of the 5th Alvey Vision Conference, Reading
, 1989
"... We describe the application of algebraic polyhedral constraints to the computation of the 3D structure and motion of polyhedral objects. The method, which works when complete 2D linedrawing information is available, guarantees the recovery of planar faces. The normals to these faces are used for mat ..."
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Cited by 2 (0 self)
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We describe the application of algebraic polyhedral constraints to the computation of the 3D structure and motion of polyhedral objects. The method, which works when complete 2D linedrawing information is available, guarantees the recovery of planar faces. The normals to these faces are used for matching to models. Several examples are given to illustrate the scope of the method. In [1] Murray et al. describe a motion processing system, ISOR, which is able to recover the 3D motion and structure of polyhedral objects from an image sequence and goes on, where possible, to recognize the object as one from a database of object models. The system performs a 'bottomup' pass through a vision processing hierarchy in the four stages: (i) Low level Compute visual motion at intensity edgels in a sequence of timevarying imagery; (ii) Segmentation Segment the edgels (and thereby visual motion) into
Geometrical constraint based 3D reconstruction using implicit coplanarities
"... Coplanarity is a relationship of a set of points that exist on a single plane. Coplanarities can be easily observed in a scene with planer surfaces, and these types of coplanarities have been widely used for 3D reconstructions based on geometrical constraints. Other types of coplanarities that can b ..."
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Cited by 2 (0 self)
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Coplanarity is a relationship of a set of points that exist on a single plane. Coplanarities can be easily observed in a scene with planer surfaces, and these types of coplanarities have been widely used for 3D reconstructions based on geometrical constraints. Other types of coplanarities that can be observed from images are those observed as cross sections of planes and scenes; for example, points lit by a line laser, or boundary points of a shadow of a straight edge. Although these types of coplanarities have been implicitly used in variations of light sectioning methods, they have not been used in an unified manner with the former types. In this paper, we describe a new 3D reconstruction method based on coplanarities and other geometrical constraints. In particular, we make use of the above two types of coplanarities in an unified manner. This enables us to reconstruct 3D scenes scanned using line lasers or shadows of straight edges observed by a partiallycalibrated single camera utilizing geometrical relationships between the planes in the scenes and the planes of line lasers or the planes of shadow boundaries. 1
Structure and Motion from Line Segments in Multiple Images
 IEEE Transactions on Pattern Analysis and Machine Intelligence
, 1992
"... This paper presents a new method for recovering the three dimensional structure of a scene composed of straight line segments using the image data obtained from amoving camera. The recovery algorithm is formulated in terms of an objective function which measures the total squared distance in the ima ..."
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Cited by 2 (0 self)
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This paper presents a new method for recovering the three dimensional structure of a scene composed of straight line segments using the image data obtained from amoving camera. The recovery algorithm is formulated in terms of an objective function which measures the total squared distance in the image plane between the observed edge segments and the projections (perspective) of the reconstructed lines. This objective function is minimized with respect to the line parameters and the camera positions to obtain an estimate for the structure of the scene. The effectiveness of this approach is demonstrated quantitatively through extensive simulations and qualitatively with actual image sequences. The implementation is being made publicly available. Keywords Structure from motion, straight lines, threedimensional reconstruction, perspective projection, numerical minimization. I.
Exploiting tjunctions for depth segregation in single images
, 2009
"... Occlusion is one of the major consequences of the physical image generation process: it occurs when an opaque object partly obscures the view of another object further away from the viewpoint. Local signatures of occlusion in the projected image plane are Tshaped junctions. They represent, in some ..."
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Cited by 2 (0 self)
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Occlusion is one of the major consequences of the physical image generation process: it occurs when an opaque object partly obscures the view of another object further away from the viewpoint. Local signatures of occlusion in the projected image plane are Tshaped junctions. They represent, in some sense, one of the most primitive depth information. In this paper, we investigate the usefulness of Tjunctions for depth segregation in single images. Our strategy consists in incorporating ordering information provided by Tjunctions into a region merging algorithm and then reasoning about the depth relations between the regions of the final partition using a graph model. Experimental results demonstrate the effectiveness of the proposed approach. Index Terms — Image Segmentation, Tjunctions. 1.
nD Polyhedral Scene Reconstruction from Single 2D Line Drawing by Local Propagation
, 2005
"... Abstract. In this paper, we study the problem of reconstructing the polyhedral structures and geometric positions of a general nD polyhedral scene from a single 2D line drawing. With the idea of local construction and propagation, we propose several powerful techniques for structural reconstruction ..."
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Cited by 1 (0 self)
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Abstract. In this paper, we study the problem of reconstructing the polyhedral structures and geometric positions of a general nD polyhedral scene from a single 2D line drawing. With the idea of local construction and propagation, we propose several powerful techniques for structural reconstruction (i.e. face identification) and geometric reconstruction (i.e. realizability and parametrization). Our structural reconstruction algorithm can handle 3D solids of over 10,000 faces efficiently, outperforming any other existing method. Our geometric reconstruction algorithm can lead to amazing simplification in symbolic manipulation of the geometric data, and can be used to find linear construction sequences for nonspherical polyhedra.