Solid reconstruction using recognition of quadric surfaces from orthographic views

International audienceThe reconstruction of 3D objects from 2D orthographic views is crucial for maintaining and further developing existing product designs. A B-rep oriented method for reconstructing curved objects from three orthographic views is presented by employing a hybrid wire-frame in place of an intermediate wire-frame. The Link-Relation Graph (LRG) is introduced as a multi-graph representation of orthographic views, and quadric surface features (QSFs) are defined by special basic patterns of LRG as well as aggregation rules. By hint-based pattern matching in the LRGs of three orthographic views in an order of priority, the corresponding QSFs are recognized, and the geometry and topology of quadric surfaces are recovered simultaneously. This method can handle objects with interacting quadric surfaces and avoids the combinatorial search for tracing all the quadric surfaces in an intermediate wire-frame by the existing methods. Several examples are provided

Converting Hybrid Wire-frames to B-rep Models

International audienceSolid reconstruction from engineering drawings is one of the efficient technologies to product solid models. The B-rep oriented approach provides a practical way for reconstructing a wide range of objects. However, its major limitation is the computational complexity involved in the search for all valid faces from the intermediate wire-frame, especially for objects with complicated face topologies. In previous work, we presented a hint-based algorithm to recognize quadric surfaces from orthographic views and generate a hybrid wire-frame as the intermediate model of our B-rep oriented method. As a key stage in the process of solid reconstructing, we propose an algorithm to convert the hybrid wire-frame to the final B-rep model by extracting all the rest faces of planes based on graph theory. The entities lying on the same planar surface are first collected in a plane graph. After all the cycles are traced in a simplified edge-adjacency matrix of the graph, the face loops of the plane are formed by testing loop containment and assigning loop directions. Finally, the B-rep model is constructed by sewing all the plane faces based on the M¨obius rule. The method can efficiently construct 2- manifold objects with a variety of face topologies, which is illustrated by results of implementatio

Reconstruction of curved solids from two polygonal orthographic views

It has long been known that the 2-view orthographic representation of a mechanical part is ambiguous. Existing literature addresses the recognition/reconstruction of solids (mostly polyhedral solids) from either 1-view (perspective) drawings or from three orthographic views. The paper presents algorithmsfor reconstructing curved solids from only two polygonal orthographic views. First, all the polyhedral solids that correspond to the pair of prespecified orthogonal views are reconstructed, and then the associated third views are developed. Then, for each solid, the three views are analyzed simultaneously, and the authors reason about the possibilities of including circular arcs in the newly generated third view. This corresponds to the inclusion of solids that are bounded by quadrics. Possible application areas include computer-aided design, machine vision and automated inspection systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30171/1/0000556.pd

Sketching space

In this paper, we present a sketch modelling system which we call Stilton. The program resembles a desktop VRML browser, allowing a user to navigate a three-dimensional model in a perspective projection, or panoramic photographs, which the program maps onto the scene as a `floor' and `walls'. We place an imaginary two-dimensional drawing plane in front of the user, and any geometric information that user sketches onto this plane may be reconstructed to form solid objects through an optimization process. We show how the system can be used to reconstruct geometry from panoramic images, or to add new objects to an existing model. While panoramic imaging can greatly assist with some aspects of site familiarization and qualitative assessment of a site, without the addition of some foreground geometry they offer only limited utility in a design context. Therefore, we suggest that the system may be of use in `just-in-time' CAD recovery of complex environments, such as shop floors, or construction sites, by recovering objects through sketched overlays, where other methods such as automatic line-retrieval may be impossible. The result of using the system in this manner is the `sketching of space' - sketching out a volume around the user - and once the geometry has been recovered, the designer is free to quickly sketch design ideas into the newly constructed context, or analyze the space around them. Although end-user trials have not, as yet, been undertaken we believe that this implementation may afford a user-interface that is both accessible and robust, and that the rapid growth of pen-computing devices will further stimulate activity in this area

Automatic Construction of CSG Representation from Orthographic Projections

An algorithm has been designed to construct the CSG model of object from its 2D orthographic projections. The method proposed uses a top-down approach in which the existence of some 3D primitive (e.g. CUBE) is assumed and then different views are searched for appropriate elements to prove the assumption .The algorithm is applied to some examples and the results are demonstrated. A second algorithm has also been designed to implement the automatic input of line drawings. The drawings are first digitized using a high resolution scanner. After some preprocessing, the algorithm is applied to the image in order .to extract the relevant graphical elements, such as arcs and circles. Two examples are also demonstrated

Automatic Structural Scene Digitalization

In this paper, we present an automatic system for the analysis and labeling of structural scenes, floor plan drawings in Computer-aided Design (CAD) format. The proposed system applies a fusion strategy to detect and recognize various components of CAD floor plans, such as walls, doors, windows and other ambiguous assets. Technically, a general rule-based filter parsing method is fist adopted to extract effective information from the original floor plan. Then, an image-processing based recovery method is employed to correct information extracted in the first step. Our proposed method is fully automatic and real-time. Such analysis system provides high accuracy and is also evaluated on a public website that, on average, archives more than ten thousands effective uses per day and reaches a relatively high satisfaction rate.Comment: paper submitted to PloS On

3D model reconstruction from vector perpendicular projections

This scientific monograph deals with the issue of 3D model reconstruction of a rotation part from its orthogonal projections recorded on a digitalized drawing in vector format and with computer-aided automation of the process. The topic is a partial task of the domain focused on generating the 3D part model or product from a technical drawing. The introduction comments on the analysis of the current state of information in the field. The rules of projecting the parts in a technical drawing are described as well as the related terminology and methods in computer graphics, mathematics and geometry. The computer-aided ways of modeling solids are analyzed. The introductory part is complemented by an overview of existing solutions by other authors and by the possibilities of my own method development. The monograph core is focused on the proposal of proceedings and algorithms for transformation process automation of 2D vector record comprising orthogonal projections representing the rotation part on a 3D model. The pilot implementations of algorithms and their verification by testing on the selected sample of geometric shapes are added