Formal specification of topological subdivisions using hypermaps

For robot manipulators, it is nowadays necessary to know their surroundings. This knowledge consists at least of a world representation with recognized objects. During the reconstruction of scene objects from multiple views, changes, like positioning of the objects, or additional unwanted signals, like parts of a human co-worker, may occur. In this paper, we classify the possible changes for a specific type of representation (boundary representation models). Afterwards, we present an approach to detect and handle these changes to maintain a valid world model. To achieve this, we compare what should be visible in the world model reconstructed thus far with the actual information from the current view. The detected change is handled by using object hypotheses as well as geometric information from the world representation. Based on an evaluation, we show a proof of concept and the usefulness of our approach and suggest future work.

This paper present a new method for automatic form feature recognition from boundary representation of a solid model. The proposed method is called the edge boundary classification technique. This technique uses the geometry, topology, and spatial information of a solid model for feature recognition patterns. Some aspects of edge boundary classification are discussed for recognising non-intersecting and intersecting form features.

Recently, concurrent engineering (CE) has become one of the major conceptual approaches in reducing product developing time. Design for manufacturing (DFM) and design for assembly (DFA) are two of the major areas in CE. Several researchers have integrated a CAD/CAM system and a knowledge-based system to implement DFA and DFM concepts. However, the incompatibility of the data representation methods between CAD/CAM and knowledge-based systems is the major issue in this integration method. In this paper, an approach is proposed to find the minimum wall thickness of a part from its boundary representation (B-Rep) model. These data can then be directly utilized by a knowledge-based system to analyse the manufacturability of thin wall parts such as injection moulded or diecast parts.

Loops are critical elements in boundary representation (B-rep) models because they link all edges corresponding to a face. Loops can be used in feature recognition for identifying depressions or protrusions. In real 3D CAD models, however, features typically lie across multiple faces, which is beyond the data structure of current B-rep models. This study presents a virtual loop concept to account for all loop types used in CAD models, and develops algorithms for recognizing them. In accordance with the complexity of the recognition algorithm, this study defines three types of loop: single, virtual, and multivirtual. A single loop is the current loop recorded in the B-rep model. A virtual loop lies across faces that are at least G1 continuous. Finally, a multivirtual loop lies across faces that are either G0 or G1 continuous. The proposed loop structure provides a more complete data structure for recognizing various types of features in feature-recognition modules. Several realistic CAD models are presented to confirm the feasibility of the proposed loop-recognition and feature-recognition methods.

Defects in boundary representation models often lead to system errors in modeling software and associated applications. This paper analyzes the model rectification problem of manifold boundary models, and argues that a rectify-by-reconstruction approach is needed in order to reach the global optimal solution. The restricted face boundary reconstruction problem is shown to be NP-hard. Based on this, the solid boundary reconstruction problem is also shown to be NP-hard.

After analyzing the characteristics of rock salt and the feasibility and importance of using underground rock salt cavern as energy stockpiles, this paper explains in detail about the principle of sonar detection technology in cavern measuring and its data organization. This paper studies the technology of three-dimensional surface topological reconstruction of underground rock salt cavern based on sonar detection data with half-edge data structure and boundary representation models. Meanwhile, by conducting validity check for constructed surface model and repair of possible defects, the paper finds correct and effective three-dimensional surface models of underground rock salt cavern, and provides effective data base for the stability analysis, creep analysis and other numerical simulations of underground rock salt cavern. This method, with important economic and social significance, can provide a scientific basis and technological support for the construction of caverns, especially for the safe and rational use of underground rock salt cavern.

This report gives an overview of the current status and plans to construct a prototype environment of advanced tools for software and hardware development based on the use of wide-spectrum languages. The wide-spectrum languages include Anna (ANNotated Ada), and TSL (Task Sequencing Language). The tools described here provide interactive aid at all stages in the system development process. Special emphasis is placed on distributed computing, both in providing tools for handling parallelism in the subject system, and in designing tools that utilize parallelism in the programming environment. Applications of these tools include requirements analysis, formal specification, rapid prototyping, testing, formal verfication and construction of self-testing Ada software for multi-processor systems.The report describes an existing environment of prototype tools supporting applications of Anna and TSL to formal specification and testing of Ada software. The new environment tools will be based on component tools already developed at Stanford and proven to be portable to various Ada environments. All tools are implemented in Ada and are intended to interface with standard components of Ada programming environments.

CAFE is the name of a network based environment now under development for supporting systematic creation, checking, verification, and maintenance of formal specifications. CAFE has an algebraic specification language called CafeOBJ as its main specification language, and adopts an algebraic specification paradigm as its foundation. CafeOBJ is a successor of the OBJ language, and has important new features for concurrency and behavioral specifications. Concurrency and behavior are specified based on rewriting logic and behavioral (hidden sorted) algebra respectively. These new features make it possible to provide powerful language constructs for formal object oriented specifications. CAFE is designed to be a network based environment. For sharing specification documents systematically over networks, a new document formatting language called Forsdonnet (FORmal Specification Document ON NETwork) is designed by extending HTML. Forsdonnet includes constructs for formal and informal specifications, commands for executing (prototyping) and cheeking/verifying CafeOBJ specifications, etc. Forsdonnet is designed to be based on already established standard network infrastructure components like HTML and Netscape Navigator. The paper gives an overview and design considerations of the CAFE environment, featuring mainly CafeOBJ and Forsdonnet languages.

3D imaging has become a standard tool in medical diagnostics and, while software is available to visualize volumetric data sets, we do not yet have software that can efficiently transform 3D scan data to solid models that are useful for engineering design and analysis. Why not? Currently, deriving solid models from 3D scans involves 3 steps: (1) segmentation: identification of voxels associated with the structure; (2) polygonization: computing a set of polygons that approximate the surface of the structure; and (3) repair: removing stray voxels and polygons, specifying connectivity, and establishing consistent orientation. Significant progress has been made on accurate, automated segmentation (recent work by Hu et al. (Image Segmentation and Registration for the Analysis of Joint Motion From 3D MRI,” Proc SPIE 6141, pp. 133–142, Medical Imaging: Visualization, Image-Guided Procedures, & Display, 2006), combining graph cuts with level sets is of particular interest) but effective polygonization cannot be guaranteed. In the worst case, manual repairs are needed to patch holes and remove stray elements. Even if a valid boundary representation (b-rep) model is obtained, accurate models contain so many polygons that modeling operations become unfeasible. Moreover, regardless of accuracy, the surface of a polyhedral model will never be truly smooth. In previous work (Storti, D., et al., Artifact vs. Anatomy: Dealing With Conflict of Geometric Modeling Descriptions,” SAE 2007 Transactions Journal of Passenger Cars: Electronic and Electrical Systems, Paper No. 2007-01-2450, Vol. 116, pp. 813–823, 2007), we proposed overcoming the barriers to creating solid models from 3D scans by employing a new solid modeling description, wavelet SDF-reps, that lies much closer to the native 3D scan format and eliminates polygonization. Here, we focus on the ability to produce models with smooth surfaces that are important for various biomedical simulations. For example, careful studies of joint function involve detailed modeling of ligament wrapping; i.e., connective tissue moving across bone surface as the joint configuration changes. Realistic behavior cannot be obtained if the ligament is snagging on or snapping across convex vertices of a polyhedral model. Similarly, haptic simulation of a catheter navigating through the circulatory system cannot be realistic if the catheter gets stuck in concave vertices of the anatomical model. How can the new modeling format address such issues? Wavelet SDF-reps take advantage of a by-product of the segmentation algorithm (Hue et al.) which converts the raw voxel intensity values to a grid of signed distance values. Applying an appropriate interpolant such as Daubechies wavelets (Daubechies, I., Wavelets, CBMS-NS Series in Applied Mathematics, SIAM Publications, Philadelphia, 1992) then produces an implicit or function-based (f-rep) solid model of the segmented structure. Wavelet SDF-reps are inherently multi-resolution and support significant data compression and medial axis computation. We illustrate the capability of wavelet SDF-reps to support smooth models and enable analysis of curvature features.

Current reverse engineering systems can generate boundary representation (B-rep) models from 3D range data. Such models suffer from inaccuracies caused by noise in the input data and algorithms. The quality of reverse engineered geometric models can be improved by finding candidate shape regularities in such a model, and constraining the model to meet a suitable subset of them, in a post-processing step called beautification. This paper discusses algorithms to detect such approximate regularities in terms of similarities between feature objects describing properties of faces, edges and vertices, and small groups of these elements in a B-rep model with only planar, spherical, cylindrical, conical and toroidal faces. For each group of similar feature objects they also seek special feature objects which may represent the group, e.g. an integer value which approximates the radius of similar cylinders. Experiments show that the regularities found by the algorithms include the desired regularities as well as spurious regularities, which can be limited by an appropriate choice of tolerances.

The concurrent engineering approach is getting more popular in the product development process, and thus it becomes crucial to effectively share the shape information between the various people and the systems in a distributed design environment. There have been many previous researches to efficiently transmit and handle the geometric data, but still the transmission of geometric data is a time-consuming task and results in the inevitable latency.We introduce the level-of-detail concept into the transmission of boundary representation (B-rep) model to cut down the latency. The original model is broken down into small fragments in the level-of-detail generation step, and the transmission sequence of the data fragments is efficiently scheduled according to their contribution to the shape details. This approach is very attractive when transmitting very complex parts and assemblies, because the user can capture the overall shape at the earlier stage of the transmission.In this paper, a new level-of-de...

Solids are 3D models that are used to represent objects in 3D space. Examples of simple solid primitives are cubes, cylinders, cones, spheres, etc. There are many techniques developed in the literature to construct solids in 3D space. These techniques can fall under certain categories (Requicha in ACM Computing Surveys 12(4):437–464, 1980; Foley et al in Computer graphics: principles and practice in C. Addison-Wesley, Boston 1995). Among these categories are constructive solid geometry, primitive instancing, cell decomposition, spatial enumeration, different tree representations, translational and rotational sweep representations in addition to boundary representation and polygonal modeling. In this chapter, we will discuss some of these solid modeling techniques.

Octree reinforced thin-shell rapid prototyping

Presents Mosaico, an integrated environment conceived to support the design and specification of object-oriented database applications. Mosaico assists the designer in producing a formal and correct specification of the application domain in the form of a conceptual schema, a conceptual model of the application functions, and, finally, an executable prototype of the database application. The conceptual model of the database application is constructed by using the design language TQL++ (Type and Query Language++). The resultant TQL++ specification is semantically verified based on the theory underlying TQL++. Furthermore, through rapid prototyping, the TQL++ specification can be functionally verified. Semantic verification guarantees the correctness of the specification within the realm of the formal theory of the language. However, it does not guarantee the fidelity of the specification to the real world requirements (i.e. what the users really want). Rapid prototyping and functional verification are a means to bridge that gap. >

This paper discusses an experimental lightweight object oriented environment aimed towards the rapid prototyping, testing and deploying of distributed IN services using CORBA. Well-known design patterns have been adapted to implement as well as interwork with CORBA enabled components. Synchronous calls are used for CORBA object requests, while reliable asynchronous delivery such as that needed for all protocol specific transmission is provided via a minimal core subset of an event-based framework known as OVOPS. Thus, no additional CORBA service for messaging or event-handling is needed. The described environment will ensure the consistent creation of IN services as well as needed protocols through reusable object-oriented components communicating over a heterogeneous network. The IN services created would become independent of the underlying protocol which is used to communicate with the other service entities across the network, providing the advantage of being able to run the service over multiple protocols by isolating network specific information flow from service specific information flow.KeywordsIN Service Creation FrameworksDistributed Component-based SystemsDesign PatternsCORBA