Design And Implementation Of Content Based Shape Search Platform

Along with the rapid advancement of computer aided design modeling which is supported by the development of software and hardware, huge amounts of 2D/3D models have been created. Because of time consuming and many efforts involved in creating high quality 2D/3D, considerable resources could be saved if these models could be reused. It becomes an urgent request, for this reason, to develop a technology to retrieve 2D/3D models from a library. However, text based keyword retrieval method cannot satisfy CAD users anymore. In order to solve this deficiency, new method has been experimented and testified, that is, content based shape search retrieving models via building shape index and matching shape features, break the limitation of text based search. To be more specific, content based shape retrieving of 2D/3D models outperforms text based retrieving on matching precision.This thesis introduces the concept and key technology of general search engine, deconstructs the prototype of 3d search engine developed by Princeton. The components and functionality of basic modules a graphic search engine should possess has been elaborated via many aspects of the prototype system, i.e. design methodology, operating principle, human-machine interface, architecture, data flow as well as application logics. It is good theoretical foundation of this search platform. The main user groups of the shape search platform described in this thesis are mechanical engineer and structural engineer. This thesis analyzes user's requirements, sets the design objectives from business logic perspective and implementing perspective. From business logic perspective, basically the platform should provide user content search, content access and use. From implementing perspective, the platform should have good retrieval performance, flexibility, extendibility and maintainability.To accomplish these objectives, this thesis adopts framework/plug-ins model. Vertically, framework is broken into UI layer, business logic layer and data access layer. Horizontally, the capability of the platform can be extended dynamically at run time. i.e. the capability of indexing and retrieving a new format of shape file can be built into platform in this way. The object-oriented techniques has been used for the design of database schema, it brings system more flexibility and extendibility. The data exactors wrap up the API of CAD applications, to identify geometric features of shape files, and then index engine creates shape descriptors for shape files based on geometric features and put shape descriptor value into full-text index. Search engine provides shape search, range search and text based keyword search via full-text index matching. The shape search platform is built to provide several multiple search methods. To let the system have better usability, extendibility and generality, the platform exposes uniform search interfaces via web service. Clients just need to pass a XML string which describing search conditions as a parameter to search interface. Server will parse the parameter, invoke search engines accordingly, and return search results to client sides finally. In addition, this thesis has introduced a paging algorithm to address search results and use ASP.NET cache service so as to improve overall performance of the system.The author tested the shape search platform. The result proofs that the functionality and performance of search platform match system design objectives.