Study Of Rapid Transmission In Internet And Version Management For 3D Model

The distributed collaborative design system (CDS) is one of the important development trends in the area of Computer-aided Design in the future with the development of information technology. In distributed collaborative design, the transmission of big-size 3D CAD model frequently occurs. However, because of the restriction of bandwidth, how to transmit the 3D model rapidly has been a problem needed to solve. In addition, the safety of model can not be ensured because it will be stolen easily form the public internet. In the other hand, because many designers design the same one model, they may modify the mode and many version files are created in the process of collaborative design. So it is necessary to find a method to manage the plenty of version files effectively and accurately.The following tasks have been achieved in this paper based on these above-mentioned reasons and the General Armament Department's 11th Five-Year important pre-project study: "** key technology of distributed collaborative design and manufacture network platform":(1) A rapid and accurate transmission method based on feature information extraction and features reconstruction for 3D model in internet is developed. The time and network bandwidth are greatly economized because only the small-sized neutral file (xml file) where the feature parameters and attributions are recorded is transmitted over the internet. Furthermore, due to the feature information is encoded in the neutral file so the security of file could be guaranteed. The received model has the same geometric topology information and feature parameters as the original model so the features could be edited arbitrarily. In addition, a new method is also developed to identify the topology entities through the comparison of geometrical and topological parameters in the process of feature reconstruction.(2) Secondary development of three-dimensional design software CATIA is implemented through the CAA and C++ to extract the feature information and rebuild the feature of CATIA model. The CATIA model files types which are developed not only Part mode but also Product model.(3) A difference analysis and merger algorithm based on feature semantic comparison for 3D model version file is proposed as a basis of achieving version management in collaborative design. Then the difference analysis of CATIA 3D CAD model files is developed. The case analysis shows that the two version files can be quickly analyzed and then merged which will effectively reduce the network traffic flow and ensuring transport security.(4) A prototype system is development to verify the rapid transmission method proposed. The test shows that this model transmission method can realize the rapid and accurate transmission for CATIA 3D Part model and Product model in CDS, and the equivalent transmission rate is higher when the model file is greater.The research in this paper will provide a method to optimize the CDS and accumulate much experience of development for CATIA which is provide widely in the aeronautics and astronautics.