Assembly Model Retrieval With Earth Mover's Distance Metric

Assembly product includes more enriched design knowledge such as connection relationship between parts,assemble order and assemble function than single part.The speed and accuracy ratio of existing assembly model retrieval still need to be improved.Quickly retrieving and making full use of existing assembly models have become a research hotspot of realizing rapid product design.An assembly retrieval approach with part attribute and location information was studied.Considering part information such as volume,surface area and spatial location can be obtained through CAD software directly,those information were directly used to describe the corresponding part in assemblies,which participated in calculating attribute similarity matrix between assemblies.Then the matched parts set was acquired with the Priority Match(PM)algorithm.Calculating the spatial local similarity of the matched parts and combining with the attribute similarity,the final similarity between two assemblies was obtained.Parts' shape distribution vector difference measured by Earth Mover's Distance(EMD)was alse used to realize assembly model retrieval.Sampling huge amounts of point-pairs from each part in assemblies to generate shape distribution vector as the correspoonding part descriptor.Aggregating all part shape distribution vectors together to form a set as the assembly descriptor.Then matching parts between two assemblies with EMD algorithm,in which process got the lowest matching cost as the dissimilarities between assemblies.An assembly retrieval method with parts' attributes vector difference metric by EMD was studied.The normalized attribute vector corresponding to each part model included in assembly was generated to aggregated together for forming a set as the assembly descriptor,and attributes information in the part attribute vector contains spatial location,volume,surface area and moment of inertia.Afterwards,the EMD method is offered to calculate the dissimilarity value between two assemblies,thus the assembly model retrieval was accomplished.Experiments show that the above algorithms enable efficiency assembly retrieval.And the assembly descriptor with part attribute vector set can be obtained directly without preprocessing.