The Design And Implementation Of Offline POI Retrieval In Vehicle Navigation Software System

Car navigation software is widely used in people's daily life,and POI(point of interest)retrieval is one of the important functions of it.Most of the car navigation software can be networked and use online POI retrieval.Online POI retrieval function is very comprehensive,including search along the way and the surrounding search.In the offline case,the POI retrieval function is not good enough.On the one hand is the limitations of the hardware which can not match the server,on the other hand is the implementation of the program which does not take the online methods and use some simple search strategy.Today,the performance of the car is getting better and better,it is necessary to strengthen the function of offline POI retrieval.Zebra Network Technology Company recognized the problem of the offline POI retrieval,and started to redevelop a new offline POI retrieval.I have the honor to develop the offline POI retrieval system which refers to the online POI retrieval method to improve and enrich the offline POI retrieval.The POI retrieval system is divided into five parts:index construction,word segmentation and analysis,basic query,merge sorting and input prompt.The index construction module is mainly used for data maintenance side.When the data has a major update,it will reproduce data and push the data to user's car.The other four parts are used in offline POI retrieval system,they complete the POI retrieval system features.In this paper,the main functions of the offline POI retrieval are divided into three parts:the first part is the input prompt,trie tree is used to organize the index.The chinese characters and pinyin trie tree associated with each other achieve the prompt;the second part is the surrounding search and search along the way,Geohash coding index is used by trie tree,it can improve efficiency and achieve the function;the third part is the keyword query,Through the analysis of word segmentation and the synonyms,we build the query tree to organize the result.Based on the query tree,inverted index is used to query and get the POI results.At present,the offline POI system function has been improved and the efficiency is basically meet the requirements.From the test results,we find that the new offline POI retrieval system has more features,retrieval quality is also better.Of course,the offline search system have to do some product testing before it is used in the car.