描述目标的数据结构
1. struct
how to describe one object attribute. use a struct to represent one object, the struct include object state, dimension, id , yaw
2. array/vector
how to describe objects list. use a array or vector to represent objects list.
3. pointer/smart pointer eg: make_shared
how to use a pointer to point to objects list
4. std::map eg: at first second count
at first second counthow to use a map structure to describe objects list from different sensors.
so while give a std::map, how to get the specific attribute.
