There are several existing visual-inertial SLAM implementations. Among all, I pick okvis as our development basis. However, the okvis project is too well-written with sophisticated implementation. There are also some building problem. In summary, it is pretty hard for us to develop, especially from a very backend.
I decided to setup a new project based on okvis. I put it in my git repo. Currently, I finished the input of raw data, and parameter initialization.