Update visualizer code (#184)

* update vis backend

* update vis backend

* update vis backend

* update visualizer

* update visualizer

* update visualizer

* update featmap

* update featmap

* update visualizer and unitest

* add draw points unitest and refactor vis_backend

* fix typo and close unitest

* fix comment

* add docstring

* fix comment

* add master only

* fix comment

Co-authored-by: liukuikun <641417025@qq.com>