Change Anchor Boxes

[ahkarami]

Dear @kuangliu,
Thank you for your nice work. I want to change some of the anchor boxes' parameters in the box_coder.py. To this end, I have below questions:
1- How can I increase number of anchor boxes (i.e., increase another aspect_ratios for example 1/3.)?
2- Would you please explain how the scale_ratios are defined?
3- How can I increase number of anchor_areas (e.g., add 16*16.)?
Thank you