Add feedback during monocular initialisation to diagnose initialisation status

[martinakos]

What issue is the feature request related to?

Add feature tracks during monocular initialisation as feedback to diagnose initialisation issues.

Describe the solution you'd like

As I describe in this discussion https://github.com/stella-cv/stella_vslam/discussions/557 I'm experiencing very long monocular initialisation compared with ORBSLAM2 in the same conditions. I would like to see the same feature tracks that ORBSLAM2 shows during monocular initialisation to discard that the long initialisation is due to bad feature tracking. stella_vslam doesn't show these feature tracks during monocular initialisation so I don't know if the issue is bad feature tracking or how these tracks are used to initialise the map.

[ymd-stella]

I don't think the addition of the drawing feature will solve that problem. what you really need is a status indicator.

You can implement the following. (The related code is attached.)

• Get the reason why initializer returns false
  • https://github.com/stella-cv/stella_vslam/blob/1cf42b9589cf625008901f880963dca1b6409d52/src/stella_vslam/initialize/base.cc#L64-L86
• Set it to frame_publisher
  • https://github.com/stella-cv/stella_vslam/blob/1cf42b9589cf625008901f880963dca1b6409d52/src/stella_vslam/publish/frame_publisher.cc#L148-L163
• Get it and display it as status in viewer
  • https://github.com/stella-cv/iridescence_viewer/blob/3dc801bc284cf0e54b806ac8e1887dffe90620db/src/viewer.cc#L62-L63