test line break

line break

second

3rd

detaching: bottom chain-up not robust!

When bottom is broken, it becomes unrealistic to try to chain them all up by checking radial overlap.
It's much thinner than top-edges (hos).

So compared to detecting multiple strings of hos, detecting multiple bottom threads in multi-pieces is more challenging.

One way to chain bottoms up is to check angular overlap. Sort all bottom, count possible gaps into the angular span AS, in other words, only look at the start and end angles, see if it approaches the limit of the bbox range. But also count accumulated angular span AAS. If AAS(R) >> bbox_span(R), it's an attached groove.

Prerequisite: Bottom is captured in its relative entirety. So that we have enough stuff to accumulate.

Then how to get the strings of different revolutions within the attached-CC?

Stereo: sidewall interpretation

What we have:

• Sidewall 45 displacement gives a mono-decreasing left channel and a mono-increasing right channel

What does it tell us

• No oscillation found in sidewall displacement.
• This is wrong.
  
• Either we are getting some true information about some mono behavior
• Or some false combination cancelled out oscillation.

Analysis

• The former might be truer.
• The opposite trend b/w left and right is not coincidence, which is right, because left/right are of opposite sign in terms of sidewall movement.
  

Tests

1. Interp/resample edge first: using the raw fit
   
1. L+R, L-R
2. sidewall
   
2. Interp/resample edge first: using the diff fit
1. L+R, L-R
2. sidewall
   
3. Get sidewall at each raw point before resample then resample and interp
   

sidewall displacement

In Cartisian coordinate system [r, h] (i.e., [x, y]), if btm(t2) is below wall(t1),

then it's a downwards displacement.

stereo decoding

We have

1. Fitted data
2. Differentiation data

Theory

1. The displacement of the side wall in the norm direction, i.e., 45 degree to horizontal or vertical.
2. Left: inner edge, bottom
   
1. Horizontal: Positive direction: center -> brim
   
2. Vertical: Positive direction: upwards
3. Right: outer edge, bottom
1. Horizontal: center -> brim
   
2. Vertical: downwards
4. Wall movement is the vector sum of hori and vert: dH^2 + dV^2 = dW,
   
5. Sign of wall movement...
   

Reanalysis

1. Sidewall 45-degree system,
   
2. e.g. left = in norm direction, sidewall displacement
3. displacement = dist_point_to_line( bottom(t1), sidewall(t2)) * higher_than(z_bottom_projection, z_bottom)

Pitfalls

1. sidewall(t1) may not parallel sidewall(t2)
   
2. system error proportional to the position of the point representing the wall, when calc dist_point_to_line()

Polyfit error

In window 44-46, badly conditioned polyfit