bottom 1D from 2D wrong!

X: 1D bottom azimuth positions
Y: their index in original bottom 2D band

What's wrong here?

1. Some consecutive azimuths have same bottom 2D points (overlapped). They should have been monotonously increasing indices.
2. Instead, this curve means we will have "blur" problem if not angularly resampling/filtering carefully.
3. This also means, bottom thinning is problematic. Neither deepest-rule nor median-radius-rule would give us smooth continuous bottom trace.
   

How to solve this

1. resampling over each azimuth, if the tertiary has any overlap with the previous, it has to be discarded or adjusted to pair up other points.
2. we need to delay the fix? verify whether this fix will significantly improve sound quality?