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Draft: Initial value in simplified_velo_kalman_filter not correct.

Zhihong Shenrequested to merge
zhshen into master

We found a bug in Allen/device/velo/simplified_kalman_filter/include/VeloKalmanFilter.cuh related to the Kalman filter initialization.

In the kalman filter, we skip the first hit, and start to filter from the second point.
Knowing the information from the first hit, the initial x and y errors should be pixel_error^2. However, in the code, they are set to 100f., which is much larger.

We found this bug by looking into the chi2 evolution:

  • expected: the chi2 is significantly different from 0, at the third filter process (adding the third hit).
  • observed: the chi2 is still very close to 0, at the third filter process.

This bug should have a large impact on the tracks with fewer hits.

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