# Regular Meeting (2020.6.1)

## Outline
* [Modified formula of Hough curve transformation](#Modified-formula-of-Hough-curve-transformation)

* Progress: Coding for Cluster

## Modified formula of Hough curve transformation

* Original formula:

    §3.2 Hough Transform 
    "Updated 2D Tracker Firmware Design for CentralDrift Chamber(CDC) at Belle-II", 
    M.C. Chang, K.Y. Chen, Z.X Chen, FJU ,2016 :

> $r = \frac{x^2 + y^2}{2xcosφ + 2ysinφ}$

* My 1st version: using $1/r$

$\frac{1}{r} = \frac{2(xcosφ + ysinφ)}{x^2 + y^2}$

* Cost of above aithmatic:
* polar space -> xy space -> Hough-Curve space

* Sara's version: I decide using in my program

    §5.1.2. Hough space parametrization
    "Track Reconstruction at the First Level Trigger of the Belle II Experiment", 
    Sara Pohl, FJU, 2017

> $\frac{1}{r} = \frac{ 2(cosφ_{TS} sinφ_0 + sinφ_{TS} cosφ_0)}{r_{ts} }$
> $= \frac{2}{r_{ts}} sin(φ_0-φ_{rs})$
> where $φ_0= φ + 90 deg$

* Cost of above aithmatic, improved by Sara :
* polar space -> Hough-Curve space

###### tags: `Regular Meeting` `DeWei`