symbol

meaning

$\left(x_{\text{current},\text{center}},y_{\text{current},\text{center}}\right)$

brightness barycenter of tick mark

$G{A}_{\text{current},\text{tick-mark}}$

brightness average of tick mark

$G{A}_{\text{current},\text{background}}$

brightness average of tick mark's background

${\theta }_{\text{current},\text{tick-mark}}$

angle of $\left(x_{\text{current},\text{center}},y_{\text{current},\text{center}}\right)$ reference to $\left(x_{\text{instrument-cener}},y_{\text{instrument-center}}\right)$

$\Delta {\theta }_{\text{current}}$

difference between ${\theta }_{\text{former},\text{scale}}$ and its former tick mark

$D_{\text{current}}$

distance between $\left(x_{\text{current},\text{center}},y_{\text{current},\text{center}}\right)$ and $\left(x_{\text{center}},y_{\text{center}}\right)$