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---
title: Camera Mathematics
categories: session
---
# Key Concepts
- calibration
- perspective
# Briefing
## World frame and camera frame
$$\mathbf{X} = R\mathbf{X}_0 + T\in\mathbb{R}^3$$
## Projection
$$ Z \begin{bmatrix}x\\y\\1\end{bmatrix} =
\begin{bmatrix}f 0 0 0 \\0 f 0 0 \\0 0 1 0\end{bmatrix} \cdot
\begin{bmatrix}X\\Y\\Z\\1\end{bmatrix}$$
Note that $Z$ is typically unknown.
We write $\lambda (=Z)$ for this unknown constant.
## Ideal Camera Projection
$$ \lambda \begin{bmatrix}x\\y\\1\end{bmatrix} =
\begin{bmatrix}f 0 0 \\0 f 0 \\0 0 1 \end{bmatrix} \cdot
\begin{bmatrix}1 0 0 0 \\0 1 0 0 \\0 0 1 0\end{bmatrix} \cdot
\begin{bmatrix}R T \\0 1\end{bmatrix} \cdot
\begin{bmatrix}X\\Y\\Z\\1\end{bmatrix}$$
$$ \lambda \textbf{x} = K_f\Pi_0\mathbf{X} = K_f\Pi_0g\mathbf{X}_0$$
## Ideal Camera Projection
## From meters to pixels
+ Same units for world frame and image frame, i.e. meter
+ Meaningless - images are measured in pixels
**TODO** complete
# Exercises
# Debrief