Perception


Stay tuned for future updates!

Camera Perception
Radar Perception
LiDAR Perception
Sensor Fusion with LiDAR & Camera

AutowareAuto High-level Architecture of Perception Component


Camera Perception (Temporary Demo, AutowareClass2020)


Recap: Camera Model

\(D\): aperture diameter
\(f\): focal length
\(N\): aperture f-number (e.g., f/2.8, f/4)

$$D = \frac{f}{N}$$

A larger aperture diameter (smaller N) allows more light to enter the lens, affecting exposure and depth of field (DoF, not FoV directly). A smaller \(N\) (larger aperture) leads to a shallow DoF.

$$FoV = 2arctan(\frac{sensor\_dimension}{2f})$$

A longer focal length reduces the field of view (FoV).

Recap: Camera Matrix

\(K\): intrinsic camera parameters
\([R|t]\): extrinsic camera parameters
\(s\): extrinsic camera parameters
\(f_x,f_y\): focal lengths of the camera in the x- and y-direction in pixels
\(c_x,c_y\): principal point coordinates, \(c_x\) and \(c_y\) are close to the center of the image
\(p_i\): 2D image point in homogeneous coordinates \([u, v, 1]^T\)
\(p_w\): 3D image point in the world in homogeneous coordinates \([x, y, z, 1]^T\)

$$P = K[R|t] = \begin{bmatrix} f_x & s & c_x \\ 0 & f_y & c_y \\ 0 & 0 & 1 \end{bmatrix}[R|t]$$

$$p_i = \begin{bmatrix} u \\ v \\ 1 \end{bmatrix} = Pp_w = K[R|t]p_w = \begin{bmatrix} f_x & s & c_x \\ 0 & f_y & c_y \\ 0 & 0 & 1 \end{bmatrix} \begin{bmatrix} r_{11} & r_{12} & r_{13} & t_x \\ r_{21} & r_{22} & r_{23} & t_y \\ r_{31} & r_{32} & r_{33} & t_z \end{bmatrix} \begin{bmatrix} x \\ y \\ z \\ 1 \end{bmatrix}$$

Recap: Camera Len Distortion

  • Barrel distortion
  • Pincushion distortion
  • Mustache (complex) distortion
  • Radial distortion
  • Tangential (decentering) distortion

  • Radar Perception (Temporary Demo, AutowareClass2020)


    Radar can measure the distance, angle, velocity, and cross-section to/of objects to detect and classify different objects.

    Reference: https://www.renesas.com/en/blogs/why-do-we-need-radar

    LiDAR Perception

  • Drivers – translate raw data
  • Preprocessing – clean up inputs
  • Ground filtering – remove noise tutorial
  • Clustering – detect objects
  • Shape extraction – simplify representation

  • Autoware.Auto uses ray-based ground filtering because it is fast and deterministic.

    Object Detection & Recognition with LiDAR and Camera on GEM e4


    Reference

    [1] Perception Component Design, Link
    [2] Self-Driving Cars with ROS and Autoware, Link


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