Lab05: Active Vision
There are 2 kinds of imaging: passive imaging where we sense the world,
and active vision where we sense how the world responds to active stimulus,
e.g. for active vision we may send out energy such as radio waves (for radar), sound waves (for sonar), or light (for lidar), and measure the response.
In this lab you will understand fundamentals of active vision by implementing
a very simple 1-pixel sonar system.
In this lab you will implement an extremely simple sonar system and demonstrate
an implementation of a SWIM (Sequential Wave Imprinting Machine) to show the
operation of the sonar, using whatever computer system you're most comfortable
with (e.g. laptop computer, smartphone, etc.),
as outlined in lecture 2023mar16th:
- 2/10 Send a steady sine wave through a loudspeaker and receive the return signal
from a microphone, with lowpass filter of the homodyne signal.
Plot the result as a green dot moving along one dimension on a
black background. Photograph the apparatus moving along a
straight path. Repeat at least 5 times and animate as a .gif file
to show the "sitting waves" effect;
- 2/10 Repeat for a square wave, i.e. multicomponent lock-in amplifier effect;
- 2/10 Repeat with complex-valued reference signal (e.g. cosines and sines)
and plot a red dot for the real part and a green dot for the
imaginary part, both moving along the same straight line.
Show animated .gif of complex-valued "sitting waves".
- 2/10 Repeat with a green dot only, but where the real part of the
homodyne signal moves the dot left-to-right and the imaginary part
moves the dot up-and-down.
Such a plane of plotting is called the "Argand plane" (or "complex
plane").
Photograph the result and show a .gif file with complex plane
moving along in time-exposure ("sitting wave" effect in extruded
complex plane).
- 2/10 Demonstrate multi-component extruded complex-plane, and show, for example,
Gibb's phenomenon and the effect of reflected sonar waves on it.