Graphics Reference
In-Depth Information
d
LiDAR
Figure 8.6.
The time of flight of a laser pulse can be used to infer the distance to an object in
the scene.
LiDAR
Figure 8.7.
The phase shift of a sinusoidally-modulated continuous laser waveform can be used
to infer the distance to an object in the scene.
φ
can take tens of minutes with a pulse-based system — time that's precious on a
busymovie set, and raises the likelihood of significant changes occurring in the scene
during the scan.
8.1.2
Phase-Based LiDAR
A faster alternative technology that's even more accurate than pulse-based LiDAR
but has a smaller operating range is
phase-based LiDAR
. Instead of using the time of
flight of a pulse, phase-based systems use the amplitudemodulation of a continuous-
waveform laser, as illustrated in Figure
8.7
. A sinusoidal laser waveform is emitted
along the given ray into space; it bounces off a surface in the scene and the scanner
measures the phase shift
ψ
between the transmitted and received signals over the
round trip.
This phase shift is related to the time of flight
t
and the frequency of themodulating
sinusoid in radians
ω
by
ψ
=
ω
t
(8.2)
