
Livox Mid-40 lidar sensor - slimsag
https://www.livoxtech.com/mid-40-and-mid-100
======
dllu
Seems like the Mid and Tele are using Risley prism beam steering, which would
explain the hypotrochoid scanning pattern. [0]

They try to spin the scanning pattern as being an advantage as you get a more
dense sampling if you point at it in a certain direction, but I'm not
convinced. It is only an advantage if your device sits on a tripod. On a
moving car, more predictable, structured patterns such as the Ouster OS-1 [1]
make it much easier not only for deep learning, but also for SLAM (e.g. the
LOAM algorithm [2] extracts feature points row by row, i.e. by ring). For a
moving car or drone, any scanning pattern will sweep into a dense 3D point
cloud anyway.

The pricing seems to be competitive if you only need a small field of view.

For 360 degrees, it takes four Mid-100s, which would cost $6000, or twleve
Mid-40s, which would cost $7200, to obtain the same field of view coverage and
the same number of points (1.2 M points per second) as a single Ouster OS-1,
which is available to university researchers for $8000. However, buying a
single Ouster OS-1 saves you the headache of extrinsic calibration between
many lidar units, and the Ouster OS-1 only draws 14 W whereas four Mid-100s
would draw a whopping 480 W. Four Mid-100s also weigh twenty times as much as
one Ouster OS-1. For high density drone mapping, the Ouster OS-1 seems like a
much better choice.

That said, the Livox does have a range advantage over the Ouster OS-1.

[0] (PDF)
[https://www.thorlabs.com/images/tabimages/Risley_Prism_Scann...](https://www.thorlabs.com/images/tabimages/Risley_Prism_Scanner_App_Note.pdf)

[1] [https://medium.com/ouster/the-camera-is-in-the-
lidar-6fcf77e...](https://medium.com/ouster/the-camera-is-in-the-
lidar-6fcf77e7dfa6)

[2] Zhang, J., & Singh, S. (2014, July). LOAM: Lidar Odometry and Mapping in
Real-time. In Robotics: Science and Systems (Vol. 2, p. 9).

~~~
rosfan
As it is been pointed in the other reddit thread, the range should be a
comparison factor.
[https://www.reddit.com/r/SelfDrivingCars/comments/ahv796/liv...](https://www.reddit.com/r/SelfDrivingCars/comments/ahv796/livox_announces_lidars_for_autonomous_cars/)
Ouster has less than 50 meters while Livox has 90 meters, at 10% reflection.

------
purpleidea
Don't trust this thing. AFAICT, there's not a single clear photo of the actual
physical product. Everything is a rendering/CGI/dark lighting and I can't tell
if it's real.

If you had a working, quality thing, you'd expect they'd show a clear image.
Warning!

~~~
philtar
Isn't this it?

[https://store.dji.com/product/livox-
mid?vid=48991](https://store.dji.com/product/livox-mid?vid=48991)

~~~
joshvm
Usual caveat that you'll only get headline performance at 80% reflectivity,
maybe a number plate? Also the IP67 rating system doesn't cover the cooling
system (only IP55).

Hokuyo 2D systems start from about $1k and are well regarded in researcher.
SICK systems were historically used on research autonomous vehicles (eg the
grand challenges), but they're far too heavy for drone use.

Edit - I thought it was 1D initially, apparently the scan pattern is circular,
think spirograph (or a lissajous). You'd normally do this with galvos, but
this seems to be solid state.

~~~
rosfan
the specs has this 90m@10% 130m@20% 260m@80%

[https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/d...](https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/downloads/Livox%20Mid-40%20QSG%20v1.0%20multi.pdf)

------
kken
All specs are defined for 80% reflective objects? What do they assume here? A
retroreflective street sign?

Unfortunately there are no standards (yet) to benchmark different LIDAR
solutions, but most of their competitors stick to more realistic assumptions.

Then, in general, the website is light of any tangible information:

\- Company information: Management, History, Size, Investments, strategic
partners, location of company

\- Concrete working principle of their LIDAR: Detector principle, wavelengths,
laser type used, means of scanning, optical aperture

\- Images of actual hardware

\- Does their price-tag still apply after they have managed to implement
proper functional safety processes and measures?

Very weak, especially considering how much competition is out there. There
seems to be a new LIDAR start up every other weak.

~~~
italophil
Retroreflective road signs get close to 100% light returned and are a problem
for most LIDARs because they blind the sensor. Some companies are working on
car paint with higher visibility for LIDAR systems
([https://automotive.basf.com/news/read/improve-lidar-
detectio...](https://automotive.basf.com/news/read/improve-lidar-detection-
with-near-infrared-reflective-dark-automotive-paint-colors)) but that seems
the wrong approach to me. The LIDAR needs to work with legacy infrastructure
and nature.

~~~
cptskippy
Exactly. We'll never be entirely "legacy" free and it will take 30 years or
more to replace legacy infrastructure and vehicles.

~~~
grogenaut
I'm currently thinking through and costing out converting a classic pickup to
EV / more modern control systems. It may not last 30 years but it's not
getting self driving anytime maybe ever... and all the stuff we're making now
is legacy.

Just pricing out some 98-'02 hondas and acuras for daily mileage gobblers as
well, they're insanely cheap and pretty reliable. This is a 20 year old car
that is in high availability very very cheap ($1700 in seattle), and I hvae no
complaints about driving.

30 years may be optimistic except that the kids aren't learning to drive as
much being the down pressure.

Super cool that this stuff is getting into pricing ranges reachable by mere
mortals.

------
anotheryou
$600 for 360d coverage or for ~1/10?

edit: for just one: [https://store.dji.com/de/product/livox-
mid?vid=48991](https://store.dji.com/de/product/livox-mid?vid=48991)

~~~
DoctorOetker
38.4 deg x 38.4 deg (circular) according to manual

------
sbr464
Here's the manual
[https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/d...](https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/downloads/Livox%20Mid%20Series%20User%20Manual%20EN%2020190118.pdf)

~~~
Animats
That's helpful. The scan pattern looks like they have an oscillating radial
scanner plus a rotational scanner. I tried to build something like that once,
using an military surplus Bulova resonant scanning mirror for the radial axis
and a prism from a laser printer for the rotating axis. 1990s, before you
could buy anything useful in a LIDAR. Never got very far.

You can do this, but unless it's super cheap, why? Price/performance isn't
that good.

~~~
sbr464
I think it mentioned it’s solid state, less moving parts but I’m not positive.
I ordered one to test so I’ll post back.

~~~
rosfan
in the video, they mentioned there is no moving electronics parts. NOT no
moving parts. I think they mean no slip-ring kind of easy-to-fail parts, which
is necessary to connect the power and signal for rotating electronics.

~~~
sbr464
Exactly, if it would of had solid state tech, I’m sure they would of mentioned
it, that’s why I was unsure. It’s interesting to see the raw, competitive, old
snake oil tactics in such a bleeding edge, socially useful, new technology. I
cry a little for humankind.

------
zevv
Slightly off topic, but still some questions that have been bothering me for a
while:

LiDAR for autonomous vehicles is cool and all, but how will this perform if
there is not the occasional car making test runs through town, but when all
vehicles on a busy road or intersection are equipped with a one or more units?

I understand that both radar and ultrasonic suffer from interference, so will
this be different?

Are there plans for doing any kind of (cooperative?) frequency or time
division to avoid interference between cars?

How DOS-able would LiDAR be? Would I be able to bring traffic downtown LA to a
halt in 2040 by bringing my portable LiDAR jammer?

~~~
baybal2
> How DOS-able would LiDAR be? Would I be able to bring traffic downtown LA to
> a halt in 2040 by bringing my portable LiDAR jammer?

Even that will not be necessary, a splat of dirt on the sensor is enough.

I don't understand their obsession with LADARs. MM wave radars were
successfully handling the same task in the industry for a few decades while
being much cheaper and reliable.

NIH too strong. I feel calling that here is 100% appropriate and objective.

~~~
Symmetry
Radar is very useful but doesn't replace a lidar. Radars give very accurate
readings of an objects distance and relative velocity but very poor angular
resolution. For that reason they aren't much use for avoiding stationary
objects since those are hard to distinguish from the ground, signposts, etc.
At least until they get so close that the radar field of view lets you rule
out those things.

They are really great at figuring out whether cars are braking, though, since
cars are moving with respect to the ground you can just filter the ground out
and with radar you can sense the change in speed directly rather than having
to figure out the speed by comparing distance over time.

EDIT: Actually, I think automotive radars don't give any directional
information at all since they don't use big dishes. I'm used to working with
aerospace radars but even with those I wouldn't rely on one for car
navigation.

~~~
baybal2
> Radar is very useful but doesn't replace a lidar.

It does, and quite well. Without any additional processing, you easily get few
cm accuracy, and sub-wavelength resolution is possible if you do. That's more
than enough.

Latest automotive radars use electronic beam steering – not much different
from what is used in latest missiles.

I'd say, companies opting for ladars for driving assists don't have good
engineering expertise.

~~~
Symmetry
The range resolution in cm is very good but the angular resolution in radians
basically doesn't exist.

------
fest
The agreement you have to agree with is very interesting:
[https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/d...](https://www.livoxtech.com/3296f540ecf5458a8829e01cf429798e/downloads/No%20Resell%20clause.pdf)

Does such an agreement have a legal force (in US/EU)? I get the patent laws
and not violating the IP, but I find it strange that just the curiousity of
seeing how it works can get lawyers attacking you.

~~~
JoeAltmaier
Right I agree. What's that part about agreeing not to sell/resell? I can do
what I damn well please with my property.

~~~
late2part
Sort of.

 _Earlier this year, the Tenth Circuit court upheld a preliminary injunction
granted in favor of an electronics equipment manufacturer against a reseller
of its goods in a trademark infringement action. In Beltronics v. Midwest
Inventory Distribution, the reseller (Midwest) argued that it was able to
resell the manufacturer’s goods based on the first sale doctrine. The court,
however, disagreed with this assessment and ruled that the resellers violated
the manufacturer’s trademark rights because Midwest’s sales caused consumer
confusion._

[https://www.theiplawblog.com/2009/12/articles/trademark-
law/...](https://www.theiplawblog.com/2009/12/articles/trademark-law/when-
product-resales-are-not-protected-under-the-first-sale-doctrine/)

~~~
tooop
That is a totally different case because reseller was removing serial numbers
from products which in return invalidated any support from Beltronics.

------
m0zg
>> 130 meters with 20% reflectivity.

Isn't our perception of "reflectivity" essentially logarithmic? What we
perceive as the "middle" between black and white only reflects 18% of light.
Meaning anything that's darker than gray will be exponentially less reflective
than that.

~~~
kyzyl
If you're talking about how the human eye perceives light or dark objects,
then yes it can be more complicated. Especially when colour is involved. That
said, what they're talking about here when they say 'reflectivity' is the
ratio of the power returned from an object to the power you shined onto it
with your laser. The reflectivity will depend on the object surface texture,
material, wavelength of light etc., but it only loosely corresponds to what
you perceive as bright or dark.

The metric really just reflects (:-D) the signal-to-noise ratio and dynamic
range of their sensor. Max range, min/max reflectivity, SNR, accuracy, and
everything else are all intertwined, so it's very difficult to compare things
on equal footing unless you know exactly how it was measured. LIDAR OEMs seem
to have settled on a 10%/80% rule of thumb.

~~~
m0zg
My point is, I'm not sure if 20% is actually a good threshold to be measuring.
What are the levels of reflectance that will be encountered in practice? I.e.
if a car is black (or splattered in dirt), what percentage are we talking
about? Visually a lot of cars on the road are darker than "middle gray".

~~~
kyzyl
Amusingly, the question of "where to set the threshold" is actually a problem
for pulsed lidar in general. What constitutes the pulse returning, and how do
you know which pulse is dominant? In any case, my point was that I don't think
they are implying that 20% is "the one true threshold" that determines if a
LIDAR is sensitive enough. Indeed, many OEMs specify the bottom bracket at 10%
already, and there will always be other variables such as weather and texture
that will ruin your day no matter what threshold you chose.

As with software performance, it's all about reasonable benchmarking. If
you're in some lidar application, for example building a self driving car, and
you currently use velodyne HDL-64 sensors that can register returns from 10%
targets at 80m, then Livox's specifications give you a clue as to how their
unit might compare in a similar circumstance. That's all. Past that, you have
to rig up a test with the unit yourself and profile, it's the only way. I'd
also add that many objects would appear different in brightness if you looked
at them under a pure wavelength like 905nm, rather than the while light your
eye sees.

All that said, your concerns aren't misplaced. One of the leaders in the 'new
wave' lidar OEMs is Luminar, and one of their original value propositions was
that they went to a different wavelength (1550nm) which has a higher eye-safe
power limit. This means that they could pump out higher energy pulses, and
thus get more photons back from low reflectivity targets such as tires and
dark cars. The jury is still out on what works best to cover the real world
range of reflectivities, largely because there are just a lot more variables
at play that a simple thresholding would imply.

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amelius
If this was about an aerospace application, I'm sure this sensor would have to
be redundantly installed. So why do they/we assume a car needs only one of
these sensors?

~~~
dllu
What makes you think a car just needs one? Many of their videos on the website
suggest surrounding your car with a dozen of those sensors with overlapping
fields of view.

~~~
amelius
You are right. I guess I took my assumption from the Waymo cars which have
only one sensor on top of the car (or so it seems).

------
unictek
Fully autonomous & killing drone will start here

