Flavors of SLAM: vSLAM vs. LIDAR
There are different flavors of SLAM, and knowing which one is right for you matters. Watch the video below as Chase breaks down vSLAM vs LIDAR, some advantages, and disadvantages.
LIDAR is a light sensor. It uses lasers that shoots in different directions gathering information about objects around it. This technology can be found in autonomous vehicles today.
A camera uses key features, making it great for visual data. This information is stored for later use when the object appears again.
Radar and LIDAR are similar technology. LIDAR uses light technology that gauges the distance of an object. Radar uses an electromagnetic wave that bounces back to the device. This is how police using radar guns can detect the speed of a vehicle. You might want to slow down!
There are a few types of LIDAR. Solid-state LIDAR uses an array of light to measure the return of the light. Rotating LIDAR uses a field of lasers (yes, a field) that spins to give a 3D view.
One advantage of LIDAR is an active sensing source, so it is great for driving or navigating at night. Camera’s do not have that capability, which limits them to the daytime.
One of the biggest disadvantages of LIDAR is cost. Although it has decreased significantly over the last few years, it is still costly, and more so than a camera.
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vSLAM vs LIDAR:
There’s a few different flavors of SLAM: LIDAR SLAM and vSLAM being a couple of examples. Usually, you’ll have an inertial sensor to tell you where you’re going. On top of that, you’ll add some type of vision or light sensor.
Usually, the light sensor that is used is LIDAR, and what that does is it shoots a laser in or many different directions, and it uses the return from the laser scan to match, essentially the geometry of the objects around you.
If there’s a type of building with certain cutouts that you’ve seen, or a tree or vehicle, LIDAR SLAM uses that information and matches those scans. It overlays them to essentially optimize the most likely situation you’ve been in similar to that.
Now, on the other hand with the camera, a camera uses key features. So again, kind of things like corners. But it can use different types of information than LIDAR can because of the visual data coming in.
Visual SLAM can use unique features coming from a camera stream, such things as corners or edges or other things like that. It stores the information that helps it to describe what that unique shape looks like so that when it sees it later, it can match that it’s seen that thing, even if it’s from a different angle.
LIDAR is a technology that’s similar to radar but with light. We all know how when you’re driving too fast and there’s a police watching, and they have their radar gun, and it shoots an electromagnetic wave and it bounces back. It measures how long it takes for that signal to return to know how far away you are and then they can calculate how fast you’re going.
LIDAR does the exact same thing, but with light. It shoots a laser that has a sensor that’s looking for that signal to return, and based on how long that takes, it can tell how far away something is.
Typically, there are a few types of LIDAR. There’s solid-state LIDARs that doesn’t have any moving parts but shoots out an array of light in different areas and measures the return. There’s rotating LIDARs that usually have a field of little lasers that spin and they’re shooting out light as they go. That gives you more of a 3d view all the way around you.
The big market that the LIDAR is in right is autonomous vehicles. You’ve probably seen with a lot of recent developments, the cars that are driving on the roads have these little circular or cylindrical on top that are spinning, and that’s LIDAR usually. Waymo, Uber, Ford stuff, GM’s Crews, pretty much everybody but TESLA is using LIDAR these days.
What are the advantages of LIDAR? One of the big things is it’s an active sensing source. It’s actually shooting out the light that it’s receiving back again. If you’re wanting to drive or navigate at night, that’s a big advantage because you’re not relying completely on daylight to do that. That’s one of the disadvantages the cameras have, pretty much you have to drive in the day.
Infrared cameras do a similar thing to LIDAR where they have a little infrared light that they shoot out and then they’re receiving it again. They have an infrared spectrum flashlight that they’re shooting out and sensing.
There are some disadvantages that LIDAR has and currently, the biggest one is cost. It’s a new technology. Previously it’s been extremely expensive, and that cost has come down a lot in the last few years, but still compared to cameras, it’s relatively high.
The other disadvantage is that while it does have a lot of information about the depth, it doesn’t have the other information the cameras have like color, which can give you a lot of really good and interesting data. It does have a reflectivity that’s similar. So sometimes cars can see lane markings basically based off of how reflective they are, but again, it’s not like a camera that has full color.
If you’re operating in any type of environment where GPS or any type of global positioning is either occluded or not at all available, vSLAM is something that you should look into.
If you want to learn more about vSLAM vs LIDAR or anything else that we’ve talked about, please just click the link below and we’ll get in touch with you.