What is a laser scan?

- [Instructor] The focus of this course is on the ReCap Pro software, but since ReCap Pro uses data captured from laser scanning hardware I thought it'd be a good idea for us to at least do a quick overview of just exactly what is laser scanning. So laser scanning is just a process of capturing 3D reality using a laser scan device. Now how does that work? Well, I've gone out and gleaned together a definition of some key points here from a few different websites online and kind of summarized them as follows. So if you have a combination of controlled laser beams fired off in all directions and then combine that with a laser range finder to measure those distances then what you can do is take measurements in all those directions and combine them together to determine the shape and surface characteristics of objects, buildings, or landscapes. To create full 3D models you need to combine multiple scans taken from various vantage points and different viewing angles. So this is what laser scanning does. It uses laser technology to shoot off millions and millions of lasers in different directions and gather up millions of points and all those measurements and all those points together create something that we call a point cloud. So another site that I saw gave a good summary by saying it's almost like sonar with light. So if you think about boats and submarines that use sonar to help find their way and avoid obstructions in the water, they're using sound waves to measure the distances to objects. Laser scanning or LIDAR is just simply using light beams to do essentially the same thing. Now there's all sorts of hardware that supports laser scanning and by no means am I gonna do a comprehensive overview of all the hardware. I'm just gonna comment on a few of the devices that I've used to capture some of the exercise files and files that we're gonna be looking at here in the course. So the primary device that we were using in the capture of the files that I'll be sharing with you was a FARO device. It was a FARO X330 scanner and we also had an X350 scanner. Now some of the team also worked with Leica scanners and Leica software, so I thought I would mention them. They're also a very popular scanner manufacturer. And on one of the trips that I was on we actually had access to a Matterport device as well. So we were using that device. Now I've got a few websites to share with you. Just if you Google laser scanning or LIDAR you're gonna get all sorts of information. But if you search for LIDAR which is an abbreviation that stands for light detection and ranging, that'll probably refer to aerial laser scanning like this NOAA page here that is showing a bridge. And if you look at the illustration on the right there's an airplane that's actually got the device mounted on it so this is usually done with aircraft, either manned or unmanned aircraft, to make captures of very large site kind of projects, infrastructure projects and so on. Now no doubt you've either heard of or seen one of these cars driving around towns with the cameras mounted on top of the roof, Google Maps uses these to map their street view. These are another kind of LIDAR or laser scanning. They're capturing all of that surrounding settings and that's how they're creating those 3D environments that you see in Google Maps and some of the other maps like Bing maps and so forth. Now the FARO device that I mentioned moment ago, that's a terrestrial laser scanner, so it just simply means that it's ground based and it's also portable. So you take the device and you mount it on a tripod and you literally place it in different locations throughout the space. Now this is more appropriate for building scale type objects that you're capturing. You can capture entire buildings or individual rooms or spaces. So you literally pick up the device and move it around in order to capture multiple scans. So here's FARO's website, and specifically the FARO FOCUS page. And this was, again, one of the devices that we used quite extensively to capture a lot of our data. So just a quick look at their site. We also had access to the Matterport device. Now Matterport is not actually a laser scanner, per se. It uses something called structured light. So if I go to this page here I found this kind of interesting when I searched for different kinds of laser scanners. This page shows a nice diagram here that talks about the two primary ways that laser scans work. They either use the time of flight method or the phase method, the phased light method, so with time of flight it's literally using the constant of the speed of light and then how long it takes for the laser beam to bounce back and measuring that. The problem with that method is it's a lot slower because it has to wait for each beam to return and it may not seem like that should take very long since we're dealing with the speed of light, but considering that it needs to capture millions and millions of points, it actually does take a lot longer. The phased approach is kind of interesting because it takes advantage of the phase nature of light. So light is both waves and particles if you look in physics, and so the fact that there's a wave there they can send off laser beams in all directions and then measure the wavelength when it left the scanner and then measure the wavelength when it comes back and then compare the two and that helps them determine the distances, and that type of a scan tends to be quicker because they can send out the pulses in all directions at the same time. So two different types of technologies under the hood, and many of your scanner manufacturers create devices that work in both ways. The Matterport uses structured light, and the idea of this is the camera sends off a known pattern that if it was parallel to the projector from the camera then it knows exactly what the pattern should look like. But as that pattern wraps itself around 3D objects in the space at different distances and angles you then have another camera that reads it back and it can tell, based on the distortion in the image, what the 3D features are of that object. So it's still using a light-based technology. It's still, in a way, kind of like a laser scan, but it's just a different approach to doing it. So that's what the Matterport does versus what your more traditional laser scanner does. Now I also have the Leica page open here, specifically to the BLK360 page. So the reason I've opened this page is as I say, some members of our team did use some Leica equipment and technologies but also because the BLK360 has direct support for ReCap Pro on the mobile device. So if you have a BLK360 and an iPad Pro then you can actually run ReCap directly in the field on your iPad and register your scans in real time as you're capturing them. So it's kind of a nice, interesting technology, and definitely something to check out if you have access to this device. If you don't have access to this device it's fine because one of the benefits of ReCap is that it supports laser scan data from any device. I mean, that's one of its strengths, that's one of it's main features. So you can capture your scan data using any device that your firm has available to it. You don't have to go out and buy any special hardware, specific hardware, just whatever device you have access to, or you can even rent devices. And when you gather all that data back, ReCap will be able to read it, register it, process it, modify it. So I hope that overview just gives you a general idea of what we mean when we say laser scanning. Essentially what we're doing is measuring the distances of several laser beams across the 360 degrees in a space, and then compiling all those measurements together to create something called a point cloud. And that's the main thrust behind all of what we do in the ReCap software.