#005- Does mobile mapping displace terrestrial laser scanners. BLK2GO test!
Would Leica’s BLK2GO replace laser scanners and deliver valuable data?
Did you face time limitations in your projects? Let’s consider a job offer scenario where your potential customer wishes to have an update of the building documentation. This customer asks you for a laser scanning service price. Unfortunately, the price seems to be too high which could be afforded by your client. What to do then? Shall you dump the price or just drop this project?
MLS from Leica Geosystems
Thanks to Leica Geosystem Norway I had a chance to test out twice the Leica BLK2GO scanner. It is a lightweight, portable, and wireless handheld scanner for mobile mapping. It was announced in 2019 and released in 2020. It also won the Best of Innovation award at CES2020.
Is it as good as it is described in brochures? What about data quality? Can you use it for the purpose described in this article’s introduction? Let’s take a look deeper into this device and the possibilities it brings.
BLK2GO in 2020 — first look, first impression
In April 2020 was my first encounter with this device. First impressions? WOW! Size, weight, short initialization time and generally speaking mobility! My first thought was — perfect for any projects where I have to travel by plane. Easy to pack to your hand luggage and no extra cost in a project. You get the device, a total of 3 batteries which last for approx. an hour of continuous scanning, charger, USB cable, stand (which is useful during initialization of the device) and a plastic case for the scanner, and 2 batteries. As far as I remember you have to pay about 500$ for a soft bag to carry the entire set.
When I took it into my hands then I realized that the bottom part where are mounted cameras and handle is made of solid and pleasant in touch metal — anodized aluminum. Unfortunately, the top part which covers two LiDAR heads is made of plastic which I believe is the only way to have a semi-transparent coverage of the laser heads but gives a feeling of cheapness. It also worried me how robust is it and how any scratches would affect the quality of the data — especially possible when you would use it in industrial projects.
Let’s scan!
Leica seller gave me a really short introduction to the workflow and usage of the app. This time the BLK2GO live app was available only on the iOS platform and compatible with iPhones not iPads. Luckily it is available on iPads and Android devices as well! When the app was installed and ready to use, the first time popped up an error about connectivity with the scanner. Reset of the app and the device solved the problem. App connected correctly to BLK2GO and notified me about readiness by using colors yellow/green. I clicked the button on the scanner’s housing and the app informed me what to do next. I had to hold the device stable for a few seconds to initialize it and begin the acquisition process. I used the dedicated plate which has a small bolt that helps to place the scanner correctly on the plate and prevent unwanted moves. On the app appeared first collected points which meant I could walk and scan.
I tried to walk quite stable and with constant velocity. I was instructed to hold the scanner, not in front of me but a bit to the site so I would be out of range panorama cameras. During the acquisition, I could see the progress of the scanning in 2D which was helpful to recognize in the space what was covered and where I should walk to collect more data.
The APP
Let’s talk about the app. It is very simple and doesn’t give you an overwhelming impression. You can either scan or browse projects saved on the device. The scanning section lets the user observe the progress of the acquisition, jump between 2D and 3D view, and change the elevation of data presented currently on the screen. Unfortunately, when the user begins to manipulate the 3D view, the app loses the scanner’s position in point cloud space. It means that the view doesn’t recenter to the current BLK2GO position in 3D. The user has no possibility to recenter it as well. The view has to be switched to 2D and back to 3D to recenter and follow the trajectory. Another issue I observed happens when you scan more than one floor in a single project. The 2D view is not following the trajectory in Z-axis so when you let’s say go upstairs, the trajectory and the dot (indicating spatial scanner’s position) disappear. The view in the app still shows you the data from the floor below and not your current position. You have to change the view elevation manually by using a slider. During the scanning, you are also able to create geotags with a picture and some description which is useful in cases you know what you should focus on. The project created from your last walk gets the default name which you can rename later on.
The second portion of the BLK2GO Live App is browsing the stored projects and collected data. As I mentioned, here you can rename particular projects, change the thumbnail, and add a description. It is possible to check the data in 2D and 3D. Unfortunately, a 3D overview of the data is not really a 3D view. It is the kind of recording of the trajectory without the possibility to see entire data at once. It is perfectly shown in the video below.
Data acquisition
In 2020 I have done 10 walks/running with the BLK2GO in different environments: an office with glass walls and huge windows, a parking lot, an outdoor scanning in an urban environment, and a busy street. Short summary of the walks:
- The office area was scanned without any trouble. Some people were passing me from different directions. SLAM algorithm didn’t get crazy because of traffic, glass, or reflections.
- The parking lot was scanned smoothly. I tried slow walk approx. 1min and the same area I scanned jogging with BLK2GO — approx. 18 seconds.
- The first outdoor scanning failed either because of the glassy office walls or too few surfaces to use in SLAM. The second attempt I did between two buildings approx 25m away from each other. This time app didn’t throw the error.
- I tried several times to walk along the street. I had two buildings on both sides of the street — one glassy and one made of brick. Several attempts failed.
When I got BLK2GO in March 2021 into my hands, both firmware and the app were updated and worked much better and more stable. Then I could use the scanner for several days and I scanned the same areas as a year before and completely new places in total 40 walks from 3 to 25 minutes. The SLAM algorithm failed twice and quite unexpectedly, but I also occurred several other problems like LiDAR error or connection error.
Summary
First of all, I am going to write the second part of this review about the data quality and reliability. I will compare it with the data from other devices like Trimble X7, RTC360, or BLK360 and will take a look at the possible use of this data in the scan-to-BIM process. Stay tuned!
Generally speaking, the BLK2GO is a handy, robust, and simple-to-use device. Since 2020, Leica improved the firmware and the software which makes it more stable and pleasant to use. It still has some issues with odd and unexpected errors. The app needs some minor fixes and adjustments like recentering and 3D overview. The device itself is not so comfortable to use as backpacks solutions. Even though it is lightweight after a few walks you are going to feel your arm and your back. I am a rather trained person but I could feel my muscles the day after. That’s why came out some solutions like monopods or adapters to make life easier.
