For geospatial and surveying professionals, the evolution of mobile scanning technology has completely changed how teams work and process data in the field. Industries like construction, mining, and resource management are all taking advantage of the speed and flexibility that mobile scanning offers.
If you've been studying this technology for some time, or are just interested in exploring this changing field of LiDAR-based SLAM platforms and other various mobile scanners, you might be curious what to even look for when choosing a mobile scanner. What sensors are important for each use case? Don't mobile platforms drift? What do I do with the data after capture?
In this post we're going to take you through the 5 key things our experts and customers say are things to know when choosing a mobile scanner. We’ll also explain how these scanners work and how they compare to traditional surveying methods you’re already familiar with.
Terrestrial tripod lasers have been in use for some time and they provide a very accurate method for digitally surveying an environment so project managers, geologists, and others can interpret the captured 3D data and make critical decisions.
Terrestrial tripod scanners use laser light reflected from targets within the area to be mapped. A LiDAR system emits and receives the reflected laser light and then interprets that information into exact X, Y, and Z coordinates in 3D space.
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The problem is that each survey target is required to be manually shot in or larger areas can be scanned, but the sensor has to remain stationary throughout the process. Each scan only takes a few minutes, but when you're tracking hundreds or thousands of points across a project maintaining transparency about ongoing job progress the amount of time to capture each scan can quickly add up. The benefits of a mobile scanner is that you can be just that, mobile, while capturing an accurate map of an area of interest. But how is that possible? Let's look at the underlying technology that makes mobile mapping possible.
Simultaneous Localization and Mapping (SLAM) is the underlying algorithm that powers each Nexys mobile scanner. This enables it to build a complex map of an unknown environment while being moved freely, unlike a tripod-mounted terrestrial scanner.
Onboard Nexys, SLAM uses the LiDAR sensor as its eyes to continuously calculate incoming data to determine where it is and interpret any obstacles in its way. Then once a mobile capture is complete, ExynAI can quickly post-process the data into a high-density 3D point cloud, or digital twin.
And thanks to the modularity of the Nexys platform, it can move throughout an environment, either by hand, attached to a backpack, or mounted on an autonomous vehicle, and still get a highly accurate 3D map.
This gives you the flexibility to survey more often, which is critical for progress updates and monitoring work sites for changes. It also dramatically reduces the time it takes to conduct the initial survey.
Chances are if you're interested in mobile mapping you've heard that some data sets can accumulate drift over time that can affect the quality of the map and how it aligns to a global coordinate frame. This is the difference between local and global accuracy.
Local accuracy measures physical features within a 3D survey. For example, the distance between a wall and a support pillar inside of a building that’s being scanned. LiDAR SLAM systems are highly accurate for these types of measurements.
Visualization of a point cloud having accumulated drift eliminated through GCP anchoring
Global accuracy is where you match every feature of a 3d point cloud with a specific real-world coordinate frame such as GPS location data or a file of pre-surveyed ground control points (GCPs). In the early days of SLAM, the maps accumulated too much drift to be globally accurate. But with knowledge of SLAM best practices and by introducing further map constraints during post-processing, operators can confidently capture long, complex environments knowing they can maintain global accuracy across an entire project.
This gives geospatial professionals the flexibility and speed of mobile mapping with a similar level of global accuracy as tripod scanners.
During post-processing, the local map captured by the mobile scanner is adjusted to correct for any sensor noise or map inaccuracies to enhance and export a complete high-density 3D point cloud. This is also the step where operators can geo-reference a point cloud into a global coordinate frame.
As a mobile scanner like Nexys is moving through the environment, it is ingesting tons of data points to build a 3D model which can make moving and manipulating the final data file fairly cumbersome. And even then it takes a heavy computational load to process the data into a final 3D model.
Operator inspecting a point cloud playback after data capture.
As a result, most mobile scanners on the market require these data sets to be uploaded to a desktop or cloud application for processing. However, with Nexys operators can post-process large datasets on the same tablet used to visualize the real-time point cloud data as it is streamed to the platform.
There is a benefit to both. Cloud-based software can process large datasets more quickly than a tablet, however that processing would happen before the survey team knows if the capture is complete. To ensure a capture is done correctly while on site, teams can process and visually inspect Nexys captures in the field before returning back to the office.
Mobile scanning brings added flexibility to surveying and mapping, but choosing the right payload can impact just how much speed and accuracy it brings to your current workflow.
That's why Nexys was designed from the ground up to be modular and flexible, meaning it can be used as a handheld mobile scanner, mounted onto a backpack or a vehicle, or attached to a compatible drone with an Autonomy License to enable fully autonomous GPS-denied flights.
One Nexys unit gives you multiple scanning options so you can capture accurate data in any environment in the fastest and safest way possible while maintaining global accuracy.
The Nexys mobile mapping and autonomy payload is a complete solution that offers unique and innovative modularity for 3D spatial mapping applications that helps maximize flexibility and reduce costs.
Reserve your personalized demo today to see the modular Nexys autonomy and mapping ecosystem for yourself.
