The Pros and Cons of LiDAR
LiDAR (light detection and ranging) is a system of data collection that uses laser pulses and time-of-flight calculations to capture massive quantities of data with incredible accuracy.
We purchased a Riegl scanner nearly two decades ago to safely map limited access crossings and difficult-to-access poles. The time-of-flight scanner had an 80-degree by 340-degree panoramic field of view, and it captured 6,500 data points per second.
This incredible contraption used a system of spinning mirrors to send out 20,000 laser pulses each second. Using specialized point cloud algorithms, we could automatically merge multiple scans into one seamless point cloud. Below is a false image rendered by showing each laser return as a pixel, with the colors representing distance from the unit.
Since 2000, LiDAR has become even more powerful and portable, but it's still not the perfect solution for every application. Here are some of the major advantages and disadvantages to using LiDAR in 2018.
1. It's safe. There's no debating that LiDAR is one of the safest data collection methods for your team. Instead of crossing a busy highway or sticking energized primary bolts, LiDAR allows you to collect your data from a safer, more distant location. Many LiDAR rigs are set up to capture data on the go, whether on an automobile, helicopter, or plane. Below is a model that uses dual line scanners and GPS to survey road and pole data at highway speeds.
2. It's fast. Good luck finding a data collection tool that can collect data points faster than a time-of-flight scanner. With data acquisition rates measured in millions of points/second, speed won't be a concern.
3. It's accurate.New LiDAR scanners can capture data up to 2500m away and have an accuracy of 5mm. If you need dense data collection with high levels of accuracy, time-of-flight is hard to beat.
1. It's expensive It would be foolish to bring a LiDAR rig into your home to measure for a new carpeting project, just like it would be foolish to send your team into a substation with a few tape measures. If you're going to drop $100,000+ on a single solution, it will have to be for the right project--one that will leverage its strengths despite the high cost.
2. A single data point may not be valid. Laser scanners present truth through high volumes of data and the robust software algorithms that analyze them. A single data return is fraught with uncertainty, and may or may not represent truth. While measuring poles, we've seen that parallax can cause computer operators to select the wrong data points to assess a specific cable height.
3. It's too much data. If you're new to the time-of-flight scene, your team is probably not adequately equipped to manipulate and process all of the data that you'll be collecting. The mountains of data your device is collecting will require massive back office processing, which is why so many companies subcontract this step to specialty firms.
What's the takeaway?
LiDAR is one of the most powerful tools on the market, and with the right back-office support, it can be well worth its hefty price tag.
Before incorporating a time-of-flight data collection system, it's important that your team has the right project and the right tools to effectively manipulate and deliver your data.
For aerial OSP collection, LiDAR isn't always the answer. If your client is looking for base of pole circumference, heights measured from true ground, or pole tag identification, it will diminish the efficiency and effectiveness of your rig, as a human will still need to physically approach each pole. However, if you are looking to capture the current state of your plant, LiDAR offers a very effective way to capture and store a snapshot in time that can be evaluated at any point in the future.
In our next article, we'll discuss the headaches of using LiDAR in the OSP industry.