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848 | ChAPteR 21 Working With Point Clouds

Selecting the hardware
Not all LiDAR scanners are created equal, and it is important to keep in mind the project
requirements to apply the right scanner to the project. A successful project relies on deploying
the correct technology, and using the wrong scanner will put the project at risk of not meeting
scope, schedules, and budgets. Following are some basic rules of thumb for using or procuring
LiDAR for a project.
First, it’s important to understand the scanner itself. There are two types of scanners: a time-
of-flight scanner and a phase-shift scanner.
The time-of-flight scanner measures the time it takes for the emitted laser pulse to be
returned to the scanner. This type of scanner has the following characteristics:
◆ ◆ Slower collection rate: 50,000 points per second

◆ ◆ Longer range: up to 1,000ʹ or 300 m
◆ ◆ Lower resolution
◆ ◆ Smaller data file sizes
◆ ◆ Most effective in exterior applications, such as site collection, exterior building conditions,
and especially for tall buildings
The other scanner type, a phase-shift scanner, measures the phase shift of the emitted laser
compared to the light it receives when the pulse is bounced back to the scanner from the target.
This type of scanner has the following characteristics:

◆ ◆ Fast collection rate: 1,000,000 points per second
◆ ◆ Shorter range: up to 65ʹ or 20 m
◆ ◆ Higher resolution
◆ ◆ Larger data file sizes
◆ ◆ Most effective in short-range applications such as interior spaces and confined spaces
◆ ◆ Can require more setups (or scan points) because of the range limitations

Benefitting from LiDAR
Now that you have a better understanding of LiDAR as a technology, we can begin to discuss
the benefits of using LiDAR and how to deploy it on your project. The benefits are simple to
understand, but they cannot be overstated. The first benefit is the level of detail that can be
achieved with a scanner. A significant amount of detail can be collected with a LiDAR scan.
There is a trade-off to this benefit, however, in the direct correlation between the level of detail,
or resolution achieved, and the time that it takes to collect the data. Most scanners have the
ability to change the scan resolution in the field. If the project focus is an interior space with a
high level of detail, then it may be desirable to set the scanner to a higher resolution—similar
to what you would do with a digital camera. If the project is of a broader scale, say to locate the
exterior footprint of a building, then a lower resolution will suffice, allowing you to expedite
the scan time.

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