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understanding lidar 849

To add additional configuration to the time-versus-detail equation, a phase-shift scanner,
set at its highest resolution, will still likely be faster than a time-of-flight scanner set at a lower
resolution. The trade-off is that the phase-based scanner will require more setups to collect the
area because of the limited range. We will discuss this in more detail later in this chapter.
Another benefit of LiDAR is data collection speed. Although almost unfair, it is still
necessary to compare LiDAR to traditional survey methodology on the basis of the speed of
data collection. A scanner can collect data thousands of times faster than traditional survey
equipment and can provide a true-to-scale, three-dimensional representation of the existing
conditions of the project area. It is true that if all the project requires is four corners of a building
or room, then using a scanner is like using a sledgehammer for fine woodworking. However, if
you are trying to understand a cluttered pipe gallery inside a pump room, then LiDAR is by far
the better tool. It should never be said that LiDAR is a silver bullet or that it should be used on
every job. We have personally been involved with projects that either utilized the wrong type of
scanner or were not good candidates for LiDAR, and they resulted in negative outcomes.

Know Your Scanner
There is no firm rule on what type of scanner you should use in a given condition. When used suc-
cessfully, lidar can be very fast and accurate and provide a lot of value. as an example, on one
project we incorporated a color lidar scan for a 250,000 sq ft interior space for a client who needed
to keep a facility operational for 20 hours per day. We were able to work with a scanning provider to
scan only between 1 a.m. and 4 a.m., and they were able to scan all 250,000 sq ft in the course of
a single week! That is a lot of area to cover quickly.
While that is an example of a very successful scan, scanning can also just as easily fail if it is not
executed properly. one place where you will need to exercise caution is when scanning historic
structures. The level of detail you specify will need to be higher to take into account building ele-
ments like intricate stonework or reliefs. We have seen scans become so detailed that the files are
nearly unusable because they have so many points. But if a scan is not dense enough, it will not
capture the required detail. if it’s the first time you’re specifying a lidar scan, make sure to ask
the advice of someone experienced in the technology.

As with most projects, safety is of paramount importance. This is one aspect of LiDAR
that can be easily overlooked. LiDAR gives you the ability to measure objects without having
to physically touch them, such as things that are out of reach, in a hazardous area, or in a
confined space. In certain conditions or spaces, LiDAR can add a level of safety that is otherwise
nonexistent. For example, with LiDAR you can measure electrical equipment that is not safe to
touch, or you can collect information above a drop ceiling or in other confined areas. You can
also collect information in busy and congested areas without needing to enter those areas—for
example, a building that is under construction or a building that might be structurally failing
and is not safe to enter.
When used correctly, a LiDAR scanner is accurate and can collect information about building
features to within millimeters of its actual position. It is not because LiDAR is more accurate

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