CC Jan-Feb 2022

CASEstudy
Rapid 3D scans
Trimble laser scanning technology delivers high-precision surveys for a historic church restoration
In 2021 a team of geospatial mapping
specialists visited the 900-year-old
Newcastle Cathedral Church of St
Nicholas. The company, Gridmark
Survey, was there to use a new state-ofthe-art
3D laser scanning technology in
the restoration of the cathedral. They
would assist Historic Property Restoration
and Classic Masonry with site
engineering. Gridmark would provide
dimensional marking of the groundworks
and paving to the new outdoor terrace in
the Cathedral churchyard.
The firm was using the new Trimble X7
laser scanning system, a high-precision,
rapid-fast modern laser scanner, which
captures millimeter-accurate reality data.
Gridmark collaborated with KOREC
Group, the UK Trimble distributor who
provided the technology. The Trimble X7
3D laser scanner is integrated with
Trimble's Perspective software and
specifically designed for in-field control
and registration.
"We knew we could revolutionise how
the stonework was inspected and
measured and show that we could speed
up the process by more accurately
measuring the masonry without
scaffolding and additional labor," said
Christopher Mooney, managing director
and senior surveyor with Gridmark
Survey. Safety was also important to
Gridmark but the X7's remote sensing
capability eliminated the need for safety
training, saving valuable worker time.
The scanning team consisted of two
surveyors on site for three days. During that
time, they captured details of the building's
14th-century interior. "We collected 104
laser scans and 3.7 billion measurable
points," Mooney said. "There were three or
four rooms not accessible, or it would have
been 110 scans and 4 billion points."
In some places, pollution had eaten
away much of the stonework. With the X7
they could zoom in on an area and
provide details of the damage
immediately. "One window was extremely
deteriorated on the outside but beautiful
inside so you could see how it was
supposed to look," Mooney said. "That
level of detail captured by the scanner
was phenomenal.
"It would take a stonemason six weeks
to inspect and measure what we
scanned in three days with the Trimble X7
scanner," Mooney added.
Gridmark also had access to the
Cathedral's Lantern Tower, a climb of 162
steps. They set up the scanner and
captured 360-degree scans from the
tower, the roof and the adjacent buildings.
Each time they moved to a new position,
the X7 automatically leveled and
calibrated itself and the Perspective
software automatically registered each
scan, allowing them to review everything
in 3D before moving on.
Once the scanning was complete,
Gridmark imported the data into Trimble
RealWorks® software to create a 3D
capacity for making a point cloud as well
as a scaled digital model of the
Cathedral. Creating a 3D representation
of the Cathedral ensured that the detail
and design was preserved forever.
"The scanner is so quick. The user
interface is very intuitive, and we like the
high-sensitivity mode that allows us to
capture difficult surfaces. We also like the
ability to flip between different scans to
see more detail," added Mooney.
"We were blown away by the data we
downloaded at the end of the day," he
noted. "Trimble RealWorks has the
capability to make point clouds look very
much like real life. We ended up with
data so rich it was hard to know what to
choose to share with the client. What
was most important, though, was that we
had absolute confidence in the results.
We knew that 900 years of heritage had
been safeguarded."
www.Trimble.com
34
January/February 2022