Download Uses in Building and Architectural Surveys Article

HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
Uses in
Building and Architectural Surveys
Geoff Jacobs
complete geometry to be captured even
when people move through the scanner’s
field-of-view.
Trends
Laser scanning technology is being
increasingly used for building and architectural-related surveys. The two main
reasons are decreasing costs and better
informed clients.
Scanning of buildings is becoming
increasingly mainstream.
Image courtesy: D. Woolley Assoc. & INOVx
T
he use of high-definition surveying/laser scanning for various
types of building and architectural surveys is becoming more
mainstream everyday. This article takes
a closer look at the specific applications
and benefits that this technology brings
to these types of projects.
Scan of interior room captured using
ultra-fast phase-based scanner.
Image courtesy: D. Woolley Assoc. & INOVx
Lower Cost Services
Costs have declined sharply both in
the field and the office. Field costs have
been driven down on two separate
fronts. First, new full vertical and full
horizontal field-of-view scanners sharply reduce the number of time-consuming
scanner setups and target placements.
The second driver behind reduced field
costs is the fairly recent commercial
availability of ultra-high speed “phasebased” scanners. Although these ultrafast scanners are short range, they are
well-suited to many interior areas.
Office costs have also decreased significantly. This is credited to advances in
CAD-friendly software/workflows, along
with more features that automate processing point clouds into final deliverables, often 2D plan and elevation drawings. The ability to “slice” point clouds
and quickly create 2D plan and elevation
drawings from these narrow slices directly within popular CAD applications
Processing
scan data
directly
within CAD
can reduce
office costs.
Image
courtesy:
The
Mollenhauer
Group
A Natural Fit
Building and architectural projects are
generally considered a natural fit for laser
scanning. Many building features are vertical or directly overhead, which provides
good line-of-sight and a good angle of incidence for a scanner’s beam. Scanners
can capture surfaces and points that are
otherwise hard to reach or that may not
be safe to walk on. Another fit: many architectural and building projects feature
complex geometry that is well-suited to
high-definition surveys. Lastly, buildings
are intended to be occupied and a laser
scanner’s dense data capture enables
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED
HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
was a major time savings breakthrough
when it was introduced several years
ago. Prior to that, 3D models had to be
created in order to derive 2D drawings.
Now, 2D drawings can be directly extracted from point clouds in AutoCAD or
MicroStation using highly affordable
point cloud CAD-integration software.
Better Informed Clients
A second factor behind the growing
use of high-definition surveys for architectural as-builts is that more and more
clients are becoming aware of the benefits of the technology. Some are requiring it. This is a direct result of the rapidly growing number of building surveys
successfully performed every day with
scanning. Clients have learned that
high-definition surveys offer cost advantages for certain types of projects.
They’ve also learned that even at an
equal cost, scanning provides several
added-value benefits. These include
faster project turnaround, improved
safety, and more complete and accurate
survey data that can be re-visited without re-visiting the building itself. Faster
turnaround is often a compelling benefit
for owners of commercial properties
who are eager to put the property back
into commercial use. In this case, every
day of delay can represent tens of thousands of dollars or more in lost revenue
for the owner.
Existing Buildings and
New Construction
Based on my observations since the
technology’s commercial inception in
early 1998, the successful application of
high-definition surveying for new building construction QA (Quality Assurance)
has been one of the best kept secrets in
the business. Many people think of a
scanner for capturing “scenes.” They
don’t typically think of using it for capturing selected single points that are a
common part of construction QA for a
new building. However, the right type of
scanner can be cost-effectively used (via
localized “fine scans” of objects) to accurately extract single point coordinates
of corners, edges, bolt patterns, etc. The
laser scanner, its accessories, and its
Scans of 22-story building were used for construction QA and window frame as-builts.
Image courtesy: Mabat
companion software must allow highaccuracy deliverables (e.g., 1/4" or better) of corners, small attachment clips,
etc., at ranges up to 165' or more. Very
fine scanning capability (e.g., 1/16" grid
spacing) and small spot size (~1/4") at
these longer ranges are “musts” for
these applications.
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
One reason that laser scanning does
well in new building construction is that
during the early stages of construction,
a laser scanner often has good line-ofsight to much of the structure from many
vantage points. Another reason is that in
a building’s early stage of construction,
it’s not always easy to get physical
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED
HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
Scanning has been used on many stadium projects. Image courtesy: Jacob & Hefner
access to all parts of it, so remote measurement is very handy.
Fifty percent of scanning is done on
existing buildings. However, even
though most (in terms of the number of
scanning surveys) are done on existing
buildings, there is still a lot of scanning
being done on brand new construction.
The scenarios that most lend themselves to scanning are larger, complex
exteriors; large open floors; vaulted or
domed ceilings; open interstitial utility
spaces above false ceilings; complex
roof support structures; and multi-story
structures. Small rooms with a lot of furniture are typically not good candidates,
as the scanner’s line-of-site can be obstructed too often and geometry can
otherwise be easily collected by hand.
Specific Applications
Laser scanning is used in many types
of survey applications related to buildings:
High-definition surveys are well-suited to
capturing roof support structures.
Image courtesy: Ming Surveys
data capture capability eliminates the
need to use man-lifts or other means to
physically reach the object(s) of interest.
Construction QA—common for critical geometry, such as steel column verticality, base plate locations, tie points, elevation consistency of concrete forms,
new concrete pours, etc. As one construction manager who took advantage
of laser scanning for QA of a downtown
office building told me many years ago,
“It’s a lot better to do effective survey
QA during construction than to have
some guy up on the 22nd floor with a
welding torch after the project is supposed to be done.”
Fabrication QA—the geometry of
some large, special parts of modern
buildings can be quite complex. Laser
scanning is used to QA these parts while
they are still at the fabrication shop.
Final as-builts—final as-built drawings are part of many construction contracts. When I’ve talked to people in the
industry, I’ve been told that this is often
not done properly and in some cases it’s
not done at all. The historical reason for
this is that it’s either too hard or too
Building modifications, renovations,
expansions—this is the most common
application. It often involves old, heritage buildings where there’s a keen desire to accurately preserve elements of
the existing building. New designs must
be done around these key elements. The
accuracy and completeness of a
high-definition survey is well-suited for this scenario. Some of these
projects are quite large in scope
and some service providers who
have specialized in this area have
fared very well. This activity is
more prominent in Europe and Asia
than in the U.S., but it’s becoming
increasingly common here, too.
Property/ALTA surveys—Highdefinition surveying is used on
buildings where elements of the
building itself need to be surveyed
for possible encroachments with adjacent properties. One common
case is a “zero set-back” scenario in
which the walls of the building form
the property boundary. Scanning
can be used to precisely derive
building corners, without having to
deal with prism pole offsets to the
exact corner. A second common scenario is where a building may have
some structures, such as transformer boxes, fire escapes, and air
conditioning units, which extend
horizontally from the sides of the Laser scanning was used for an ALTA survey of this
building. Laser scanning’s remote building. Image courtesy: Cullinan Engineering
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED
HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
rigorous field procedures allow laser
scanning to be successfully used in this
application, as the required accuracy for
these measurements is typically at the
edge of the best scanners’ capabilities.
Window casing geometry for window fabrication—some windows are
fabricated after the casings are built on
site as part of the building structure.
Laser scanning has been used cost effectively for this.
Redevelopment proposals—Highdefinition surveys are used to capture existing buildings or even city blocks for the
purpose of creating compelling marketing proposals for developer clients. For a
relatively low cost, the registered point
clouds can be used with point cloud software to create an animated fly-through of
the existing site. Advanced users add proposed designs directly into the point
clouds, creating exciting proposals to differentiate their organization’s proposal
from competing proposals.
High-definition surveys are often used for theme park structures.
Image courtesy: JMR Surveying
costly to do it right and the owner doesn’t
press the case. Laser scanning is changing that scenario.
Construction engineering—during
many projects, temporary structures are
often designed and built to aid in the
construction activity itself. For example,
special scaffolding or sheet piles may
need to be designed and built. Scanning
can provide quick, accurate as-built input for construction engineering needs.
Construction planning and scheduling—making modifications to existing
Scanning is used for surveying cladding
substructure attachment points.
Image courtesy: Mabat
buildings can pose challenging problems. There may be constraints as to
where cranes can be placed, scaffolding
can be erected, or paths through which
existing elements can be removed or
new elements brought in for installation.
Scanning can quickly provide accurate
complete as-built information for construction planning.
Attachment point locations for fabricating cladding sub-structures—building claddings, such as glass outer walls
or pre-fabricated concrete facades, are
often attached to inner structural members via special clips or other specific attachment points. Sub-structures connect a modern building’s structure with
its outer cladding structure. These substructures are often fabricated after the
building’s steel structure is erected, attachment clips have been installed, and
the 3D locations of the attachment clips
have been measured precisely. This
measurement task has historically been
done with traditional survey equipment
and man-lifts. Over the last few years,
however, laser scanning has started to
replace these traditional methods. Only
the most accurate laser scanners and
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
Scan with true-color overlay of building for
Los Angeles re-development project.
Image courtesy: The Mollenhauer Group
Heritage archive—in virtually every
country there is a government organization dedicated to cultural heritage and
recordation of heritage buildings. In the
U.S. this is HABS. In the UK, it’s English
Heritage, and so forth. In addition, various charitable foundations, universities,
and philanthropists contribute funds to
such efforts. Generally laser scanning is
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED
HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
Slicing through point
clouds is an effective
way to create 2D
drawings.
used in conjunction with other methods
of recordation, including high-resolution photography, and visual inspection
of the building’s materials. Full sets of
2D plan and elevation drawings are often required and the scan data itself is
increasingly provided as part of the
client deliverable.
Heritage re-building—High-definition
surveys are also used to precisely capture
existing geometry for heritage buildings
that are to be meticulously taken down
and then re-built in another location.
Scanning is a great tool for brick-for-brick,
panel-for-panel matching of the original
building with the re-built building.
Problem analysis—scanning is used
to help analyze structural damage or
even cosmetic damage, such as older
buildings that have begun to shift and
sag over time. Where there has been a
collapse or other serious damage, scanning is used to accurately assess the
structural damage so as to enable accurate repairs. A corollary of this application
is to use scanning to capture an accurate
“before” geometric snapshot of a building prior to any construction being completed on the building. In this way, if a
building is or is not damaged during construction, the contractor or building owner will have a record that can be used to
quickly resolve disputes such as, “Hey,
that exterior crack wasn’t there before!”
or “I think you altered the shape of my
building when you installed the underground garage!” Scanning provides inexpensive dispute resolution insurance.
Monitoring deformation and building movement—scanning is being used
to monitor deformation of specific building structures and possible movement
of entire building caused by excavations
adjacent to the building, settlement due
to poor soil conditions, or faulty design.
economic reasons. Laser scanning is
used for capturing detailed building
outlines and facades and for capturing
heritage blocks that are candidates for
downtown redevelopment.
3D GIS—One of the first implementations of this has been in Europe where
popular landmarks are being captured
by high-definition surveys and then
modeled for addition to vehicle navigation maps. Instead of a flat symbol on a
2D map, the driver can see what a landmark looks like from the road in a 3D
view as he/she approaches it.
Entertainment and film—Buildings
are scanned and a digital model is created from the scans. The model is then
used to assist the addition of special
computer graphics (CG) effects into a
scene with the building. A good example
of this was the scan of a church interior
Miscellaneous Applications
In addition to the above, there are several emerging and specialty applications.
Homeland security—High-definition surveys are used to create accurate 3D models of buildings to aid authorities and building owners in helping to prevent and respond to possible
terrorist actions.
Emergency Services aid—3D building models are starting to be used by
emergency services providers for determining best access for fire fighting services, for example.
City planning—Accurate models of
existing cities aid planners in visualizing
modifications to downtown skylines. Office space with a good view fetches
much higher tax revenues, so city planners use these models for practical
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
Scanning was used to model a church
interior for the movie End of Days.
2D elevation
drawing created
from laser
scan data.
Image courtesy:
Plowman Craven
Associates
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED
HIGH-DEFINITION SURVEYING: 3D LASER SCANNING
for Arnold Schwarzenegger’s last feature
film, End of Days. A devil pops through
the floor of the church and wreaks havoc
with the interior of the church, thanks to
scanning and CG. (Fortunately, Arnold
was victorious over the devil and was
later able to run for Governor of California). Another movie use is to scan a oneor two-story building which allows computer graphic artists to accurately add
more stories to make it look like it is, for
example, six stories high. High-definition surveying adds value by capturing a
building’s physical flaws, which make
the multi-story replica look more realistic. This technique was used, for example, to create multi-story buildings for
the feature film, Moulin Rouge.
Opportunities and Challenges
Although the use of scanning for building and architectural applications is a natural fit and many such projects are done
every day, there is one caveat. Since the
technology’s inception, I’ve followed
many users who have either focused on
this area or provided some services for
these applications. I’ve learned that not
all are commercially successful.
Many 1-day building surveys are toward the lower end of the surveying
services price chain. Architects are notoriously thrifty and some choose to do
these surveys on their own either manually or with a handheld EDM. Others
quickly opt for the lowest price bid with
no regard to added value. As a result,
service providers who offer architectural scanning services may find that they
need to price their services lower than
what they’d like in order to get the business. To be sure, many service providers with scanning capabilities have
landed significant projects with excellent returns, but this is not a given. Typically the organizations that are successfully landing large projects already
have a business in this area and are
adding scanning to the mix as an
added-value service.
DISPLAYED WITH PERMISSION • PROFESSIONAL SURVEYOR MAGAZINE • June 2005•
Summary
Architectural and building surveys
are a natural fit for high-definition surveying. Uses today are common for both
new construction and existing buildings.
The use of scanning is growing in this
area thanks to steadily declining services costs and better informed clients. Although this area has historically not
been quite as lucrative as the civil, infrastructure, industrial plant, and facilities
applications, there are numerous successful projects and service providers in
this space today.
Geoff Jacobs has been
employed by Leica Geosystems, HDS, Inc.
since 1998. He currently
acts as Senior Vice
President, Strategic
Marketing. He is also a
contributing writer for
the magazine.
WWW.PROFSURV.COM
• ALL RIGHTS RESERVED