Construction assessment with a laser range finder is
a kind of non-intrusive data retrieval technology [7].
Cases have demonstrated that a laser scanner is a
useful tool in either accessing data in a construction
site or measuring data for interior billing of materials
[2,4,5]. A scanner seems to be feasible to record
ground profile in a large construction site with a
demand for accuracy less than one centimeter, or for
cost estimations of interior renovation. Being able to
conduct scans in a large area and to inspect the
dimensions of a small region at the same time extends
a long-range laser scanner’s functionality to take
advantage of both types of measurements and displays.
Combining laser ranging with commercial design
software can model existing facilities four times faster
than photogrammetry [1]. The range finder, which uses
laser beams to locate the position of a surface point,
has been used in construction for a long time. Recent
developments in technology have enabled the tool to
cover a large area for the continuous recording of a
surface configuration. For example, rapid local area
sensing and 3D modeling was applied for better
planning and control of construction equipment
operation [6].
http://www.aleeshainstitute.com/interior-designing-course.php
This study tries to built-up a monitor procedure
during the construction process. Instead of traditional
discrete and point-based data survey, this study applied
a long-range 3D laser scanner (Fig. 1) as a survey
device for continuous data retrieval. It can reach 100 m
and generate a 999x999 laser dots at about 4 mm
interval in 17 minutes. The distribution of dots is
considered as a continuous sampling of x-, y-, zcoordinate of a particular component. Scans are
conducted automatically. The sample points can be
easily added up to millions. The initial cost of a 3D
long-range laser scanner is about $100000 USD, which
is much higher than traditional tools do.
Projection efficiency has also increased. If each
point takes a total station about five seconds to aim, a
laser scanner that projects 999*999 points in 999
seconds would be 4,995 times faster for the same
amount of laser points. The resolution of a view can be
increased by tiling scans with the highest resolution
each from left to right and from top to bottom. Once a
scan is done, its corresponding computer format is
stored as the point cloud model. The cloud format can
then be wrapped or transferred into a polygonal model.
4. Interior renovation
Based on the definition of local Building
Technology Regulations, interior renovation specifies
the works for space rearrangement, circulation, and the
allocation of materials without original building usages
being changed. Renovation usually includes design,
construction, and finishing stages. Upon to the client’s
request, the design process starts from site survey,
planning, space layout, detail design, defining
specification, to construction preparation. A
construction firm will be hired based on the design
specifications under clearly defined contract and
schedule to make sure the whole works are completed
correctly and timely.
The test case is a campus building interior
renovation job located in the Department of
Architecture, NTUST. The floor area is shown in
Appendix. Real construction took about 13 days to
complete.
5. 3D scan process
In addition to represent the as-built space data in
3D form, scan data have to be integrated with design
data. So the scan procedure has to combine design
inspection to create a new working process. Scan
works are divided into stages, such as planning, on-site
jobs, data editing, and publishing.
1. planning stage:
z Define scan region: based on the
description of working drawings, scan
targets, and spaces to define scan scope;
z Scan planning: identifying objects and their
locations for possible scan obstructions and
best scan locations;
z Schedule: planning scans with construction
progress to avoid interference and to
retrieve the most updated data in time.
2. scan stage: the on-site jobs including preparation,
execution, and edit of scan data (Tab. 1).
3. scan data editing:
z cloud registration: Clouds are registered to
show the dimensions of spaces as a whole.
z cloud editing: Remove noise from each
point cloud and slice it for profiles export.
z CAD system integration: Export edited
clouds to AutoCAD, a popular drafting
platform, and merge with 2D vector
drawings.
4. scan data publishing: Publish cloud data on web
pages based on Octree format and AutoCAD
DWF format. The former format enables large
point cloud file being browsed and measured in
full scale over Internet.
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