The document describes the use of lidar to analyze a bridge located on the Sheng Li road at Kuang Fu campus. Field measurements found the front side of the bridge ladder to be approximately 0.9 meters wide and 8.18 meters long, while the back side was 0.9 meters wide and 9.16 meters long. Lidar data was collected from 3 stations and produced a point cloud that closely matched the field measurements. The lidar data provided a detailed 3D representation of the bridge and was useful for determining its size, shape, and reconstructing its geometry, demonstrating lidar's applicability for infrastructure assessment.

1. Muhammad Irsyadi Firdaus
P66067055
LASER REMOTE SENSING 1
Reason for choosing your scene/object
I choose a bridge as my object review. The reason I choose the bridge for my research object
because the bridge is unique and I want to know the length and width of the bridge. Besides, I
would like to know the geometry shape of the bridge.
Detailed description of your scene/object
The bridge is a structure built to span physical obstacles without closing the way underneath
such as a body of water, valley, or road, for the purpose of providing passage over the obstacle.
The bridge was made to cross the obstacles of the river, irrigation, ravine, sea, lake, valley and
road.
The location of my research object is on the Sheng Li road, Kuang Fu campus. Our group took
data on Thursday, April 13 2017, at 02.00 PM. As for the object I studied is the bridge. The field
measurements obtained the width of the bridge ladder approximately 0.9 meters and a long ladder
approximately 8.18 meters for the front side. While the length of the bridge ladder behind the wall
is approximately 9.16 meters and has a width of about 0.9 meters.
Figure 1. The back of the object (left), Shape of the ladder (Middle),
The front of the object (right)
Detailed description of my lidar data
Lidar data obtained from 3 stations that can cover all areas to be studied. Once the object of
the bridge is scanned, the result looks very good. The location of the station will be shown below.
Figure 2. Point of view at the first station (left), Point of view at the second station (middle),
Point of view at the third station (right)
The difference of bridge measurement result from field measurement with TLS data
measurement is very small. For measurement of stair width from TLS data is 0,9 meters and the
length of the bridge ladder is 8.20 meters. As for the back side has a width from TLS data is 0.9
meters and the length of the ladder is 9,17 meter. So the length of the bridge ladder on the back

2. Muhammad Irsyadi Firdaus
P66067055
LASER REMOTE SENSING 2
side is longer than the front side, difference length of the bridge ladder from both sides is 0.97
meters.
Figure 3. (a) The long ladder bridge
from the back side, (b) The width of
the bridge ladder from the front side.
How does the lidar data represent my scene/object
The quality of point cloud data from TLS is great for describing the object of the bridge so it
can display the bridge object in three dimensions. In Figure 3a looks a form of bridge made from
iron and cylinder-shaped that is very unique and has a good architecture.
Figure 4. The bridge from the upper side
The Upper side of bridge has a bigger width, it has a very nice design (Figure 4). TLS data
can present objects in the field although there are some parts of the bridge that have a low density
of points cloud. That's because the object is closed by something like leaves, trees and others
influenced by the location of the TLS station. As in this case, in figure 3b the left side looks not
too detailed because the position of TLS is to the right of the bridge that is in the first TLS station.
So, that image has a low point cloud density. To get better visualization, the object should be
scanned in whole object and detail the three-dimension images are displayed.
a
b

3. Muhammad Irsyadi Firdaus
P66067055
LASER REMOTE SENSING 3
Is lidar useful for my purpose?
Lidar is very useful for this case. Lidar can determine the size of an object and can display a
three-dimensional shape of the object. The existence of lidar data can reconstruct an object such
as a bridge. Many authors have proposed semi-automatic or automatic methods to allow
application of laser scan data for several fields of engineering. Used terrestrial laser scanning as a
method to collect data for automatic crack detection in building facades. Laser scanning have
proved useful for detailed geometric documentation of bridges, but also to provide suitable models
for subsequent structural analysis.
Reference
J. Valença, I. Puente, E. Júlio, 2017, Assessment of cracks on concrete bridges using image
processing supported by laser scanning survey, Journal Construction and Building
Materials, Page 668-678, Vol. 146
B. Riveiro, M.J. DeJong, B. Conde, 2016, Automated processing of large point clouds for
structural health monitoring of masonry arch bridges, Journal Automation in
Construction, Page 258-268, Vol. 72