UWE Bristol Engineering showcase 2015

Mykola Volodko
B.Eng – Mechanical Engineering
Project Supervisor
Melvyn Smith
3D IMAGING USED FOR DIMENTIONING OF PARCELS
Introduction
This investigation looks into the 3D dimensioning
world; many different methods of 3D visualization
will be talked about, such as: laser triangulation,
photogrammetry, and stereo vision. All methods
will be looked in detail to try to figure out which
can be used to create a machine or a device that is
affordable by most, if not all, postal services in
existence to ease the operation of the companies.
Three concepts will be suggested, all of different
practicality, one concept will be about a handheld
device that could be used with ease anywhere,
second device will be a portable overhead device
and the final concept will suggest a static over
head device that should be the most accurate but
expensive out all three concepts.
Methods
Five methods were looked into to see of they were
viable to be used to find the dimensions of
cuboidal objects initially but also doing research if
they can work with non-cuboidal objects.
Firstly, laser triangulation was considered as it is a
widely used method that can find the coordinates
of a certain points with ease. Using this method, a
handful of important points could be found of the
object and then used to re-create it as a 3D object
with its dimensions.
Then Photogrammetry was considered, this
method consists of taking a numerous amount of
pictures of the same object from different angles
to intersect the lines mathematically and calculate
the difference between the targeted points to find
the dimensions of the object of interest. Then on
the computer, it takes a flat 2-dimension image
and turns it into a 3D image with its dimensions.
Time-of-flight uses a light source to shine on the
object and then capturing the reflected light and
due to the phase shift, which gets measured; the
reflection is measured and then turned into
distance information. The light emitted usually is
either a laser or some sort of LED light that uses
infrared. An imaging sensor in adjacent to the
emitter that captures the infrared light and
converts it to an electrical current. To detect these
phase shifts, the light source transmitted come in
the form of a continuous-wave or is pulsed. The
wave is usually square since it is easier to realize
using a digital circuit.
Stereo vision is the method of stereopsis to
measure a certain length. This method is
compared usually to the way the human eyes can
perceive everyday life, two cameras are placed at a
separate distance from each other and then a
certain point of the object is targeted, the
separation will make the images to cause
measurable disparity. The cameras used can be of
any type and due to the pin-hole camera model,
the position of the point the can be computed.
Also with the position of the cameras known, the
depth of can also be deduced, giving the
information required.
The final method is structured light, The main way
this system works is the triangulation method
using single laser stripes, a CCD camera is used to
track to the laser light and a device that controls
the movement of the laser strip. A laser strip is
projected onto the object that is in front of it, and
the light reflected in shown by the CCD camera on
the screen. The image that is projected gives only
two dimensions of the shape, for example maybe
the height and width of the object.
Concepts
One of the suggested concepts is a handheld
device that would operate using laser
triangulation. Such a device does exist bit its
purpose of use is different, so for the following
project, it would have to be modified. Since it is
going to be a handheld device, the size of it will
not be huge and could be filled if needed in the
glove compartment of the vehicle.
Concept number two will be an overhead device
that operates using photogrammetry. This concept
is not handheld due to the size of the apparatus
used, so will be heavy and hard to just hold in
hands. Concept can be both used in a warehouse
or a post office, and can be found in the back of a
courier’s car/truck if required to take to a
customer’s house.
The third and final concept that will be suggested
will be an overhead device that operates using
time-of-flight and more precisely using the pulsed
wave method. This concept is purely an overhead
device that can be used in a warehouse or a postal
office, so it does lack the ability of being used on
the move.
Project summary
A research has been accomplished to see what
methods of 3-dimensional imaging exists that can be
used to find the dimensions of a cuboidal and, if
possible, of non-cuboidal objects. Five methods were
looked into and from those five methods, three were
chosen as potential concepts that can be used in a
postal office or warehouse. The three concepts exist
in three forms, handheld, portable overhead device
and finally a static overhead device. The concepts
were then discussed and allocated to the according
type of company it can be used by.
Project Objectives
• Research into methods of computer vision that
could measure dimensions of cuboidal objects.
• Categorise methods to see which can be made into
handheld, back of truck or office device, to be able
to make different concepts.
• Create 3 different concept devices: one handheld,
one that can operate from the back of a truck, and
finally from a postal office.
• See if methods can be used to measure
dimensions of non-cuboidal objects.
• If possible state best method to measure both
cuboidal and non-cuboidal objects.
Project Conclusion
Laser triangulation, photogrammetry and time-offlight
were the chosen methods to use to create
concepts for a handheld, portable overhead device
and static overhead device respectively, with the
benefits explained and why they were chosen. Also
the discussion explains what type of company could
afford what method and why it would be ideal for
them to use. The main points of consideration were
the cost of the apparatus and the maintenance cost
as well as if the yare portable and would benefit the
company to invest in.