Human Body Modelling by Development of the Automatic Landmarking Algorithm

48 Pages·2012·2.49 MB·English

by  Big Muscle

University of West Bohemia
Department of Computer Science and Engineering
Univerzitni 8
30614 Pilsen
Czech Republic

Human Body Modelling by Development of
the Automatic Landmarking Algorithm
The State of the Art and concept of Ph.D. Thesis
Tomáš Kohlschütter

Technical Report No. DCSE/TR-2012-11
August, 2012

Distribution: public
Technical Report No. DCSE/TR-2012-11
August 2012
Human Body Modelling by Development of
the Automatic Landmarking Algorithm
Tomáš Kohlschütter

Abstract
In this work, I describe the methodology of automatic computer-based measurement for tak-
ing anthropometric data. The result of this process can be employed in many areas, e.g. secu-
rity, medicine, sport or clothing industry. The designed methodology comes out from the de-
mand to create, from the measured person’s view, the least annoying system of the meas-
urement. It must be simple (cheap and portable) as much as possible from the operating per-
sonnel’s view. The proposed methodology comes out from the model of human body. Several
potential sources of problems are discussed and some possible solutions are proposed. Com-
plex system can be created when we solve these problems completely. This problem is cur-
rently being solved at a number of world workplaces. Efficiency of the proposed methodology
is being verified on the use case of the clothing industry.

This work was supported by UWB grant SGS-2010-028 Advanced Computer and In-
formation Systems.

Copies of this report are available on http://www.kiv.zcu.cz/publications/
or by surface mail on request sent to the following address:

University of West Bohemia in Pilsen
Department of Computer Science and Engineering
Univerzitni 8
30614 Pilsen
Czech Republic

Copyright © 2012 University of West Bohemia in Pilsen, Czech Republic
Table of Content 1

Table of Content
1 INTRODUCTION ............................................................................................................................. 2
2 STATE OF THE ART – ANTHROPOMETRY ........................................................................................ 3
2.1 DEFINITION, ORIGINS AND USES ............................................................................................................ 3
2.2 TRADITIONAL MEASUREMENTS ............................................................................................................. 5
2.3 COMPUTER-BASED MEASUREMENTS ...................................................................................................... 7
2.3.1 2D measurements ................................................................................................................. 7
2.3.2 3D measurements ............................................................................................................... 21
3 PROPOSED MEASURING SYSTEM ................................................................................................. 24
3.1 CAMERA SYSTEM ............................................................................................................................. 24
3.2 MEASURING AREA............................................................................................................................ 25
3.3 POSSIBLE DIFFICULTIES ...................................................................................................................... 27
3.4 GETTING WORLD COORDINATES .......................................................................................................... 27
3.5 OBJECT DETECTION .......................................................................................................................... 29
3.5.1 Background removal ........................................................................................................... 29
3.5.2 Object contouring ................................................................................................................ 30
4 AUTOMATIC LANDMARKS LOCALIZATION ................................................................................... 31
4.1 NEW PROPOSAL............................................................................................................................... 31
4.2 CIRCUMFERENCES COMPUTATION ....................................................................................................... 33
4.3 LANDMARKS DEFINITION ................................................................................................................... 33
4.3.1 Body height ......................................................................................................................... 34
4.3.2 Neck circumference ............................................................................................................. 34
4.3.3 Waist circumference............................................................................................................ 34
4.3.4 Chest circumference ............................................................................................................ 35
4.3.5 Hips/seat circumference ...................................................................................................... 35
5 EXPERIMENTS .............................................................................................................................. 36
5.1 SOFTWARE SOLUTION OF THE PROPOSED SYSTEM ................................................................................... 36
5.2 CALIBRATION ERROR ......................................................................................................................... 36
5.3 RESULTS OF EXPERIMENTS ................................................................................................................. 37
6 FUTURE WORK ............................................................................................................................. 40
REFERENCES ................................................................................................................................... 42
APPENDIX ....................................................................................................................................... 44
MEASURED PERSON #2 .......................................................................................................................... 44
MEASURED PERSON #3 .......................................................................................................................... 45
MEASURED PERSON #5 .......................................................................................................................... 46
Introduction 2

1 Introduction
My work concerns how to fulfil the requirement of the anthropometry da-
ta acquisition. It comes out from the demand to measure hundreds of people in
their everyday clothes for several reasons. This can be utilized in wide areas of
the security, medicine, sport or clothing industry. The traditional method of tak-
ing human dimensions using a measuring tape can be not only very time-
consuming but sometimes impossible or unsuitable. Thus, there is a need to
create a portable contactless computer-controlled workplace to speed up this
measurement process.
In the past few years, an active research on replacing traditional anthro-
pometry measurements using a measuring tape with computer-based 2D ([6],
[8], [10], [14]) or 3D techniques ([9], [14]) has been conducted. Based on litera-
ture and our basic experiments, we found that the creation of an image-based
2D anthropometric measurement system will be the best way. Performance of
such measurement was already discussed in [8]. Requirements given by the
project submitter were that the system must be portable, people cannot be re-
quired to get undressed, and the system must be very easy and fully automatic.
The objective of this work is to summarize everything needed for design-
ing a complete, fully automatic 2D anthropometric system and propose a new
technique for automatic detection of several spatial human body parts that
would be useful in the areas named above.
State of the Art – Anthropometry 3

2 State of the Art – Anthropometry
2.1 Definition, origins and uses
This part is completely overtaken from [17].
The beginning of quotation:
The word “anthropometry’’ was coined by the French naturalist Georges
Cuvier (1769–1832). It was first used by physical anthropologists in their
studies of human variability among human races and for comparison of hu-
mans to other primates. Anthropometry literally means “measurement of
man,’’ or “measurement of humans,’’ from the Greek words anthropos, a man,
and metron, a measure. Although we can measure humans in many different
ways, anthropometry focuses on the measurement of bodily features such as
body shape and body composition (“static anthropometry’’), the body’s mo-
tion and strength capabilities and use of space (“dynamic anthropometry’’).
The origins of anthropometry can be traced to the earliest humans, who
needed information about body parts for many of the same reasons which
apply today—to fit clothing, design tools and equipment, etc. No doubt they
also used body measurements for other‚ “non-design’’ purposes, such as
footprints to estimate the body size of potential adversaries. These and other
early applications called for the measurement or estimation of height, as well
as the shape and size of hands, feet, and other body parts. Such needs gave
rise to the very early use of the terms‚ “span”, “cubit”, and “canon”, which
connote extended arm width, height, and a standard, respectively.
Body proportions were of great interest during classical times, which is
clearly evident in the work of artists and sculptors of the period. Around the
year 15 BC, the Roman architect Vitruvius wrote about the potential transfer
of harmonious body proportions to the design of beautiful buildings. Howev-
er, it was the work of Renaissance artist-anatomists, including Alberti, Pierro
State of the Art – Anthropometry 4

della Francesca, Leonardo da Vinci, and especially Albrecht Durer, that ush-
ered in the scientific beginnings of anthropometry. Durer’s four-volume pub-
lication on human proportions was the first serious attempt to systematize
the study of human size and shape.
Today, anthropometric measurements are used in a remarkably wide va-
riety of scientific and technical fields, ranging from genetics and nutrition to
forensics and industrial design. Within the field of ergonomics, there are myr-
iad applications of anthropometry, primarily associated with different as-
pects of design for human use.
The goal of ergonomics is to design tools, workplaces, and environments in
such a way that humans can function most effectively — in other words, to
optimize human performance by achieving the best possible fit between the
human operator, the equipment (hardware and software), and the working
environment (physical and psychosocial). This fit is often referred to as “the
human–machine interface.’’ Anthropometry can and does play a major role in
achieving this goal because variations in bodily features, such as shape, size,
strength and reach, affect the way people perform tasks and, thus, have an
important influence on whether the human–machine interface is a good one.
The breadth of possible applications of anthropometry for improving the
human interface is remarkably wide-ranging, from industrial equipment,
clothing and furniture, to surgical tools, farm implements, aircraft controls,
and virtually every item in the environment with which humans interact.
Over the years, engineers, designers, architects and others who design
products or processes have increasingly recognized the need for anthropo-
metric data on the users of their creations. Of course, the need for anthropo-
metric information and the type of data required varies greatly from one ap-
plication to the other. In some areas, the fit is “soft,’’ as in a loose garment
such as a bathrobe; in other areas, the fit is “hard,’’ for example, in a respira-
tor for protection against breathing toxic fumes. The fit of the bathrobe can
be an approximation and still serve its intended purpose, whereas the respi-
State of the Art – Anthropometry 5

rator mask must conform closely to the geometry of the face in order to
maintain adequate contact and prevent leakage. In the case of the bathrobe,
data on height and a few body girth measurements for the prospective user
population may be all the information needed to ensure adequate body cov-
erage for a good interface. However, for the respirator mask, it may be neces-
sary to obtain detailed three-dimensional measurements of individual facial
geometry to ensure a satisfactory fit.
The end of quotation.
2.2 Traditional measurements
Traditional anthropometric measurements are performed by experienced
anthropometrists using some instruments, mostly a measuring tape which is
intended for measuring circumferences and curvatures. Most measurements
taken on the subjects are taken in position of standing. However, a few
measures need to be taken in different positions.
Although anthropometrists should be trained, they are the most common
source of measurement error. It includes imprecision in landmark location, sub-
ject positioning, and instrument applications [9]. A landmark is an anatomical
structure used as a point of orientation in locating other structures [18]. More
informally, it can be specified as a particular point on human body which can be
used to identify a particular body part. Landmarks identification is the key ele-
ments in the collection of anthropometric data, because it is important to know
where to locate and how to align the measuring tape.
State of the Art – Anthropometry 6

Figure 1. Body measurements defined in [1].
State of the Art – Anthropometry 7

2.3 Computer-based measurements
In the past few years, there has been an active development of methods
which would replace traditional measurements by a computer system. It is in-
tended to provide more accurate human dimensions in a few seconds.
Computer-based measurements can be divided into two types – 2D meas-
urements where only two-dimensional image of the person is taken (mostly by
a digital camera), and 3D measurements where complete person’s body is
scanned and exact model is created. Description of existing measurement sys-
tems, their studies, advantages and disadvantages is discussed in following sec-
tions.
Automatic computer methods bring two main areas where all work must
be focused. The first one is the technique how information about the person to
be measured is transmitted to the computer. The purpose is to convert the ob-
ject of the real world to the digital form in order to all measurements could be
performed on it using the computer (and real object would not be needed any
more). When this is managed, the complete semi-automatic system can be cre-
ated. However, it still requires user cooperation to define where to the individu-
al measures take from. To create fully automatic system, any need of user coop-
eration should be removed and all required measures must be taken automati-
cally. This requires development of a proper landmarking algorithm. It is in-
tended to find one or more concrete points which are helpful to localize certain
body part to be measured.
2.3.1 2D measurements
One of the possible computer-based methodologies of human dimension
measurements is based on image processing. One or more pictures of the per-
son are taken by one or more cameras. The requested dimensions are computed
from these pictures. This requires the camera to be perfectly calibrated so the
image coordinates (in pixels) can be successfully transformed to the world co-
ordinates (in millimetres or whatever unit required). When photo(s) is/are tak-
State of the Art – Anthropometry 8

en, the captured object needs to be extracted from it. In other words, it needs to
be differentiated between background and person to be measured. The result of
the extraction is the person’s silhouette. For planar dimensions, distances (it
does not necessarily have to be the minimum distance) between two points on
the silhouette are just converted from pixels to millimetres. For spatial dimen-
sions, human body model needs to be created to approximate circumferences. It
is very often performed by taking person’s image from different views (e.g.
frontal and lateral) to have more measurements for modelling. Several studies
on the 2D anthropometric measurements have already been performed.
The performance of a 2D image-based anthropometric measurement was
tested in [8] to verify the accuracy and precision of the measurements. Their
system consists of two (frontal and lateral) Kodak DC120 colour digital cameras
with resolution 1280×960 pixels covering a blue backdrop that is approximately
2.5 × 1.8 metres and embedded with calibration markers. This corresponds to
resolution slightly below 2.0 mm/pixel. Therefore, it is assumed that direct
measurements will fluctuate within ±2 mm and circumferential measurements
will fluctuate within ±6 mm of the true value (by assuming a cylindrical object).

Figure 2. Plan-view of image capture set-up as introduced in [8].
The calibration of the cameras is performed using an algorithm developed
by Tsai. They take simultaneous pictures of person’s front and side views. They
analysed 349 subjects (95 females and 254 males) and the results were com-