The 11th INTERNATIONAL DAAAM SYMPOSIUM
"Intelligent Manufacturing & Automation: Man-Machine-Nature"
19-21st October 2000
3D-IMAGE PROCESSING IN THE COMPACT REVERSE ENGINEERING SYSTEM
Polozkov, Y. & Svirsky, D.
Abstract: The functional model of the irregular 3D-objects
creation is considered. The structural model of compact reverse
engineering system (CRES) is shown. The modules of this
system are given. The opportunities of formalization and
automation of complex 3D-objects creation are considered. The
mathematical model of complex objects digitizing is shown. The
problems of the software for 3D-objects computer models
creation are considered.
Key words: compact system, reverse engineering, 3D-objects
digitizing, computer 3D-model.
1. INTRODUCTION
The application of CRES allows quickly reacting to changes of
a market situation. The CRES combine curtailing in space and
time with a minimum level of functional and resource
redundancy. Such systems allow irregular objects making on
the basis of their computer models. The computer models are
formed selective by the transformation of the objects digital
models. The digital models of objects are received by digitizing
of objects, which were made earlier.
broken into layers. The step of planes gets out according to
necessary accuracy. As a result of designing the computer
model turns out. It carries full design information for physical
object manufacturing. This information will be transformed to
the program, which operates movement of the cutting tool in
the industrial module.
3. THE CRES STRUCTURAL MODEL
The 3D-objects creation functional model determines the
structural model of the CRES. The efficiency of such system is
achieved by the expense of its compactness support. The
information-input module 1, information processing and control
module 2, and industrial module 3 are included in this system
configuration (fig. 2).
2. THE CRES FUNCTIONAL MODEL
The design and prototyping of free-form or sculptured objects
often involve the use of physical models at some stages of the
design process (Kruth & Kerstens, 1997). The CRES can be
considered as the information transformation channel. The
functional model of this transformation can be presented by a
set of proceeding procedures the manufacturing object
information description (digitizing); a storage and search of the
information; computer 3D-modeling; physical object making on
the basis of computer model (Rapid Prototyping) (fig. 1):
Information storage
and search
Analogue
Digitazing
Computer
aided
design
Rapid
Prototyping
Product
Fig. 1. Form creation in CRES
The description of the geometrical form of the analogue
object consists in reception of the information by the object
measurement. The received information is transformed to the
digital form. Then it is organized in digital model. Thus the
digital model is put in conformity to real object. The digital
model of object contains a file of spatial co-ordinates of points
of a surface of researched object. The received digital models
of objects form base of the graphic data for a storage and fast
search of necessary information during computer aided design.
The development of computer models of the future
products is carried out in a mode of computer design multialternative modeling. The fragments of digital models of
objects from base of the graphic data are exposed to selective
transformations by means of computer modeling. Then the
assembly order of layers gets out. The digital model of object is
1.T
he information input module; 2.The information processing
module; 3.The industrial module; 4.The video camera; 5.A coordinate table; 6.A projector; 7.A laser cutting installation; 8.A
cutting material; 9.An assembly unit; 10.Initial (analogue)
object; 11.A cutout layer; 12.A ready object.
Fig. 2. The CRES configuration
The contact co-ordinate measuring machines are widely
used as information-input module of CAD-systems (Makachev
& Chaykin, 2000 a, b). The information about each point of
3D-object surface is receive by these machines separately. This
process is low effective. So it is offered to use video-system for
3D-objects simultaneous digitizing. The modern video systems
combine low cost with sufficient accuracy and provide high
efficiency and speed of transfer of the information in the
processing module.
The configuration of offered video system includes a video
camera, projector, rotary table and personal computer. The
projector is equipped with a slide with the image of a coordinate grid with the units, which located from each other on
equally distance. The digitizing process includes a shooting of
object, on which light strips of the slide inserted in the
horizontal located projector are imaging, by the video camera
established by angle to a horizontal plane. The 3D-stage
information is imported from the video camera to the computer.
In the computer the software organizes the information in
digital models of objects. The object digital model making
elements are the scanning object surface points co-ordinates in
the chosen spatial system of co-ordinates.
The module of information processing and control is
functional invariant of all system. The interrelation between
system making modules is carried out by it. Also in this module
the computer model is developed.
The industrial module realizes the technology of level-bylevel object manufacturing. It includes: a CO2-laser; the optical
channel; a control system, a coordinate table. The layers
parallel connection allows monolithic products making. The
method of flat elements cross connection of allows 3D-object
skeleton assembly.
4. FORMALIZATION AND AUTOMATION OF
IRREGULAR SURFACES CREATION IN CRES
The mathematical model of digitizing process of spatial objects
with the help of video system was developed (Polozkov &
Zavatsky, 1999).
R ij  A 1 ( )A 2 ( ) R x  кA 3 ( )A 4 ( )A 5 ( )Sm

, (1)

where R ij = X ij ; Yij; Zij T - vector, determining a space of a ipoint of j-level of a surface of object in spatial system of coordinates; k - factor of scaling; A1, A2, , , R x - parameters
determining a space of the project center; A3, A4, A5, , ,  parameters of orientation of system of co-ordinates concerning
of the image system of co-ordinates of object; Sm - vector
determining a space of the central projections of points of
object in spatial system of co-ordinates.
This mathematical model describes dependence between
the position of points of a 3D-scanning object surface and the
position of their central projections. It allows to transform 2Dparameters of the object video image in its 3D-parameters with
the help of the following formulas:
X ij 
X S z ij  x ij (Htgx ij  Z S )
z ij  x ij tgx ij
Zij  (H  Xij )tgxij 
Yij  YS 
d ij (H  Xij )
,
fr
Z ij  Z S
z ij
,
y ij ,
(2)
(3)
(4)
where XS, YS, ZS - co-ordinates of a forward video camera
central point in 3D-co-ordinates system; H - distance of
scanning object up to a projections centre of the projector; ij angle of a direction of the projector central ray; ij - distance a
grid j-line of a slide of a projector main optical axis; fr - focal
distance of projector.
This mathematical model allows the irregular 3D-objects
digitizing process automating. The programming is carried out
with use of known computer algebra software. The algorithm of
recalculation of numerical parameters includes operations on
formation of the list of the initial data, input of elements of
numerical parameters from the received file and direct
recording of teams of mathematical calculations which are
carried out in a matrix kind.
The received results are organized in files, which describe a
spatial configuration of the object separate parties. Synthesizing
the given files on boundary points, we receive volumetric
digital model of object. The volumetric digital model of the
object is a making component of the graphic database. The
received volumetric digital model is exposed to selective
transformation with the help of functions of computer
modeling. As a result of designing the computer model carrying
the design information for physical object manufacturing
(Gubanov & Vlasov, 2000). In the industrial module the
received computer model will be transformed to the tool control
influences. The made elements can be assembled manually or
automatically with the help of the manipulator. The process of
assembly of discrete layers in integral object formally can be
described by algebraically expression:
n
O = Sj
(5)

j=1 ,
where O - integral object; Sj - a j-layer of object; n –
general quantity of the layers.
5. CONCLUSION
The analysis of the complex 3D-objects creation functional
model has allowed to develop variant of a compact industrial
system. Video system using in this complex allows to solve a
problem of this process information support. It allows also to
speed up a manufacture preparation stage. The development of
mathematical model digitizing and its software allows to create
computer models easily. The application of level-by-level
synthesis allows to make material irregular objects quickly. The
offered variant of compact reverse engineering system allows to
raise production competitiveness.
6. REFERENCES
Gubanov, A. & Vlasov, V. (2000). Computer technologies of
reverse engineering. CAD & Graphics, No 1, pp. 25-29,
ISSN 1560-4640.
Kruth, J. -P. & Kerstens, A. (1997). Reverse engineering
modeling of free-form surfaces from point clouds subject to
boundary conditions. Journal of Materials Processing
Technology, No. 76, pp. 120-127, ISSN 0924-0136.
Makachev, A. & Chaykin, (2000). Modeler 2000: 3D-scaning
systems. CAD & Graphics, No 1, pp. 84-86, ISSN 15604640.
Makachev, A. & Chaykin, (2000). Modeler 2000: 3D-scaning
systems II. CAD & Graphics, No 4, pp. 76-78, ISSN 15604640.
Polozkov, Y. & Zavatsky, Y. (1999). The mathematical
software of irregular surfaces 3D-scaning. Proceedings of
the international conference on the modern trends of
industrial technologies development, Sazonov, I. et. al.
(Ed.), p. 61, ISBN 5-86960-014-6, Mogilev machinebuilding institute, April 1999, MMI, Mogilev.
Authors: Ing. Yuri POLOZKOV, Post-grad. of Vitebsk State
Technological University, 72 Moskowsky ave., 210035
Vitebsk, Belarus, Phone: 375 212 25 55 45 Fax 375 212 25 74
01
Dr. Dmitry SVIRSKY, Science leader of the Computer Aided
Design Centre, Vitebsk State Technological University, 72
Moskowsky ave., 210035 Vitebsk, Belarus, Phone: 375 212 22
70 41 Fax 375 212 25 74 01 E-mail: svirsky@vstu.unibel.by