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Photo 2 - The Puma robot drawing a centaur in space 
with a lamp. 
Laurentiz (dead in 1991), an animation with 
satellite images using Vivaldi’s concert. As 
opposed to the previous proposal, we intend to use 
the information from the satellite images to 
generate the music also, exploring natural 
phenomenons such as vortex, snow and wind, falling 
waters and fire  [Sims, 1990], suggesting the 
movement and the music. Thus, musical parameters 
such as velocity, intensity, duration and timbre 
will be extracted from the images’ information and 
used for the definition of the various states of a 
sound context that will be articulated as a result 
of the images’ trajectories. The pixels of the 
satellite images will be seen as particles in a 
system [Reeves]. 
3.1 Particle Systems 
A particle system is a collection of many minute 
particles that together represent a fuzzy object. 
Over a period of time, particles are generated into 
a system, move and change from within the system, 
and die from the system [Reeves, 83]. 
To compute each frame in a motion sequence, the 
following sequence of steps is performed: (1) new 
particles are generated into the system, (2) each 
new particle is assigned its individual attributes, 
(3) any particles that have existed within the 
system past their prescribed lifetime are 
extinguished, (4) the remainding particles are moved 
and transformed according to their dynamic 
attributes, and finally an image of the living 
particles is rendered in a frame buffer. The 
particle system can be programmed to execute any set 
of  intructions at each step. Because it is 
procedural, this approach can incorporate any 
computational model that describes the appearance or 
dynamics of the object. For example, the motions and 
transformations of particles could be tied to the 
solution of a system of partial differential 
equations, or particle attributes could be assigned 
on the basis of statistical mechanics. 
Particle systems provide for the creation of complex 
structure and motion from a relatively brief 
abstract description. They can be used to produce 
dynamic and "fuzzy" effects that are difficult to 
achieve with traditional objects made of surfaces 
and animated with non-procedural motion. They have 
previously been used to model fire in the Genesis 
Effect of Star Trek II, tree and grass, breaking 
waves, fireworks and other abstract effects. 
We have a particle system being developed at 
Fundaçäo CTI that works with magnetic fields. We 
253 
Will also supply several levels of operations along 
the spectrum between detailed kinematic control and 
physically based simulation. The goal is not to 
strictly obey physics and reality, but to suggest a 
variety of effects easily created. Physical 
simulations can create motion in a much more 
complex and realistic looking than motion achieved 
by moving objects along spline curves or through 
keyframes. Objects animated kinematically often are 
not perceived as dynamically correct, whereas 
objects animated by true physical simulation will 
look correct. 
3.2 Operations with Particles 
Operations used to move particles are divided into 
four categories: those that set the position, those 
that set the velocity, those that alter the position 
or "apply" a velocity, and those that alter the 
velocity or apply an acceleration. In addition to 
position and velocity particles have state variables 
that are used by some animation operations but not 
by others. For example: type, age, mass, 
spiral-axis, color, opacity and size can be used. 
Other spare slots exist for information such as 
initial velocity, a color to fade to, or an age to 
die at. A valuable component of a particle animation 
system is a particle preview capability. 
3.3 The Animation. 
The animation will be obtained from the movement of 
pixels which will be colored using information from 
the different satellite bands. The trajectory will 
be associated to algorithms that describe natural 
phenomenons or the transform operations applied to 
the images [Gonzales, 1977] according to their 
features. This way the *.* Group intend to reveal a 
new America, invoking technological development, 
Nature and Man, by means of its knowledge and its 
sensibility. 
4. ACKNOWLEDGEMENTS 
We thank Josué Guimaráes Ramos for his 
collaboration in supplying many valuable 
explanations about the interpretation of satellite 
images. We also thank the Fundaçäo CTI - Centro 
Tecnolégico para Informética for its support in 
supplying hardware, software and data for this 
development. 
5. BIBLIOGRAPHY 
Franke, H., 1987 
The Beauty of Fractals 
Springer-Verlag 
Laurentiz, P., 1991 
A Holarquia do Pensamento Artístico pp. 93 - 101 
Editora da UNICAMP - UNICAMP - cep 13083 - Brazil 
Gonzalez, R. C. and Wintz, P., 1977 
Digital Image Processingpp. 13 - 114 
Addison-Wesley Publishing Company, Inc. 
Reeves, W., 1983 
Particle Systems - A Technique for Modelling a Class 
of Fuzzy Objects 
ACM Computer Graphics, V. 17, N. 3 
Sins, K-, 1990 
Particle Animation and Rendering using Data Parallel 
Computation 
Computer Graphics, V. 24, N.4, August