proaches for the synthesis of time-varying textures,
while we refer you to some good and comprehensive
surveys on texture synthesis procedures for a general
description and the basics of static textures. See for
instance (Efros and Leung, 1999), (Dischler et al.,
2002).
2.1 Motion in Texture Synthesis
Although many advances have been achieved in tex-
ture synthesis, the lack of control still remains a fo-
cal issue in designing new synthesis techniques. As
recognized by (Lefebvre and Hoppe, 2005), most
techniques that offers some kind of control, only pro-
vide little amount of texture variability and are mainly
restricted to random seeding of boundary conditions,
obtaining rather unpredictable results. Lefebvre and
Hoppe propose texture variability, but their target and
approach differs from ours. They desire an aperiodic
infinite texture that they modify introducing new ele-
ments via drag-and-drop. (Kwatra et al., 2005) visual-
ize textures controlled through a flow field. Neverthe-
less, the approaches are basically different: they use a
global synthesis optimization process, which takes ef-
fect on the whole output texture, while we want local
control and we can manage several texture attributes
(such as resolution, color, shading, embossing besides
orientation) in a general way, in order to provide addi-
tional degrees of freedom for controlled synthesis of
the evolution of texture flow and texture variation.
Regarding statistical methods that model textures
in motion and produce a sort of variation in textures,
they mainly concentrate on repetitive processes and
deal with the modelling and reproduction of tempo-
ral stationarity, like in sea-waves, smoke, steam, fo-
liage, whirlwind but also talking faces, traffic scenes
etc. (see Figure 1). These approaches typically sug-
gest to use a sequence of textured frames to simulate
cyclic motion or periodic effects that are in some way
similar to movement.
For this task, an input sequence of samples - input
movie - is needed. This input has the function of train-
ing data, from which the procedures directly acquire
the necessary information and reproduce it through
statistical learning in an output sequence.
The first approach that gives a statistical character-
ization of textures is the early work of Julesz (Julesz,
1962); successively, about twenty years ago, he intro-
duced (Julesz, 1981) the concept of textons as ”puta-
tive elementary units of texture perception” and there-
with opened the road to a very extensive research, also
in the field of modelling motion in texture.
In recent years, Wei and Levoy (Wei and Levoy,
2000) propose a 3d extension to their model to cre-
ate solid textures or, as particular case, temporal tex-
tures, in case the motion data is local and station-
ary both in space and time. Bar-Josef et al. (Bar-
Figure 1: Temporal regularity is exploited in animation of
clouds, smoke, fire, steam, waves, waterfall.
Joseph et al., 2001) employ multi-resolution analysis
(MRA) of the spatial structure of 2d textures and ex-
tend the idea to dynamic textures (movie texture), they
directly analyze a given input movie and generate a
similar one through statistical learning. Akin to this,
Pullen and Bregler (Pullen and Bregler, 2002) pro-
pose, modelling local dynamics, a multi-level sam-
pling approach to synthesize motion textures:new
(cyclic) motions that are statistically similar to the
original. Li et al. (Li et al., 2002) propose a tech-
nique named motion texture for synthesizing human-
figure motion: they model a motion texton by a Lin-
ear Dynamic System (LDS). Schdl et al. (Schoedl
et al., 2000) also model textons with LDS for video
texture, looping the original frames in a manner that
the synthetic reproduction is minimally noticeable to
the user. Doretto et al. (Doretto et al., 2004) generate
dynamic textures. Dynamic textures are sequences of
images of moving scenes that exhibit temporal regu-
larity, intended in a statistical sense. In the specific
case of spatially coherent textures (textures that ex-
hibit temporal statistics), Soatto et al. (Soatto et al.,
2001) (and (Doretto et al., 2004) for both spatial and
temporal regularity) synthesize a homogenized ver-
sion of the original sequence, through a model de-
signed for maximum-likelihood or minimal predic-
tion error variance. They use LDS to model a tex-
ture by an auto-regressive, moving average (ARMA)
multi-scale process. Similarly, Fitzgibbon (Fitzgib-
bon, 2001) uses an autoregressive (AR) model. Again
for stationary data, Szummer and Picard (Szummer
and Picard, 1996) use a spatial-temporal autoregres-
sive model (STAR), which provides a base for both
recognition and synthesis. This model produces con-
vincing results, nevertheless, it cannot capture curva-
ture and rotational motion.
Modelling more complex variations - nonlinear dy-
namics - is difficult, it requires the use of multiple lin-
ear systems, and thus it is still challenging (see (Li
et al., 2002)).
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