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    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Mixed-Initiative Creative Interfaces for Dynamic Illustration and Generative Design</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Rubaiat Habib Kazi</string-name>
          <email>rubaiat.habib@autodesk.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Justin Matejka</string-name>
          <email>justin.matejka@autodesk.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ben Lafreniere</string-name>
          <email>ben.lafreniere@autodesk.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Autodesk Research</institution>
          ,
          <addr-line>Toronto, ON</addr-line>
          ,
          <country country="CA">Canada</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2017</year>
      </pub-date>
      <fpage>215</fpage>
      <lpage>216</lpage>
      <abstract>
        <p>Modern software applications for design and drawing provide users with rich sets of features, many of which provide computational assistance or otherwise amplify the user's ability to express themselves creatively. In this paper, we present several research projects that we have undertaken in this area, with a focus on how they enable a collaboration between the user and a computational system, and thus reveal potential areas for research on mixed-initiative creative interfaces, and interaction with these kinds of system.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Author Keywords</title>
      <p>Generative design; dynamic illustration;
mixedinitiative creative interfaces</p>
    </sec>
    <sec id="sec-2">
      <title>Introduction</title>
      <p>Software applications for creative tasks ranging from
computer-aided design to sketching have moved far
beyond simply emulating the analog tools that came
before them. Instead, modern design software provides
an environment and rich sets of features that assist the
user in myriad ways. Likewise, software tools for design
and drawing enable creative minds to amplify their
thoughts and express themselves in ways that were
simply not possible using analog tools. In this paper,
we present a number of recent and ongoing projects
that we have undertaken to push the limits of these
domains, with a focus on innovations that enable the
user and the design software system to work in tight
collaboration with one another to produce creative
results.</p>
      <p>The projects we will present suggest several models for
human-machine collaboration in mixed-initiative
creative interfaces that have not been explored in detail
in past work. First, we explore challenges in
representing complex algorithms, simulations, and
dynamics to amplify a user’s ability to understand and
interact with those phenomena. Specifically, we discuss
these ideas in the context of work we’ve undertaken on
dynamic drawings. Second, we discuss the broader
area of generative design, touching on the interaction
challenges of specifying design constraints to a system,
and evaluating the creative outputs generated by a
computational system.</p>
    </sec>
    <sec id="sec-3">
      <title>Dynamic Drawings</title>
      <p>The goal of this line of work is to make animation easy
and accessible to a wider audience, beyond professional
animators. In general, crafting compelling motion
graphics is a challenging task, requiring significant
practice and mastery of complex skills. Artists require a
deep understanding of the complex physical simulations
and dynamics of the effects they are trying to recreate
(e.g., the motion of hair blowing in the wind) to be able
to recreate them effectively. The key challenge for
these types of systems is to provide amateurs with a
set of tools that allow them make use of these complex
dynamics in a way that is easy to learn, apply, and
experiment with.</p>
      <p>
        Our approach aims to break those dynamics into
simple, understandable chunks that are easy to
comprehend and which amplify the user’s
understanding of the dynamics. Below we present two
examples of this approach.
Motion amplifiers [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] bring the exaggerated dynamics
of classical 2D animation into dynamic drawings. We
prototyped a sketching tool that formulates the
principles of 2D animation as a set of motion amplifiers
that can be combined at will. Users can sketch
drawings and record motions through direct
manipulation, and apply the animation principles by
simply tapping on the corresponding amplifier icons
(Figure 1). Each amplifier imposes deformations to an
underlying grid, which in turn updates the
corresponding strokes. The goal of our design is to
increase the user's ability to modularize the
fundamental concepts of 2D animation and combine
them together in new and powerful ways. By
representing the principles of animation in a simplified
manner, our system offers users, particularly those
with no prior experience in animation, the opportunity
to rapidly explore animation effects and produce
expressive animated illustrations.
      </p>
      <p>
        Energy brushes [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. Dynamic effects such as waves,
splashes, fire, smoke, and explosions are an integral
part of stylized animations. However, they are
challenging to produce because they are time-varying
phenomena. We developed an interactive system that
enables artists to design such dynamics by sketching
the underlying forces with energy brushes to animate
drawings and textures. An energy brush creates a
stable, repetitive velocity field pattern by moving flow
particles along the gesture. Complex dynamics, such as
splash, fire, hair, and explosion can be achieved by
combining these simple energy patterns. Our approach
provides artistic controls over coarse and fine scales,
and preserves the fluidity of freeform sketching. Most
importantly, it enables skilled artists, as well as
novices, to integrate complex dynamics into their
animations, by composing them out of simple energy
patterns in an interactive and iterative manner.
Dynamic Drawing as a Mixed-Initiative Creative
Interface
In the projects discussed above, the simulations of
complex dynamics provided by the system can be
viewed as the system’s contribution to a collaborative
creative process with the user. To enable a tight
interactive loop in which both the user and the system
contribute, the complex dynamics are decomposed into
manageable chunks (energy brushes and motion
amplifiers, respectively) which can be understood by
the user and assimilated into their creative process.
There is a connection to what Seymour Papert refers to
as breaking down a complex problem into "mind-size
bites," which makes knowledge more communicable,
more assimilable, and more simply constructible [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
We see this as a potentially valuable model for
humanmachine collaboration in mixed-initiative creative
interfaces. User interfaces for creative tasks that
leverage these “mind-size bites” as a natural
vocabulary to understand and compose complex
phenomena and algorithms might have powerful
influence on how creators think, learn, and explore.
      </p>
    </sec>
    <sec id="sec-4">
      <title>Generative Design</title>
      <p>In generative design systems, a designer provides a set
of design goals and constraints to the system – these
could be material parameters, manufacturing methods,
or cost constraints. The system then generates a range
of design alternatives, in a process that could
potentially produce hundreds or thousands of solutions
that meet the specified constraints. From these, the
designer can select a solution, or iterate on their
specified set of parameters to get a new set of design
alternatives from the system.</p>
      <p>Though generative design is not itself a new concept, it
is only recently that generative design capabilities have
become available in commercial 3D design software,
and researchers have begun to examine the
interactions between human designers and generative
design systems.</p>
      <p>Viewed through the lens of mixed-initiative creative
interfaces, the generative design process presents
several interesting challenges.</p>
      <p>
        First, there is the question of how to enable the human
designer to communicate their goals and constraints to
the generative design system. Current solutions ask the
user to specify physical constraints and forces in a
manner that can be rigid and is often dictated by the
specific generative design algorithms used by the
system. Investigating more natural ways for a user to
express their goals and constraints, or ambiguities in
their goals, is an interesting area for investigation. In
particular, we believe there is an opportunity to learn
from and adapt approaches that have been used in
mixed-initiative interfaces for game-level design [
        <xref ref-type="bibr" rid="ref2 ref4 ref6">2,4,6</xref>
        ]
and generating procedural 3D worlds [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
      <p>Second, there is the question of how best to present
the user with the set designs generated by the system,
which could number in the hundreds or thousands.
Solutions could include interfaces for filtering, ranking,
and visualizing the produced designs. One interesting
possibility in this space is for the system to use implicit
indicators of the user’s interest in produced designs
(e.g., using machine learning techniques), to build a
model of the user’s interests. This could be used to
narrow the space of generated designs, or feed back
into further iterations of the generative design process.
Finally, there are unique interaction challenges raised
by generative design with current technologies. For
example, in 3D shape synthesis, the latency for
generating designs may be on the order of minutes or
hours, which can impede a tight interaction loop
between the designer and the user.</p>
    </sec>
    <sec id="sec-5">
      <title>Conclusions</title>
      <p>In this paper, we have outlined how recent innovations
in design and drawing are creating systems in which
users collaborate actively with computational systems
to produce creative results. We are interested in
contributing to the workshop and helping to define a
research agenda for mixed-initiative creative interfaces
in this domain and more broadly.</p>
    </sec>
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