Appealing Female Avatars from 3D Body Scans: Perceptual Effects of

Stylization

Reuben Fleming

1,2

, Betty J. Mohler

, Javier Romero

, Michael J. Black

and Martin Breidt

Shefﬁeld Hallam University, Shefﬁeld, U.K.

Max Planck Institute for Biological Cybernetics, T

ubingen, Germany

Max Planck Institute for Intelligent Systems, T

ubingen, Germany

Keywords:

3D Body Scan, Stylization, Avatar, Perception, Virtual Character.

Abstract:

Advances in 3D scanning technology allow us to create realistic virtual avatars from full body 3D scan data.

However, negative reactions to some realistic computer generated humans suggest that this approach might

not always provide the most appealing results. Using styles derived from existing popular character designs,

we present a novel automatic stylization technique for body shape and colour information based on a statistical

3D model of human bodies. We investigate whether such stylized body shapes result in increased perceived

appeal with two different experiments: One focuses on body shape alone, the other investigates the additional

role of surface colour and lighting. Our results consistently show that the most appealing avatar is a partially

stylized one. Importantly, avatars with high stylization or no stylization at all were rated to have the least

appeal. The inclusion of colour information and improvements to render quality had no signiﬁcant effect on

the overall perceived appeal of the avatars, and we observe that the body shape primarily drives the change

in appeal ratings. For body scans with colour information, we found that a partially stylized avatar was most

effective, increasing average appeal ratings by approximately 34%.

1 INTRODUCTION

Virtual avatars are frequently used in games, vir-

tual worlds and for online communications. How an

avatar is perceived by others is considered extremely

important but creating a highly detailed and realistic

avatar does not necessarily produce appealing results

(Boberg et al., 2008). Appeal, one of the twelve prin-

ciples of animation (Johnston and Thomas, 1981) is

commonly used to describe well designed, interesting

and engaging characters. In the same way animated

movie and game characters require appeal in order

for people to engage with them, virtual avatars also

require appeal in order to engage others.

In this paper, we explore different ways in which

we can increase the appeal of 3D body scans via styl-

ization. In particular, we explore which styles make

the virtual avatars most appealing, and what is the op-

timal amount of stylization for the most successful

ones. We also examine the role of other factors in the

appeal of the ﬁnal stylized avatar, namely the realism

of the renders and the appearance of the original sub-

ject. For this, we acquire 3D body scans of real people

using a state-of-the-art capturing system and automat-

ically create virtual avatars with different styles and

degrees of stylization. We render these avatars with

and without colour information and also improve the

render quality to simulate varying levels of realism.

We then study, in multiple experiments, which factors

affect the perceived appeal of these avatars.

2 BACKGROUND

Human-like virtual characters are becoming more and

more present in our lives. Since virtual environments

often try to replicate the real world, a natural design

choice for these virtual characters is to make them as

real as possible. This is becoming easier thanks to

the improvements of 3D capturing systems in terms of

speed, accuracy, quality and price. However, not all

virtual characters are designed with reality in mind.

Highly stylized avatars, such as the ones used by the

game consoles Xbox and Wii, seem to suggest that

people ﬁnd the stylized look very appealing. The

stylized approach to avatar creation has traditionally

required the user to manually deﬁne and personalize

their avatar; creating a true resemblance of that person

Fleming, R., Mohler, B., Romero, J., Black, M. and Breidt, M.

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization.

DOI: 10.5220/0005683903330343

In Proceedings of the 11th Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2016) - Volume 1: GRAPP, pages 335-345

ISBN: 978-989-758-175-5

335

is hard to achieve. Game studios are already attempt-

ing to cut out the manual work associated with this

process by capturing gamers’ features and applying

them to in-game characters. For example NBA 2K15

(Take-Two Interactive, 2014) attempts to capture the

player’s face while Kinect Sports Rivals (Microsoft,

2014) captures the entire body. Extracting informa-

tion about the player is currently achieved using pe-

ripherals such as Microsoft’s Kinect 2 and Sony’s PS4

camera.

Despite the availability of both high quality, real-

istic body scans and increasingly convincing avatars

from consumer peripherals, highly stylized characters

are still extremely popular and can be seen in many

animated movies, games and even web-based support

services. Animation companies such as Disney, Blue

Sky and Pixar tend to aim for a highly stylized look

when designing characters. Attempts to increase real-

ism in stylized characters have often led to negative

reactions from viewers (Melina, 2011; Chaminade

et al., 2007). Examples of this include ﬁlms such as

Polar Express (Zemeckis, 2004), Mars Needs Moms

(Wells, 2011), and The Adventures of Tintin (Spiel-

berg, 2011).

Furthermore, negative reactions to the almost, but

not quite, photo-realistic characters seen in some ﬁlm

and game productions (Chaminade et al., 2007) and

the human-like robots that inspired the “Uncanny Val-

ley” hypothesis (Mori et al., 2012) suggest that styl-

izing (therefore decreasing realism), rather than at-

tempting to improve realism, could actually produce

more appealing results. For example, (Inkpen and

Sedlins, 2011) conducted a survey into peoples’ com-

fort when communicating with avatars and found that

although respondents were comfortable interacting

with both realistic and cartoon looking avatars, some

avatars rated highly realistic were also felt to be eerie

or creepy. It is therefore possible that, even if one cre-

ated a photo-real digital replica of a human, a stylized

version could still be more appealing.

Experiments performed by (Seyama and Na-

gayama, 2007), where they morphed between artiﬁ-

cial and real faces, suggest that stylization should be

done consistently in order to avoid viewer discom-

fort as abnormal features (e.g. cartoon eyes applied

to a human head) produced the lowest pleasantness

scores in their experiments. These conclusions match

similar ﬁndings by (MacDorman et al., 2009) who

found that a mismatch between the size and texture

of the eyes and face was especially prone to mak-

ing a character look eerie. Interestingly, again for

faces, results by (McDonnell et al., 2012) suggest that

both highly realistic and highly abstract render styles

were both considered appealing but render styles in-

between the two were considered unappealing. Re-

cently (Zell et al., 2015) found that while face shape

was important for portraying realism, it was the ma-

terial – speciﬁcally the albedo map – that played the

key role in inﬂuencing the perceived appeal of CG

characters and a stylized smooth looking skin texture

(obtained via blurring) was perceived as being more

appealing than a realistic skin texture.

To go beyond previous work on face appeal and

investigate the perceptual effects of stylization on

full-bodied avatars, we conducted two separate ex-

periments. The aim of the ﬁrst experiment was to

investigate the effects of stylization when applied to

a realistic average female body shape containing no

colour information. This allowed us to focus purely

on body shape. In the second experiment we stylized

3D body scans of real people. The aim here was to

assess the effect of the subjects appearance (both in

terms of body shape and colour information) and ren-

der quality on perceived appeal and realism. Overall

the aim of these experiments is to better understand

how to create appealing female avatars from 3D body

scans.

3 STYLIZATION OF 3D BODY

SCANS

3.1 3D Body Scanning

To represent realistic human body shape and appear-

ance we ﬁrst captured detailed 3D body scan and

colour information from 2 female actors (see Fig. 3)

in an A-pose using a full body 3D scanning system

(3dMD USA, 2014).

The system (see Fig. 1) is composed of 22 stereo

units, each including a pair of black and white cam-

eras observing a projected speckle light pattern, and

one 5 megapixel colour camera that captures the body

appearance 2 ms after the speckle image, synchro-

nized with white ﬂash units. The system provides

very good coverage of the entire human body and can

resolve the 3D locations of a point on the body to ap-

proximately 1 mm.

Raw scans contain noise, occasional holes and are

difﬁcult to manipulate. Consequently we registered

a common 3D body template to the scans in order

to obtain a coherent mesh topology for each. For

this we used a statistical 3D body model that com-

pactly parametrises body deformations automatically

in terms of shape changes due to subjects’ identity

and body pose (Hirshberg et al., 2012). The model is

based on approximately 2100 body scans of women

GRAPP 2016 - International Conference on Computer Graphics Theory and Applications

336

Figure 1: Taking a full body scan in the 3D scanning sys-

tem.

from the US and EU CAESAR dataset (Robinette

et al., 2002).

Through this process we obtained 3D geometry

that resembles the original 3D scans but also shares

a common layout. We call these meshes registrations.

Since registrations share mesh topology, their vertex

positions fully describe the body geometry. There-

fore, morphing between two or more bodies can be

performed as a weighted sum of the corresponding

vertex positions across registrations.

Once registered, we extracted both albedo and

pre-lit colour maps (Bogo et al., 2014) from each

scan (using the UV texture coordinate layout deﬁned

in the template). The albedo maps were illuminated

using simple point lights within 3ds Max 2014 (Au-

todesk, USA). The pre-lit colour maps (Fig. 5 right),

provided a more realistic look and, unlike the albedo

maps (Fig. 5 left), required no CG lighting due to the

lighting information already being embedded within

the maps.

3.2 Shape Stylization

For our initial experiment, ﬁve female style tem-

plates were created in the digital sculpting applica-

tion Zbrush (Pixologic, USA) (Fig. 2). The two most

appealing styles were then used again for our second

experiment.

The style templates were created by a trained 3D

artist and were modelled to match the body propor-

tions of existing stylized designs (see Tab. 1). The

style templates used the same topology as the regis-

trations, therefore direct morphing between registra-

tions and style templates was made possible by sim-

ply interpolating vertex positions. While creating the

styles is a time-consuming manual task that requires

a skilled artist, it is worth noting that thanks to the

shared topology, this only needs to be done once and

can then be reused for all future scans.

Table 1: Female style template references.

Style Name Description

Marvel Typical female Marvel superheroine

(Marvel Entertainment, USA)

Disney “Rapunzel” from the animated

movie “Tangled” (Disney, 2010)

Sony “Sam Sparks” from the animated

movie “Cloudy with a Chance of

Meatballs” (Sony, 2009)

Pixar “Princess Merida” from the ani-

mated movie “Brave” (Pixar, 2012)

Barbie “Barbie” doll (Mattel, USA)

Figure 2: Style templates created from character reference.

3.3 Body Shape Generation

For experiment 1 we used an average female body

shape M (Fig. 3 top left). This shape was computed

by averaging the n ≈ 2100 original registrations O

(as

described in section 3.1): M =

∑

i=1

In experiment 2, rather than stylize the average fe-

male body shape, we stylized registrations F obtained

from 3D body scans of real people. In order to main-

tain the characteristic body features (even when fully

stylized) we augmented the resulting morph between

registration F

and template S

with data derived from

the registration: Half of the Euclidean difference be-

tween the mean body shape M and the registration F

was added back to the current body style template S

(right term of Eq. 1). See Fig. 3 for an illustration of

the process.

We obtain the ﬁnal stylized avatar shape N

i, j|α

used for one trial (with identity i, style j and styliza-

tion level α ∈ [0. . . 1]) by linear interpolation between

the original registration F

and the current style tem-

plate S

, augmented by the individual body character-

istics:

i, j|α

= (1 − α) F

+ α



− M)



(1)

This helped to maintain the more subtle characteris-

tics of the original body shape while keeping the over-

all proportions of the stylized models.

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization

337

-1 1

0.5

(1 − α )

2,2

| α=1

1,2

| α=1

Figure 3: Stylization process for style S

(Disney).

Eq. 1 was implemented using the Morpher modi-

ﬁer in 3ds Max, morphing the scans from their origi-

nal state to the 100% stylized model (see Fig. 3 bot-

tom for examples). Two intermediate states were also

generated at 33% and 66% stylization.

3.4 Stylization of Albedo and Pre-lit

Colour Maps

For experiment 2, we used the albedo and pre-lit

colour maps extracted from our scans. These required

some manual clean-up work as they contained vi-

sual marker information (recorded for a different pur-

pose) and had some missing data (Fig. 4). This was

achieved using basic retouching tools and techniques

in Photoshop (Adobe, USA). Note that normally this

step would not be necessary as subjects are scanned

without markers.

Figure 4: Original albedo map (left), cleaned up and grey

body suit added (centre), stylized result (right).

As all actors wore swimwear during scanning, a

grey body suit template was placed over each map

(Fig. 4 centre) to avoid participants becoming dis-

tracted by the clothing. Due to the shared topol-

ogy, and thus the shared UV texture layout, this only

needed to be done once for all characters. To match

the realism of the pre-lit colour maps, a realistic ver-

sion of the suit was rendered using area lights and

global illumination in the V-Ray 2.0 renderer (Chaos

Group, Bulgaria).

The albedo and pre-lit colour maps were also styl-

ized in order to recreate a similar look to most of

the style references. A typical feature ﬁlm anima-

tion look is often represented through heavily satu-

rated colours and soft surface details. To achieve

this, our colour stylization technique was imple-

mented as a Photoshop action and involved Photo-

shop’s edge-preserving Surface Blur ﬁlter and in-

creasing the colour Vibrancy (increasing the satura-

tion of less saturated colours), controlled by masking

regions (Fig. 4 right).

Both the albedo and pre-lit colour maps had a res-

olution of 1024 × 1024 pixels. Parameter α in Eq. 1

was used to linearly blend between the normal and

stylized versions of these maps.

Figure 5: Avatar using CG lit albedo map (left), and pre-lit

colour map with embedded lighting (right).

4 EXPERIMENT 1

We ran a 15 minute experiment with 18 Participants

(10 female, average age = 26.5 yr, SD = 7.5). The ex-

periment was conducted in accordance with the Dec-

laration of Helsinki. All participants signed informed

consent and were ﬁnancially compensated.

4.1 Experimental Design

For our ﬁrst experiment we asked participants for

their judgements of appeal on a 7-pt Likert scale when

observing an average female body shape, as well as

that shape being morphed into 5 different style tem-

plates (Fig. 6) at 3 levels of stylization (33, 66, 100%).

This resulted in a total of 16 avatars (15 for the styl-

ized body and 1 for the average body shape). Stimuli

were presented in a random order. The avatar featured

no colour information and was rendered in real-time

within the Unity 4 game engine (Unity Technologies,

Denmark).

GRAPP 2016 - International Conference on Computer Graphics Theory and Applications

338

Figure 6: Styles used in Experiment 1.

Participants were instructed to answer quickly and

simply provide their ﬁrst impression. Participants

were also given an in-depth deﬁnition of appeal be-

fore they began:

High appeal: “you ﬁnd the person extremely appeal-

ing. This may include ﬁnding the person ex-

tremely engaging, likeable and/or generally pleas-

ing to the eye.”

Average appeal: “you neither ﬁnd the person appeal-

ing nor unappealing. They are acceptable but

essentially you are indifferent, ﬁnding them nei-

ther engaging nor disengaging, likeable nor un-

likeable.”

Low appeal: “you ﬁnd the person extremely unap-

pealing. This may include ﬁnding the person ex-

tremely disengaging, unlikeable and/or repellent.”

4.2 Experiment 1 Results

A partially stylized avatar was often rated as more ap-

pealing than the average female (where the amount

of stylization for optimal appeal depends on the style,

see Fig. 7 and Tab. 2).

We ran a repeated measures ANOVA on the rat-

ing of appeal of avatars in a within subject factors de-

Table 2: Mean appeal ratings by stylization level and style

(standard deviations in parentheses).

Style 33% stylized 66% stylized 100% stylized

Marvel 4.94 (1.211) 5.00 (1.085) 4.17 (1.724)

Disney 4.72 (1.127) 4.83 (1.425) 3.67 (1.847)

Barbie 4.39 (1.195) 4.00 (1.572) 2.33 (1.138)

Pixar 4.39 (1.092) 3.44 (1.504) 2.17 (1.043)

Sony 2.22 (1.003) 1.56 (0.784) 1.28 (0.461)

Percentage Stylized

original 33% 66% 100%

Average Appeal Rating (1-7 Likert)

Average Female

Marvel

Disney

Barbie

Pixar

Sony

Figure 7: Appeal ratings on a 7-pt Likert scale by style

and stylization level (n=18). Ratings for the average female

have been included in this graph as a reference. Error bars

represent one standard error of the mean in all ﬁgures.

sign with two factors: Style (5 levels: Marvel, Disney,

Sony, Pixar, Barbie) and Percent Stylized (3 levels:

33, 66, 100%).

There was a signiﬁcant effect of Percent Stylized

on appeal ratings, F(2,34) = 18.33, p < 0.001, η

= 0.519. 100% stylized had signiﬁcantly lower ap-

peal ratings than both 33% and 66% while both 33%

and 66% stylized avatars were found to be more ap-

pealing than the original body scan (as revealed by

post-hoc comparisons using Bonferroni adjustments,

(p < 0.001)).

There was also a signiﬁcant effect of Style on ap-

peal ratings, F(4,68) = 63.03, p < 0.001, η

= 0.788.

The ﬁve styles did not have the same effect on ap-

peal ratings across percent stylized (as revealed by

post-hoc comparisons using Bonferroni adjustments).

Most notably the Sony style had a signiﬁcantly lower

rating of appeal than all of the styles (p < 0.001) and

was always rated as less appealing than the original

body scan. The appeal ratings of the Marvel and

Disney styles did not signiﬁcantly differ from each

other (p = 1.00) and appeal ratings of the Barbie and

Pixar styles also did not signiﬁcantly differ from each

other (p = 0.907). All other comparisons between

styles resulted in signiﬁcantly different appeal ratings

(p < 0.05).

These main effects were conditioned upon a sig-

niﬁcant interaction between style and percent styl-

ized, F(8,136) = 3.02, p = 0.004, η

= 0.151. We

therefore tested for an effect of percent stylized for

each individual style. The effects of percent stylized

were signiﬁcant for all styles (p < 0.05) except for the

Marvel style (p = 0.12). Not surprisingly, there was a

simple effect of style found when testing at each per-

cent stylized, driven by the low ratings of appeal for

Sony (p < 0.05). In addition, at 100% stylized the

Marvel and Disney appeal ratings were signiﬁcantly

greater than both Barbie and Pixar appeal ratings (as

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization

339

Figure 8: Styles featuring albedo maps and CG lighting.

revealed by post-hoc comparisons using Bonferroni

adjustments, (ps < 0.05)).

These results show that for all styles except Sony,

a partially stylized avatar leads to the greatest appeal

ratings and depending on that style either 33% or 66%

leads to optimal appeal. Excluding the Sony style,

an improvement upon the original appeal ratings for

the average female of approximately 29% could be

achieved by stylizing the body shape.

5 EXPERIMENT 2

Both the Marvel and Disney styles provided the most

signiﬁcant improvements for appeal ratings in exper-

iment 1 and were therefore used to stylize the body

scans of real people in our second experiment.

5.1 Visual Stimuli

For experiment 2, 14 images were rendered in 3ds

Max at 500 × 1000 pixels using our CG lit albedo

maps, 7 rendered images per character: three percent-

ages at two styles each, plus the original body scans

(Fig. 8). Another 14 images were rendered in 3ds

Max using our pre-lit colour maps at the same res-

olution (Fig. 9).

5.2 Experimental Design

There were 61 Participants (35 female) with an aver-

age age of 28.08 yr (SD = 7.6) and none of the par-

ticipants had been involved in experiment 1. The ex-

Figure 9: Styles featuring pre-lit colour maps.

periment was conducted in accordance with the Dec-

laration of Helsinki. All participants signed informed

consent and were compensated. There was no time

limit assigned to the sessions but participants were in-

structed to answer quickly and provide their ﬁrst im-

pression. The experiment lasted approximately one

hour.

There were two tasks in this experiment. First,

subjects provided appeal ratings as in Experiment 1.

Second, participants were asked were asked to dy-

namically create the most appealing and repelling

characters.

5.2.1 Task 1: Likert Scale Ratings

Experiment 2 was a repeated measures design and in-

volved rating avatars on a 5-pt Likert scale and had

three within subject factors: Actor Identity (2 levels:

, F

), Style (2 levels: Marvel, Disney) and Percent

Stylized (3 levels: 33, 66, 100%) and one between

subject factor of Render Quality (2 levels: albedo

maps with CG lighting (42 participants), pre-lit colour

maps without CG lighting (19 participants)).

In addition to appeal, we asked our participants six

further questions (Tab. 3) to see whether our styliza-

tion technique had a signiﬁcant effect on other char-

acter traits

This resulted in a total of 7 questions being asked

for 14 avatars (2 actors × 2 styles × 3 stylization

Our questions were inspired by existing research, e.g.

appeal (McDonnell et al., 2012; McDonnell, 2012) and

sympathy (Hodgins et al., 2010), neuroticism inspired by

the Big Five personality traits (Johnson et al., 1993).

GRAPP 2016 - International Conference on Computer Graphics Theory and Applications

340

levels) + 2 original body scans. We additionally

asked the participants who saw the avatars with pre-

lit colour maps to rate realism. The avatars were pre-

sented in a random order. Questions were asked for

each avatar in the same order as in Table 3.

Table 3: Avatar questionnaire.

1 Do you feel as if you can sympathise with this per-

son?

2 Are you repelled by this person?

3 Would you accept help from this person?

4 Do you ﬁnd this person engaging?

5 How appealing do you ﬁnd this person?

6 How charming do you ﬁnd this person?

7 Does this person come across as being neurotic?

5.2.2 Task 2: Interactive Creation of Appealing

Characters

In a second task, 37 participants were asked to specify

the exact level of stylization they found to be most

appealing/repelling by interactively adjusting a slider

in real-time within the Unity 4 game engine.

In addition to the stylized result controlled by the

slider, the participants were also shown the original

3D body scan next to the avatar they were manipu-

lating, giving them a non-stylized reference. Albedo

maps and CG lighting were used for this task. The

dependent variable was the chosen percentage of styl-

ization and the ﬁxed factor was the style (Marvel and

Disney) and the actor identity (F

and F

). Each trial

always began with the slider value set to 0% (i.e.

showing the original body shape). This resulted in

four trials (two styles for each of the two actor iden-

tities). They were presented in random order. The

instructions were as follows:

“Make this character as appealing as possible.”,

and “Make this character as repelling as possible.”

For this task participants were instructed to take

their time and be as accurate as possible. Participants

were also instructed to adjust the slider once more af-

ter deciding on a level of stylization to verify their

decision before submitting a rating.

5.3 Experiment 2 Results

For the most part responses to our questions show a

similar pattern across percent stylized: an increase in

rating at 33% and a decrease in rating at 100% (as

can be seen in Fig. 10). We decided to analyze only

appeal and realism ratings because appeal seems to

be representative of the majority of the questions in

Table 3. Indeed the mean Appeal rating did not sig-

niﬁcantly differ from all other questions (p < 0.05)

(with the exceptions only being neurotic and repelling

which were inverted in scale). Realism appears to be

the only question that demonstrates a unique pattern

across percent stylized so we analyzed separately re-

alism ratings in the following section.

Percentage Stylized

original 33% 66% 100%

Average Rating (1-5 Likert)

1,5

2,0

2,5

3,0

3,5

4,0

sympathize with

repelled by

accept help

engaging

appealing

charming

neurotic

realistic

Figure 10: Ratings on a 5-pt Likert scale by stylization

level for all questions, collapsed across all styles, identi-

ties and render quality (n=61, n=19 for realism). Note: Re-

pelling and Neurotic ask for negative traits and therefore

have inverted values compared to all other questions asking

for positive traits.

5.3.1 Appeal Ratings Results

Average appeal rating for the original body scans was

2.69. The average appeal ratings for style templates

was 3.49 for Marvel and 3.19 for Disney (see Fig. 11

and Tab. 4).

Percentage Stylized

original 33% 66% 100%

Average Appeal Rating (1-5 Likert)

2.0

2.5

3.0

3.5

4.0

4.5

Disney

Marvel

Disney

Marvel

Figure 11: Appeal ratings on a 5-pt Likert Scale by style,

actor identity and stylization level, collapsed across both

render styles (n=61).

We ran a repeated measures ANOVA on the rat-

ing of appeal of characters with three within subject

factors: Actor Identity (2 levels, F

, F

), Style (2 lev-

els: Marvel, Disney) and Percent Stylized (3 levels:

33, 66, 100%) and one between subject factor of ren-

der quality (2 levels: albedo maps with CG lighting,

pre-lit colour maps without CG lighting).

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization

341

Table 4: Appeal ratings per actor, style and stylization level

(standard deviations in parentheses).

Actor F

Level Marvel Disney Marvel Disney

original 2.56 (1.13) 2.56 (1.13) 2.82 (1.02) 2.82 (1.02)

33% 3.52 (0.96) 3.36 (1.11) 3.62 (0.90) 3.49 (0.92)

66% 3.57 (1.02) 2.89 (1.13) 3.87 (1.02) 3.64 (1.05)

100% 2.93 (0.89) 2.62 (1.11) 3.34 (1.14) 2.89 (1.02)

Surprisingly, we found no signiﬁcant effect of ren-

der style on appeal ratings (albedo maps with CG

lighting versus pre-lit colour maps without CG light-

ing stimuli), F(1,59) = 1.03, p = 0.315, η

= 0.017.

Similar to Experiment 1, we found a signiﬁcant

effect of percent stylized on appeal ratings, F(2,118)

= 19.63, p < 0.001, η

= 0.250. In relative terms, our

method achieves approximately 34% improvement in

appeal ratings for the original body scans by stylizing

at 33% or 66% towards Marvel or Disney styles.

33% and 66% do not signiﬁcantly differ from each

other on appeal ratings (p = 1.0), while 100% styl-

ized is signiﬁcantly lower rated on appeal than both

33% and 66% (p < 0.001, as revealed through post-

hoc comparisons using Bonferroni adjustments)

We also found a signiﬁcant effect of style on ap-

peal ratings, F(1,59) = 16.24, p < 0.001, η

= 0.216.

Marvel is signiﬁcantly higher rated on appeal than

Disney (as revealed through post-hoc comparisons us-

ing Bonferroni adjustments, p < 0.001). Finally, we

found a signiﬁcant effect of actor identity, F(1,59)=

8.66, p < 0.005, η

= 0.128. A stylized female F

is signiﬁcantly lower rated on appeal than a stylized

female F

(as revealed through post-hoc comparisons

using Bonferroni adjustments, p < 0.001).

These effects suggest that all factors (style, actor

identity and percent stylized) inﬂuence the ratings of

appeal. These main effects were conditioned upon a

signiﬁcant interaction between Actor Identity, Style

and Percent Stylized, F(2,118) = 3.45, p = 0.035, η

= 0.055 and a signiﬁcant interaction between Actor

Identity and Percent Stylized F(2,118) = 5.34, p <

0.01,η

= 0.083. The Disney F

at 66% seems to drive

the interaction between Actor Identity, Style and Per-

cent Stylized. This one data point deviates from the

typical pattern of improved appeal at 33%, greater im-

provement at 66% and then a decrease in appeal at

100% stylized, as revealed through post-hoc compar-

isons using Bonferroni adjustments, p < 0.001.

5.3.2 Realism Ratings Results

As a reminder, we only asked realism ratings for the

avatars with pre-lit colour maps. Realism ratings for

the original body scans was on average 3.61. Aver-

age realism for the stylized avatar at 33% was 3.91,

at 66% was 3.54, and at 100% was 2.72 (see Fig. 12

and Tab. 5). Interestingly at 33% stylized there was

no decrease in ratings of realism as compared to the

original scan, at 66% only the Female F

Disney style

received a decreased realism rating and for 100% al-

most all stylized body scans received a signiﬁcantly

lower realism rating.

We ran a repeated measures ANOVA on the rating

of realism of avatars with three within subject factors:

Actor Identity (2 levels, F

, F

), Style (2 Levels: Mar-

vel, Disney) and Percent Stylized (3 levels: 33, 66,

100). Since we had not asked for realism ratings with

the albedo colour map with CG lighting there is no

between subject factor for ratings of realism.

Percentage Stylized

original 33% 66% 100%

Average Realism Rating (1-5 Likert)

2.0

2.5

3.0

3.5

4.0

4.5

Disney

Marvel

Disney

Marvel

Figure 12: Realism ratings on a 5-pt Likert scale by style,

actor identity and stylization level (n=19).

Table 5: Realism ratings per actor identity, style and styl-

ization level (standard deviations in parentheses).

Actor F

Level Marvel Disney Marvel Disney

original 3.47 (1.07) 3.47 (1.07) 3.74 (1.09) 3.74 (1.09)

33% 3.79 (0.79) 4.05 (0.71) 3.84 (0.96) 3.95 (0.78)

66% 3.63 (1.07) 2.95 (0.97) 4.05 (0.71) 3.53 (0.70)

100% 2.74 (0.73) 2.16 (0.50) 3.37 (0.68) 2.63 (0.83)

We found a signiﬁcant effect of Percent Stylized,

F(2,36) =35.042, p < 0.001, η

= 0.661. There was a

signiﬁcant difference between 33, 66 and 100% styl-

ized in realism (as revealed through post-hoc compar-

isons using Bonferroni adjustments, p < 0.05). This

was seen as a decline in realism ratings as stylization

percentage increased.

We found a signiﬁcant effect of style, F(1,18) =

18.841 , p < 0.000, η

= 0.511. Marvel is rated to

have a signiﬁcantly higher realism rating compared

to Disney (as revealed through post-hoc comparisons

using Bonferroni adjustments, p < 0.001). Similarly,

we also found a signiﬁcant effect of actor identity,

F(1,18) = 29.439 ,p < 0.001, η

= 0.621. Consis-

GRAPP 2016 - International Conference on Computer Graphics Theory and Applications

342

tent with appeal ratings, a stylized female F

is rated

signiﬁcantly lower for realism than a stylized female

(as revealed through post-hoc comparisons using

Bonferroni adjustments, p < 0.001).

These main effects were conditioned upon a sig-

niﬁcant interaction between style and percent stylized

F(2,36) = 11.378,p < 0.001, η

= 0.387 and a signif-

icant interaction between actor identity and percent

stylized F(2, 36) = 6.610, p < 0.005, η

= 0.269. This

can be summarized by the styles not changing realism

ratings at 33% stylized, but as stylization increases the

styles and the actors are being perceived with a variety

of different ratings of realism. High levels of Marvel

stylization result in decreased realism ratings for F

but not so for F

, where the Marvel stylization seems

to have the same inﬂuence on realism ratings across

the actors. These results are consistent with our ap-

peal ratings and may shed some light on why 100%

stylization is seen as less appealing, because it is also

seen as less realistic.

5.3.3 Interactive Creation of Characters Results

When asked to interactively create the most appealing

character using sliders it was extremely rare that par-

ticipants chose either the original body scan (3%) or

the fully stylized avatar (5% of the trials). The aver-

age stylization amount chosen was 40.9% across ac-

tors and styles for an appealing character (see Fig. 13

and Tab. 6).

Due to this amodal distribution for the repelling

Figure 13: Original body scan of female F

(left), 38% Dis-

ney (center), 51% Marvel (right). Real-time images cap-

tured from within the Unity 4 game engine.

Table 6: Average stylization level in the method of adjust-

ment task for most appealing character per actor and style

(standard deviations in parentheses).

Style F

Marvel 50.77% (26.3) 45.56% (24.90)

Disney 37.65% (23.3) 29.71% (22.02)

characters we decided to present the histograms for

the percent stylized chosen (see Fig. 14). When

participants were asked to create the most repelling

avatar they chose the 100% stylized version for 58%

of the total trials and the original scan for 24% of the

total trials. This further conﬁrms that the most appeal-

ing avatar is a partially, and speciﬁcally not a fully,

stylized one. These results are also consistent with

the repelling ratings from task 1. However, the de-

gree to which the original body scans and 100% styl-

ized body scans were rated as repelling was only just

above 2 on the 5-pt Likert scale (see Fig. 10). Im-

portant therefore to note is that original body scans

and 100% stylized avatars were not seen as extremely

repelling, but rather more repelling as compared to

partially stylized avatars.

Percentage Stylized

1009080706050403020100

Frequency

12.5%

10.0%

7.5%

5.0%

2.5%

0.0%

Percentage Stylized

1009080706050403020100

Frequency

60.0%

50.0%

40.0%

30.0%

20.0%

10.0%

0.0%

Figure 14: Frequency of stylization level chosen interac-

tively for maximum appealing (top) and repelling characters

(bottom), collapsed across actor identity and style (n=37).

6 DISCUSSION

In general, appeal ratings for the average female body

shape were highest when some level of stylization

was applied (usually 33% but in some cases 66%).

However, not all styles affect the resulting appeal

score in a similar manner. In experiment 1, the Dis-

ney and Marvel stylizations were found to be consis-

tently more appealing than the average female body

shape. Styles with exaggerated body shapes tended

to be rated lower than styles with more human-like

body shapes, with the Barbie and Pixar styles produc-

ing lower appeal ratings than the Disney and Marvel

styles. The Sony style (featuring the most exagger-

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization

343

ated body shape) was rated as being consistently less

appealing than the average female body shape, re-

gardless of the level of stylization applied. This seems

to suggest a preference for human likeness when ob-

serving avatars and a dislike for extremely exagger-

ated proportions. In our second experiment involving

the stylization of body scans with colour information,

we again found that moderate levels of stylization are

effective at increasing appeal since 33% and 66% lev-

els both produced higher appeal ratings than the orig-

inal body scans. However, 100% stylized avatars in

most cases were rated no differently than the origi-

nal body scans. We also found that efforts to make

the avatars appear more realistic (through improve-

ments in render quality) had no signiﬁcant impact on

appeal ratings. Considering our results, it could be

that in contradiction to (Zell et al., 2015), body shape

is playing a larger role in the inﬂuence of perceived

appeal than the inclusion (and modiﬁcation) of sur-

face colour, however further testing is needed to bet-

ter understand this. Realism ratings were consistent

with appeal ratings and may provide some insight as

to why higher levels of stylization are less desirable

than partial stylization, as the highest level of styl-

ization was rated lowest in realism. Interesting, 33%

stylized body scans were not seen as less realistic as

compared to the original body scans. This could be

due to the stylization of the texture drawing attention

away from imperfections in the surface colour. The

fact that there is not an immediate decrease in realism

with stylization also is a result that further supports

the use of stylization to create more appealing avatars.

Additionally, a partially stylized avatar may not suffer

from the Uncanny Valley effect. We hope to further

investigate the perception of realism in more depth to

better understand the role realism plays in the appeal

of our avatars and speciﬁcally further investigate why

our original body scans receive similar realism ratings

as the 33% stylized avatars. A limitation of our ﬁnd-

ings is the small number of templates and body reg-

istrations presented in this paper. We hope to extend

this work by investigating a larger variance in body

shape of actors (i.e. male participants, a wider range

of BMI and different age groups). Most importantly

we would like to increase the number of style tem-

plates that we use to stylize our avatars to be suitable

for a greater variance in the shape of humans.

7 SUMMARY

The stylization technique presented in this paper al-

lows for the semi-automatic creation of more ap-

pealing personalized avatars from 3D body scans for

use in games, virtual environments and online com-

munications.

For stylizing 3D body scans, the main steps are the

automatic registration of a statistical 3D body model

to the body scan data, followed by the stylization

through feature-preserving morphing with colour ﬁl-

tering and blending. Our technique can be automat-

ically applied to any human body scan after registra-

tion of the scan to our 3D body template. The only

manual process involved is the sculpting of the style

templates. However, once created, these can be ap-

plied to an inﬁnite number of body scans and based on

the individual templates, can be applied at the optimal

level of stylization required to maximize the appeal of

these body scans. The rest of the process is fully au-

tomated. Based on the results presented in this paper,

the proposed system can increase appeal ratings by

approximately 34% depending on the actor.

We conducted multiple experiments in which par-

ticipants were asked to rate the appeal of different

avatars. Our results demonstrate that some stylization

(approximately 37%) is perceived as most appealing

on average for our female actors. This suggests that

3D body scans can be made to look more appealing

with some type/level of stylization. Finally, when we

asked our participants to interactively create the most

appealing and repelling avatars from 3D body scans,

we found again that a partially stylized avatar is the

most appealing at approximately 41%. In contrast,

when considering the percent of stylization people

used to create repelling avatars, we found that 82% of

the chosen avatars were made to be either 100% styl-

ized or the original body scans themselves and that a

highly stylized avatar was most often chosen as the

most repelling avatar.

Our results show that partially stylized female 3D

body scans are perceived as most appealing as com-

pared to the original and fully stylized body scans.

ACKNOWLEDGEMENTS

We would like to thank Chris Ferguson, Joe Small-

wood, Anna Wellerdiek and Michael Geuss as well as

all the participants of our experiments and the anony-

mous reviewers.

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344

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