Sophie Jörg

The saliency of anomalies in animated human characters

Virtual characters are much in demand for animated movies, games, and other applications. Rapid advances in performance capture and advanced rendering techniques have allowed the movie industry in particular to create characters that appear very human-like. However, with these new capabilities has come the realization that such characters are yet not quite “right.” One possible hypothesis is that these virtual humans fall into an “Uncanny Valley”, where the viewers emotional response is repulsion or rejection, rather than the empathy or emotional engagement that their creators had hoped for. To explore these issues, we created three animated vignettes of an arguing couple with detailed motion for the face, eyes, hair, and body. In a set of perceptual experiments, we explore the relative importance of different anomalies using two different methods: a questionnaire to determine the emotional response to the full-length vignettes, with and without facial motion and audio; and a 2AFC (two alternative forced choice) task to compare the performance of a virtual “actor” in short clips (extracts from the vignettes) depicting a range of different facial and body anomalies. We found that the facial anomalies are particularly salient, even when very significant body animation anomalies are present.

Investigating the role of body shape on the perception of emotion

In order to analyze the emotional content of motions portrayed by different characters, we created real and virtual replicas of an actor exhibiting six basic emotions: sadness, happiness, surprise, fear, anger, and disgust. In addition to the video of the real actor, his actions were applied to five virtual body shapes: a low- and high-resolution virtual counterpart, a cartoon-like character, a wooden mannequin, and a zombie-like character (Figures 1 and 2). In a point light condition, we also tested whether the absence of a body affected the perceived emotion of the movements. Participants were asked to rate the actions based on a list of 41 more complex emotions. We found that the perception of emotional actions is highly robust and to the most part independent of the characters body, so long as form is present. When motion alone is present, emotions were generally perceived as less intense than in the cases where form was present.

Evaluating the emotional content of human motions on real and virtual characters

In order to analyze the emotional content of motions portrayed by different characters, we created real and virtual replicas of an actor exhibiting six basic emotions: sadness, happiness, surprise, fear, anger and disgust. In addition to the video of the real actor, his actions were applied to five virtual body shapes: a low and high resolution virtual counterpart, a cartoon-like character, a wooden mannequin, and a zombie-like character (Figure 1). Participants were asked to rate the actions based on a list of 41 more complex emotions. We found that the perception of emotional actions is highly robust and to the most part independent of the characters body.

State of the Art in Hand and Finger Modeling and Animation

The human hand is a complex biological system able to perform numerous tasks with impressive accuracy and dexterity. Gestures furthermore play an important role in our daily interactions, and humans are particularly skilled at perceiving and interpreting detailed signals in communications. Creating believable hand motions for virtual characters is an important and challenging task. Many new methods have been proposed in the Computer Graphics community within the last years, and significant progress has been made towards creating convincing, detailed hand and finger motions. This state of the art report presents a review of the research in the area of hand and finger modeling and animation. Starting with the biological structure of the hand and its implications for how the hand moves, we discuss current methods in motion capturing hands, data‐driven and physics‐based algorithms to synthesize their motions, and techniques to make the appearance of the hand model surface more realistic. We then focus on areas in which detailed hand motions are crucial such as manipulation and communication. Our report concludes by describing emerging trends and applications for virtual hand animation.

Data-driven finger motion synthesis for gesturing characters

Capturing the body movements of actors to create animations for movies, games, and VR applications has become standard practice, but finger motions are usually added manually as a tedious post-processing step. In this paper, we present a surprisingly simple method to automate this step for gesturing and conversing characters. In a controlled environment, we carefully captured and post-processed finger and body motions from multiple actors. To augment the body motions of virtual characters with plausible and detailed finger movements, our method selects finger motion segments from the resulting database taking into account the similarity of the arm motions and the smoothness of consecutive finger motions. We investigate which parts of the arm motion best discriminate gestures with leave-one-out cross-validation and use the result as a metric to select appropriate finger motions. Our approach provides good results for a number of examples with different gesture types and is validated in a perceptual experiment.

The perception of finger motions

In this paper, we explore the perception of finger motions of virtual characters. In three experiments, designed to investigate finger animations, we asked the following questions: When are errors in finger motion noticeable? What are the consequences of these errors? What animation method should we recommend? We found that synchronization errors of as little as 0.1s can be detected, but that the perceptibility of errors is highly dependent on the type of motion. Errors in finger animations can change the interpretation of a scene even without altering its perceived quality. Finally, out of the four conditions tested -- original motion capture, no motions, keyframed animation and randomly selected motions -- the original motion captured movements were rated as having the highest quality.

Evaluating the effect of motion and body shape on the perceived sex of virtual characters

In this paper, our aim is to determine factors that influence the perceived sex of virtual characters. In Experiment 1, four different model types were used: highly realistic male and female models, an androgynous character, and a point light walker. Three different types of motion were applied to all models: motion captured male and female walks, and neutral synthetic walks. We found that both form and motion influence sex perception for these characters: for neutral synthetic motions, form determines perceived sex, whereas natural motion affects the perceived sex of both androgynous and realistic forms. These results indicate that the use of neutral walks is better than creating ambiguity by assigning an incongruent motion. In Experiment 2 we investigated further the influence of body shape and motion on realistic male and female models and found that adding stereotypical indicators of sex to the body shapes influenced sex perception. Also, that exaggerated female body shapes influences sex judgements more than exaggerated male shapes. These results have implications for variety and realism when simulating large crowds of virtual characters.

Virtual shapers & movers: form and motion affect sex perception

An experiment to determine factors that influence the perceived sex of virtual characters was conducted. Four different model types were used: highly realistic male and female models, an androgynous character, and a point light walker. Three different types of motion were applied to all models: motion captured male and female walks, and neutral synthetic walks. We found that both form and motion influence sex perception for these characters: for neutral synthetic motions, form determines perceived sex, whereas natural motion affects the perceived sex of both androgynous and realistic forms. These results have implications on variety and realism when simulating large crowds of virtual characters.

Dancing alice: exploring embodied pedagogical strategies for learning computational thinking

n this paper, we introduce an embodied pedagogical approach for learning computational concepts, utilizing computational practices, and developing computational perspectives. During a five-week pilot, a group of students spent after-school time learning the basic elements of dance and then using them to program three-dimensional characters that could perform. Throughout the pilot, we found students consistently standing up in front of their computers and using their bodies to think through the actuation of their characters. Preliminary results suggest that designing a virtual-physical dance performance is a motivating and engaging social context in which to introduce students, especially girls, to alternative applications in computing.

The effect of posture and dynamics on the perception of emotion

Motion capture remains a popular and widely-used method for animating virtual characters. However, all practical applications of motion capture rely on motion editing techniques to increase the reusability and flexibility of captured motions. Because humans are proficient in detecting and interpreting subtle details in human motion, understanding the perceptual consequences of motion editing is essential. Thus in this work, we perform three experiments to gain a better understanding of how motion editing might affect the emotional content of a captured performance, particularly changes in posture and dynamics, two factors shown to be important perceptual indicators of bodily emotions. In these studies, we analyse the properties (angles and velocities) and perception (recognition rates and perceived intensities) of a varied set of full-body motion clips representing the six emotions anger, disgust, fear, happiness, sadness, and surprise. We have found that emotions are mostly conveyed through the upper body, that the perceived intensity of an emotion can be reduced by blending with a neutral motion, and that posture changes can alter the perceived emotion but subtle changes in dynamics only alter the intensity.