M. Carmen Juan

Outlining of the prostate using snakes with shape restrictions based on the wavelet transform (Doctoral Thesis: Dissertation)

This paper considers the problem of deformable contour initialization and modeling for segmentation of the human prostate in medical images. We propose a new technique for elastic deformation restriction to particular object shapes of any closed planar curve using localized multiscale contour parameterization based on the 1D dyadic wavelet transform. For this purpose we define internal curve deformation forces as a result of multiscale parametrical contour analysis. The form restricted contour deformation and its initialization by template matching are performed in a coarse to fine segmentation process based on a multiscale image edge representation containing the important edges of the image at various scales. The method is useful for 3D conformal radiotherapy planning and automatic prostate volume measurements in ultrasonographic diagnosis.

The effects of the size and weight of a mobile device on an educational game

In this paper, we present an educational game for an iPhone and a Tablet PC. The main objective of the game was to reinforce childrens knowledge about the water cycle. The game included different interaction forms like the touch screen and the accelerometer and combined AR mini-games with non-AR mini-games for better gameplay immersion. The main differences between the two devices were screen size and weight. A comparative study to check how these differences affect different aspects was carried out. Seventy-nine children from 8 to 10 years old participated in the study. From the results, we observed that the different characteristics (screen size and weight) of the devices did not influence the childrens acquired knowledge, engagement, satisfaction, ease of use, or AR experience. There was only a statistically significant difference for the global score in which the iPhone was scored higher. We would like to highlight that the scores for the two devices and for all the questions were very high with means of over 4 (on a scale from 1 to 5). These positive results suggest that games of this kind could be appropriate educational games and that the mobile device used may not be a decisive factor.

An Augmented Reality System for Learning the Interior of the Human Body

Augmented Reality has been used for developing systems with learning purposes. In this paper, we present an Augmented Reality system for learning the interior of the human body. We have tested the system with children of the Summer School of the Technical University of Valencia. In this test we have analysed if the use of a Head-Mounted Display or a typical monitor influence in the experience of the children. Results do not offer statistical significant differences using both visualization systems and confirm that children enjoyed learning with the system and consider it as useful tool not only for learning the interior of the human body but also for learning other subjects.

Comparison of the levels of presence and anxiety in an acrophobic environment viewed via hmd or cave

People who suffer from acrophobia fear any situation that involves heights. Several virtual reality systems have been presented to treat this problem. This paper presents a comparison study of the levels of presence and anxiety in an acrophobic environment that is viewed using a computer automatic virtual environment (CAVE) and a head-mounted display (HMD). In this environment, the floor fell away and the walls rose up. To determine whether either of the two visualization systems induced a greater sense of presence/anxiety in non-phobic users, an experiment comparing the two visualization systems was carried out. Twenty-five participants took part in this study. After using each visualization system (HMD or CAVE), the participants were asked to fill out an adapted Slater et al. questionnaire (Slater, Usoh, & Steed, 1994), and a Student t test was applied to the data obtained. The CAVE induces a high level of presence in users. The mean score was 5.01 (where 7 is the maximum value), which was higher than the score obtained using the HMD which was 3.59. The Student t test indicates that there are significant statistical differences. The level of anxiety was also examined at different times during the experiment. The results indicate that both visualization systems provoke anxiety, but that the CAVE provokes more anxiety than the HMD. The animation in which the floor falls away is the one that provoked the most anxiety. The results from the correlation between the anxiety and the level of presence at the three times indicated a significant correlation between the two measures.

A comparative study of the sense of presence and anxiety in an invisible marker versus a marker augmented reality system for the treatment of phobia towards small animals

Phobia towards small animals has been treated using exposure in vivo and virtual reality. Recently, augmented reality (AR) has also been presented as a suitable tool. The first AR system developed for this purpose used visible markers for tracking. In this first system, the presence of visible markers warns the user of the appearance of animals. To avoid this warning, this paper presents a second version in which the markers are invisible. First, the technical characteristics of a prototype are described. Second, a comparative study of the sense of presence and anxiety in a non-phobic population using the visible marker-tracking system and the invisible marker-tracking system is presented. Twenty-four participants used the two systems. The participants were asked to rate their anxiety level (from 0 to 10) at 8 different moments. Immediately after their experience, the participants were given the SUS questionnaire to assess their subjective sense of presence. The results indicate that the invisible marker-tracking system induces a similar or higher sense of presence than the visible marker-tracking system, and it also provokes a similar or higher level of anxiety in important steps for therapy. Moreover, 83.33% of the participants reported that they did not have the same sensations/surprise using the two systems, and they scored the advantage of using the invisible marker-tracking system (IMARS) at 5.19+/-2.25 (on a scale from 1 to 10). However, if only the group with higher fear levels is considered, 100% of the participants reported that they did not have the same sensations/surprise with the two systems, scoring the advantage of using IMARS at 6.38+/-1.60 (on a scale from 1 to 10).

Augmented Reality Interactive Storytelling Systems Using Tangible Cubes for Edutainment

Augmented reality has been used in many areas and it has proved to be useful for storytelling. These systems are adequate for edutainment. In this paper, we present two augmented reality interactive storytelling systems that use tangible cubes. The first shows the story in only one face of the cube and the second presents the story in all visible faces of the cube. The progress of the story can be chosen using two different tangible interfaces. We have tested the systems with the children of the Summer School of the Technical University of Valencia. In these tests we have analysed if the use of a head-mounted display or a typical monitor influence in the experience of the user. Results do not offer statistical significant differences using both visualization systems and confirm that children enjoyed playing with the systems.

An Augmented Reality System for the Treatment of Phobia to Small Animals Viewed Via an Optical See-Through HMD: Comparison With a Similar System Viewed Via a Video See-Through HMD

This article presents an optical see-through (OST) Augmented Reality system for the treatment of phobia to small animals. The technical characteristics of the OST system are described, and a comparative study of the sense of presence and anxiety in a nonphobic population (24 participants) using the OST and an equivalent video see-though (VST) system is presented. The results indicate that if all participants are analyzed, the VST system induces greater sense of presence than the OST system. If the participants who had more fear are analyzed, the two systems induce a similar sense of presence. For the anxiety level, the two systems provoke similar and significant anxiety during the experiment.

Multiresolution segmentation of medical images using shape-restricted snakes

We propose a new technique for elastic deformation restriction of active contour models to particular object shapes. For this purpose we apply localized multi-scale contour parametrization based on the 1D dyadic Wavelet Transform (WT) as a multi-scale boundary curve analysis tool. Our approach determines the WT-coefficients within a certain scale range, which differ significantly from the correspondent WT-coefficients of the most similar model in a training set. Those WT-coefficients are replaced by the correspondent model WT-coefficients to perform the reconstruction of the contour. The difference of the original deformed contour and the reconstructed contour is used as inner snake forces. By this technique it can be avoided, that the deformable contour is trapped into disturbing local minima of the snakes potential due to noise or irrelevant image features. The contour deformation method is integrated in a coarse to fine segmentation frame based on a multiscale image edge representation using the local modulus maxima of the dyadic Wavelet Transform. For detection of the objects position and initialization of the snake we apply a multiresolution binary matched filter at a coarse scale containing few detail information.

MnemoCity task: Assessment of childrens spatial memory using stereoscopy and virtual environments

This paper presents the MnemoCity task, which is a 3D application that introduces the user into a totally 3D virtual environment to evaluate spatial short-term memory. A study has been carried out to validate the MnemoCity task for the assessment of spatial short-term memory in children, by comparing the children’s performance in the developed task with current approaches. A total of 160 children participated in the study. The task incorporates two types of interaction: one based on standard interaction and another one based on natural interaction involving physical movement by the user. There were no statistically significant differences in the results of the task using the two types of interaction. Furthermore, statistically significant differences were not found in relation to gender. The correlations between scores were obtained using the MnemoCity task and a traditional procedure for assessing spatial short-term memory. Those results revealed that the type of interaction used did not affect the performance of children in the MnemoCity task.

Augmented Reality for the Assessment of Children's Spatial Memory in Real Settings

Short-term memory can be defined as the capacity for holding a small amount of information in mind in an active state for a short period of time. Although some instruments have been developed to study spatial short-term memory in real environments, there are no instruments that are specifically designed to assess visuospatial short-term memory in an attractive way to children. In this paper, we present the ARSM (Augmented Reality Spatial Memory) task, the first Augmented Reality task that involves a users movement to assess spatial short-term memory in healthy children. The experimental procedure of the ARSM task was designed to assess the childrens skill to retain visuospatial information. They were individually asked to remember the real place where augmented reality objects were located. The children (N = 76) were divided into two groups: preschool (5–6 year olds) and primary school (7–8 year olds). We found a significant improvement in ARSM task performance in the older group. The correlations between scores for the ARSM task and traditional procedures were significant. These traditional procedures were the Dot Matrix subtest for the assessment of visuospatial short-term memory of the computerized AWMA-2 battery and a parents questionnaire about a childs everyday spatial memory. Hence, we suggest that the ARSM task has high verisimilitude with spatial short-term memory skills in real life. In addition, we evaluated the ARSM tasks usability and perceived satisfaction. The study revealed that the younger children were more satisfied with the ARSM task. This novel instrument could be useful in detecting visuospatial short-term difficulties that affect specific developmental navigational disorders and/or school academic achievement.