Volumetric visualization of 3D data

In recent years, there has been a rapid growth in the ability to obtain detailed data on large complex structures in three dimensions. This development occurred first in the medical field, with CAT (computer aided tomography) scans and now magnetic resonance imaging, and in seismological exploration. With the advances in supercomputing and computational fluid dynamics, and in experimental techniques in fluid dynamics, there is now the ability to produce similar large data fields representing 3D structures and phenomena in these disciplines. These developments have produced a situation in which currently there is access to data which is too complex to be understood using the tools available for data reduction and presentation. Researchers in these areas are becoming limited by their ability to visualize and comprehend the 3D systems they are measuring and simulating

Visualizing Object Oriented Software in Three Dimensions

There is increasing evidence that it is possible to perceive and understand increasingly comple x information systems if they are displayed a s graphical objects in a three dimensional space . Object-oriented software provides an interestin g test case - there is a natural mapping fro m software objects to visual objects . In this paper we explore two areas. 1) Information perception : we are running controlled experiments to determine empirically if our initial premise is valid; how much more (or less) can be understoo d in 3D than in 2D? 2) Layout: our strategy is to combine partially automatic layout with manua l layout. This paper presents a brief overview of the project, the software architecture and some preliminary empirical results

Anatomy: The Relationship Between Internal and External Visualizations

This dissertation explored the relationship between internal and external visualizations and the implications of this relationship for comprehending visuospatial anatomical information. External visualizations comprised different computer representations of anatomical structures, including: static, animated, non-interactive, interactive, non-stereoscopic, and stereoscopic visualizations. Internal visualizations involved examining participants’ ability to apprehend, encode, and manipulate mental representations (i.e., spatial visualization ability or Vz). Comprehension was measured with a novel spatial anatomy task that involved mental manipulation of anatomical structures in three-dimensions and two-dimensional cross-sections. It was hypothesized that performance on the spatial anatomy task would involve a trade-off between internal and external visualizations available to the learner. Results from experiments 1, 2, and 3 demonstrated that in the absence of computer visualizations, spatial visualization ability (Vz) was the main contributor to variation in spatial anatomy task performance. Subjects with high Vz scored higher, spent less time, and were more accurate than those with low Vz. In the presence of external computer visualizations, variation in task performance was attributed to both Vz and visuospatial characteristics of the computer visualization. While static representations improved performance of high- and low-Vz subjects equally, animations particularly benefited high Vz subjects, as their mean score on the SAT was significantly higher than the mean score of low Vz subjects. The addition of interactivity and stereopsis to the displays offered no additional advantages over non-interactive and non-stereoscopic visualizations. Interactive, non-interactive, stereoscopic and non-stereoscopic visualizations improved the performance of high- and low-Vz subjects equally. It was concluded that comprehension of visuospatial anatomical information involved a trade-off between the perception of external visualizations and the ability to maintain and manipulate internal visualizations. There is an inherent belief that increasing the educational effectiveness of computer visualizations is a mere question of making them dynamic, interactive, and/or realistic. However, experiments 1, 2, and 3 clearly demonstrate that this is not the case, and that the benefits of computer visualizations vary according to learner characteristics, particularly spatial visualization ability

Visual Perception and Cognition in Image-Guided Intervention

Surgical image visualization and interaction systems can dramatically affect the efficacy and efficiency of surgical training, planning, and interventions. This is even more profound in the case of minimally-invasive surgery where restricted access to the operative field in conjunction with limited field of view necessitate a visualization medium to provide patient-specific information at any given moment. Unfortunately, little research has been devoted to studying human factors associated with medical image displays and the need for a robust, intuitive visualization and interaction interfaces has remained largely unfulfilled to this day. Failure to engineer efficient medical solutions and design intuitive visualization interfaces is argued to be one of the major barriers to the meaningful transfer of innovative technology to the operating room. This thesis was, therefore, motivated by the need to study various cognitive and perceptual aspects of human factors in surgical image visualization systems, to increase the efficiency and effectiveness of medical interfaces, and ultimately to improve patient outcomes. To this end, we chose four different minimally-invasive interventions in the realm of surgical training, planning, training for planning, and navigation: The first chapter involves the use of stereoendoscopes to reduce morbidity in endoscopic third ventriculostomy. The results of this study suggest that, compared with conventional endoscopes, the detection of the basilar artery on the surface of the third ventricle can be facilitated with the use of stereoendoscopes, increasing the safety of targeting in third ventriculostomy procedures. In the second chapter, a contour enhancement technique is described to improve preoperative planning of arteriovenous malformation interventions. The proposed method, particularly when combined with stereopsis, is shown to increase the speed and accuracy of understanding the spatial relationship between vascular structures. In the third chapter, an augmented-reality system is proposed to facilitate the training of planning brain tumour resection. The results of our user study indicate that the proposed system improves subjects\u27 performance, particularly novices\u27, in formulating the optimal point of entry and surgical path independent of the sensorimotor tasks performed. In the last chapter, the role of fully-immersive simulation environments on the surgeons\u27 non-technical skills to perform vertebroplasty procedure is investigated. Our results suggest that while training surgeons may increase their technical skills, the introduction of crisis scenarios significantly disturbs the performance, emphasizing the need of realistic simulation environments as part of training curriculum

Human factors and performance considerations of visual spatial skills in medical context tasks

In the medical field, stereoscopic applications are present in diagnosis, pre-operative planning, minimally invasive surgery, instruction, and training. The use of stereoscopic applications has afforded new ways to interact with patient data, such as immersive virtual environments. This increased usage of stereoscopic applications also raises many basic research questions on human perception and performance. Current studies show mixed results on the benefits of stereoscopic applications with regards to general performance. The benefits depend on the specific task as well as the application domain. The work presented here attempts to answer the general question: How would adding the stereopsis depth cue affect the performance of visual spatial tasks in a medical context? Visual spatial tasks are needed in medicine to understand the relationships between shapes and organs for a variety of activities in patient diagnosis and treatment. The general research question was decomposed into specific hypotheses and three studies were conducted to study them. These studies measured performance of a visual spatial computer task using medical imaging data. Participants assessed the relative positions of three different objects located inside a 3D volumetric representation of a patient\u27s anatomy. The first study consisted of static views and recognition of the position of color objects. The second study consisted of static views using gray objects. The third study consisted of animated views of color objects. In all three studies the task was basically the same: To select which of two objects was closest to a reference object. In all three studies participants were first and second year medical students. Thirty-four participants completed the first study. The results of this study showed some emerging patterns in which the stereoscopic display condition had a positive benefit on performance. The stereoscopic condition had a positive effect on performance for the most difficult cases but did not yield higher results under every case and condition. The second study, completed by 44 participants, showed the stereoscopic condition had a positive benefit on performance in 20 out of the 40 tasks completed. These 40 tasks were divided into four cases, with varying degrees of difficulty, depending on the distances between the objects being judged (i.e. cylinders in this study). At distances between 5-15 mm, the stereoscopic condition yielded statistically significant higher performance. At other distance ranges, while stereopsis showed improvement it was not statistically significant. Thirty-one participants completed the third study. These participants completed a visual spatial task with the addition of an animation to the volume. This allowed the representation to be viewed from multiple angles before the task was completed. Overall the stereoscopic condition had a benefit in performance over the monoscopic condition. As in the previous studies tasks that had the objects between 5 - 15 mm apart had higher performance in the stereoscopic condition. Females performance in the stereoscopic condition was higher and statistically significant than for the monoscopic condition. Participants over 25 years also had a statistically significant higher performance under the stereoscopic condition. It was also observed that the stereoscopic condition did not outperform the monoscopic one in every condition. The results of these studies show that, in general, stereopsis has a positive benefit in performance for visual spatial tasks in medical contexts. This benefit certainly has a relationship with the difficulty of the task as well as age and gender. These initial insights are a step into further work to help generate design guidelines when developing stereoscopic applications

Could people with stereo-deficiencies have a rich 3D experience using HMDs?

People with stereo-deficiencies usually have problems for the perception of depth using stereo devices. This paper presents a study that involves participants who did not have stereopsis and participants who had stereopsis. The two groups of participants were exposed to a maze navigation task in a 3D environment in two conditions, using a HMD and a large stereo screen. Fifty-nine adults participated in our study. From the results, there were no statistically significant differences for the performance on the task between the participants with stereopsis and those without stereopsis. We found statistically significant differences between the two conditions in favor of the HMD for the two groups of participants. The participants who did not have stereopsis and could not perceive 3D when looking at the Lang 1 Stereotest did have the illusion of depth perception using the HMD. The study suggests that for the people who did not have stereopsis, the head tracking largely influences the 3D experience

VR systems for memory assessment and depth perception

La evolución de la tecnología de Realidad Virtual (RV) ha contribuido en todos los campos, incluyendo la psicología. Esta evolución implica mejoras tanto en hardware como en software, que permiten experiencias más inmersivas. En un entorno de RV los usuarios pueden percibir la sensación de "presencia" y sentirse "inmersos". Estas sensaciones son posibles utilizando HMDs. Hoy en día, el desarrollo de los HMDs se ha centrado en mejorar sus características técnicas para ofrecer inmersión total. En psicología, los entornos de RV son una herramienta de investigación. Hay algunas aplicaciones para evaluar la memoria espacial que utilizan métodos básicos de interacción. Sin embargo, sistemas de RV que incorporen estereoscopía y movimiento físico todavía no se han explotado en psicología. En esta tesis, se ha desarrollado un nuevo sistema de RV que combina características inmersivas, interactivas y de movimiento. El sistema de RV (tarea en un laberinto virtual) se ha utilizado para evaluar la memoria espacial y la percepción de profundidad. Se han integrado dos tipos diferentes de interacción: una basada en locomoción que consistió en pedalear en una bicicleta fija (condición1) y otra estacionaria usando un gamepad (condición2). El sistema integró dos tipos de visualización: 1) Oculus Rift (OR); 2) Una gran pantalla estéreo. Se diseñaron dos estudios. El primer estudio (N=89) evaluó la memoria espacial a corto plazo usando el OR y los dos tipos de interacción. Los resultados indican que existían diferencias significativas entre ambas condiciones. Los participantes que utilizaron la condición2 obtuvieron mejor rendimiento que los que utilizaron la tarea en la condición1. Sin embargo, no se encontraron diferencias significativas en las puntuaciones de satisfacción e interacción entre ambas condiciones. El desempeño en la tarea correlacionó con el desempeño en las pruebas neuropsicológicas clásicas, revelando la verosimilitud entre ellas. El segundo estudio (N=59) incluyó participantes con y sin estereopsis. Este estudio evaluó la percepción de profundidad comparando los dos sistemas de visualización. Los participantes realizaron la tarea usando la condición2. Los resultados mostraron que las diferentes características del sistema de visualización no influyeron en el rendimiento en la tarea entre los participantes con y sin estereopsis. Se encontraron diferencias significativas a favor del HMD entre las dos condiciones y entre los dos grupos de participantes respecto a la percepción de profundidad. Los participantes que no tenían estereopsis y no podían percibir la profundidad cuando utilizaban otros sistemas de visualización, tuvieron la ilusión de percepción de profundidad cuando utilizaron el OR. El estudio sugiere que para las personas que no tienen estereopsis, el seguimiento de la cabeza influye en gran medida en la experiencia 3D. Los resultados estadísticos de ambos estudios han demostrado que el sistema de RV desarrollado es una herramienta apropiada para evaluar la memoria espacial a corto plazo y la percepción de profundidad. Por lo tanto, los sistemas de RV que combinan inmersión total, interacción y movimiento pueden ser una herramienta útil para la evaluación de procesos cognitivos humanos como la memoria. De estos estudios se han extraído las siguientes conclusiones generales: 1) La tecnología de RV y la inmersión proporcionada por los actuales HMDs son herramientas adecuadas para aplicaciones psicológicas, en particular, la evaluación de la memoria espacial a corto plazo; 2) Un sistema de RV como el presentado podría ser utilizado como herramienta para evaluar o entrenar adultos en habilidades relacionadas con la memoria espacial a corto plazo; 3) Los dos tipos de interacción utilizados para la navegación en el laberinto virtual podrían ser útiles para su uso con diferentes colectivos; 4) El OR permite que los usuarios sin estereopsis puedan percibir lThe evolution of Virtual Reality (VR) technology has contributed in all fields, including psychology. This evolution involves improvements in hardware and software allowing more immersive experiences. In a VR environment users can perceive the sensation of "presence" and feel "immersed". These sensations are possible using VR devices as HMDs. Nowadays, the development of the HMDs has focused on improving their technical features to offer full immersion. In psychology, VR environments are research tools because they allow the use of new paradigms that are not possible to employ in a real environment. There are some applications for assessing spatial memory that use basic methods of HCI. However, VR systems that incorporate stereoscopy and physical movement have not yet been exploited in psychology. In this thesis, a novel VR system combining immersive, interactive and motion features was developed. This system was used for the assessment of the spatial memory and the evaluation of depth perception. For this system, a virtual maze task was designed and implemented. In this system, two different types of interaction were integrated: a locomotion-based interaction pedaling a fixed bicycle (condition1), and a stationary interaction using a gamepad (condition2). This system integrated two types of display systems: 1) The Oculus Rift; 2) A large stereo screen. Two studies were designed to determine the efficacy of the VR system using physical movement and immersion. The first study (N=89) assessed the spatial short term memory using the Oculus Rift and the two types of interaction The results showed that there were statistically significant differences between both conditions. The participants who performed the condition2 got better performance than participants who performed the condition1. However, there were no statistically significant differences in satisfaction and interaction scores between both conditions. The performance on the task correlated with the performance on other classical neuropsychological tests, revealing a verisimilitude between them. The second study (N=59) involved participants who had and who had not stereopsis. This study assessed the depth perception by comparing the two display systems. The participants performed the task using the condition2. The results showed that the different features of the display system did not influence the performance on the task between the participants with and without stereopsis. Statistically significant differences were found in favor of the HMD between the two conditions and between the two groups of participants regard to depth perception. The participants who did not have stereopsis and could not perceive the depth when they used other display systems (e.g. CAVE); however, they had the illusion of depth perception when they used the Oculus Rift. The study suggests that for the people who did not have stereopsis, the head tracking largely influences the 3D experience. The statistical results of both studies have proven that the VR system developed for this research is an appropriate tool to assess the spatial short-term memory and the depth perception. Therefore, the VR systems that combine full immersion, interaction and movement can be a helpful tool for the assessment of human cognitive processes as the memory. General conclusions from these studies are: 1) The VR technology and immersion provided by current HMDs are appropriate tools for psychological applications, in particular, the assessment of spatial short-term memory; 2) A VR system like the one presented in this thesis could be used as a tool to assess or train adults in skills related to spatial short-term memory; 3) The two types of interaction (condition1 and condition2) used for navigation within the virtual maze could be helpful to use with different collectives; 4) The Oculus Rift allows that the users without stereopsis can perceive the depth perception of 3D objects and have rich 3D experiences.L'evolució de la tecnologia de Realitat Virtual (RV) ha contribuït en tots els camps, incloent la psicologia. Aquesta evolució implica millores en el maquinari i el programari que permeten experiències més immersives. En un entorn de RV, els usuaris poden percebre la sensació de "presència" i sentir-se "immersos". Aquestes sensacions són possibles utilitzant HMDs. Avui dia, el desenvolupament dels HMDs s'ha centrat a millorar les seves característiques tècniques per oferir immersió plena. En la psicologia, els entorns de RV són eines de recerca. Hi ha algunes aplicacions per avaluar la memòria espacial que utilitzen mètodes bàsics d'interacció. Tanmateix, sistemes de RV que incorporen estereoscòpia i moviment físic no s'han explotat en psicologia. En aquesta tesi, s'ha desenvolupat un sistema de RV novell que combina immersió, interacció i moviment. El sistema (tasca en un laberint virtual) s'ha utilitzat per a l'avaluació de la memòria espacial i la percepció de profunditat. S'han integrat dos tipus d'interacció: una interacció basada en locomoció pedalejant una bicicleta fixa (condició1), i l'altra una interacció estacionària usant un gamepad (condició2). S'han integrat dos tipus de sistemes de pantalla: 1) L'Oculus Rift; 2) Una gran pantalla estereoscòpica. Dos estudis van ser dissenyats. El primer estudi (N=89) va avaluar la memòria a curt termini i espacial utilitzant l'Oculus Rift i els dos tipus d'interacció. Els resultats indiquen que hi havia diferències significatives entre les dues condicions. Els participants que van utilitzar la condició2 van obtenir millor rendiment que els participants que van utilitzar la condició1. Tanmateix, no hi havia diferències significatives dins satisfacció i puntuacions d'interacció entre les dues condicions. El rendiment de la tasca va correlacionar amb el rendiment en les proves neuropsicològiques clàssiques, revelant versemblança entre elles. El segon estudi (N=59) va implicar participants que van tenir i que van haver-hi no estereopsis. Aquest estudi va avaluar la percepció de profunditat comparant els dos sistemes de pantalla. Els participants realitzen la tasca utilitzant la condició2. Els resultats van mostrar que les diferents característiques del sistema de pantalla no va influir en el rendiment en la tasca entre els participants qui tenien i els qui no tenien estereopsis. Diferències significatives van ser trobades a favor del HMD entre les dues condicions i entre els dos grups de participants. Els participants que no van tenir estereopsis i no podien percebre la profunditat quan van utilitzar altres sistemes de pantalla (per exemple, CAVE), van tenir la il.lusió de percepció de profunditat quan van utilitzar l'Oculus Rift. L'estudi suggereix que per les persones que no van tenir estereopsis, el seguiment del cap influeix en gran mesura en l'experiència 3D. Els resultats estadístics dels dos estudis han provat que el sistema de RV desenvolupat per aquesta recerca és una eina apropiada per avaluar la memòria espacial a curt termini i la percepció de profunditat. Per això, els sistemes de RV que combinen immersió plena, interacció i moviment poden ser una eina útil per la avaluació de processos cognitius humans com la memòria Les conclusions generals que s'han extret d'aquests estudis, són les següents: 1) La tecnologia de RV i la immersió proporcionada pels HMDs són eines apropiades per aplicacions psicològiques, en particular, la avaluació de memòria espacial a curt termini; 2) Un sistema de RV com el presentat podria ser utilitzat com a eina per avaluar o entrenar adults en habilitats relacionades amb la memòria espacial a curt termini; 3) Els dos tipus d'interacció utilitzats per navegació dins del laberint virtual podrien ser útils per al seu ús amb diferent col.lectius; 3) L'Oculus Rift permet que els usuaris que no tenen estereopsis puguen percebre la percepció de profunditat dels objectes 3D i tenirCárdenas Delgado, SE. (2017). VR systems for memory assessment and depth perception [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/94629TESI

Stereoscopic three-dimensional visualisation technology in anatomy learning: A meta-analysis

Objectives: The features that contribute to the apparent effectiveness of three-dimensional visualisation technology [3DVT] in teaching anatomy are largely unknown. The aim of this study was to conduct a systematic review and meta-analysis of the role of stereopsis in learning anatomy with 3DVT. Methods: The review was conducted and reported according to PRISMA Standards. Literature search of English articles was performed using EMBASE, MEDLINE, CINAHL EBSCOhost, ERIC EBSCOhost, Cochrane CENTRAL, Web of Science and Google Scholar databases until November 2019. Study selection, data extraction and study appraisal were performed independently by two authors. Articles were assessed for methodological quality using the Medical Education Research Study Quality Instrument and the Cochrane Collaboration's tool for assessing the risk of bias. For quantitative analysis, studies were grouped based on relative between-intervention differences in instructional methods and type of control conditions. Results: A total of 3934 citations were obtained of which 67 underwent a full-text review. Ultimately, 13 randomised controlled trials were included in the meta-analysis. When interactive, stereoscopic 3D models were compared to interactive, monoscopic 3D models within a single level of instructional design, for example isolating stereopsis as the only true manipulated element in the experimental design, an effect size [ES] of 0.53 (95% confidence interval [CI] 0.26-0.80; P <.00001) was found. In comparison with 2D images within multiple levels of instructional design, an effect size of 0.45 (95% CI 0.10-0.81; P <.002) was found. Stereopsis had no effect on learning when utilised with non-interactive 3D images (ES = −0.87, 95% CI −2.09-0.35; P =.16). Conclusion: Stereopsis is an important distinguishing element of 3DVT that has a significant positive effect on acquisition of anatomical knowledge when utilised within an interactive 3D environment. A distinction between stereoscopic and monoscopic 3DVT is essential to make in anatomical education and research

Stereoscopic bimanual interaction for 3D visualization

Virtual Environments (VE) are being widely used in various research fields for several decades such as 3D visualization, education, training and games. VEs have the potential to enhance the visualization and act as a general medium for human-computer interaction (HCI). However, limited research has evaluated virtual reality (VR) display technologies, monocular and binocular depth cues, for human depth perception of volumetric (non-polygonal) datasets. In addition, a lack of standardization of three-dimensional (3D) user interfaces (UI) makes it challenging to interact with many VE systems. To address these issues, this dissertation focuses on evaluation of effects of stereoscopic and head-coupled displays on depth judgment of volumetric dataset. It also focuses on evaluation of a two-handed view manipulation techniques which support simultaneous 7 degree-of-freedom (DOF) navigation (x,y,z + yaw,pitch,roll + scale) in a multi-scale virtual environment (MSVE). Furthermore, this dissertation evaluates auto-adjustment of stereo view parameters techniques for stereoscopic fusion problems in a MSVE. Next, this dissertation presents a bimanual, hybrid user interface which combines traditional tracking devices with computer-vision based "natural" 3D inputs for multi-dimensional visualization in a semi-immersive desktop VR system. In conclusion, this dissertation provides a guideline for research design for evaluating UI and interaction techniques