L'objectif principale de la Réalité Mixte (RM) est de donner aux utilisateurs l'illusion que les objets virtuels et réels coexistent indistinctement dans le même espace. Une illusion efficace nécessite un recalage précis entre les deux mondes. Ce recalage doit être cohérent du point de vue géométrique et photométrique. Dans cette thèse, nous proposons de nouvelles méthodes de recalage photométrique pour estimer l'illumination et la réflectance de scènes réelles. Plus précisément, nous proposons des approches en nous attaquant à trois grands défis : (1) utilisation d'une seule caméra RGB-D. (2) estimation des propriétés de réflectance diffuse et spéculaire. (3) estimation de la position 3D et de la couleur de sources lumineuses dynamiques multiples. Dans notre première contribution, nous considérons des scènes réelles d’intérieurs où la géométrie et l'éclairage sont statiques. En observant la scène à partir d’une caméra mobile, des réflexions spéculaires peuvent être détectées tout au long de la séquence d'images RGB-D. Ces indices visuels sont très instructifs sur l'éclairage et la réflectance des surfaces des scènes. Par conséquent, nous les modélisons pour estimer à la fois les propriétés de réflectance diffuse et spéculaire ainsi que la position 3D de sources lumineuses multiples. Notre algorithme permet d'obtenir des résultats de RM convaincants tels que des ombres virtuelles réalistes ainsi qu'une suppression correcte de la spécularité réelle. Les ombres sont omniprésentes et représentent l’occultation de la lumière par la géométrie existante. Elles représentent donc des indices intéressants pour reconstituer les propriétés photométriques de la scène. La présence de texture dans ce contexte est un scénario critique. En effet, la séparation de la texture et des effets d'éclairage est souvent gérée par des approches qui nécessitent l’intervention de l'utilisateur ou qui ne répondent pas aux exigences du temps de traitement de la réalité mixte. Nous abordons ces limitations et proposons une méthode d'estimation de la position et de l'intensité des sources lumineuses. L'approche proposée gère les lumières dynamiques et fonctionne en temps quasi-réel. L'existence d'une source lumineuse est plus probable si elle est soutenue par plus d'un indice visuel. Nous abordons donc le problème de l'estimation des propriétés d’éclairage et de réflectance en analysant conjointement les réflexions spéculaires et les ombres projetées. L'approche proposée tire parti de l'information apportée par les deux indices pour traiter une grande variété de scènes. Notre approche est capable de traiter n'importe quelle surface texturée et tient compte à la fois des sources lumineuses statiques et dynamiques. Son efficacité est démontrée par une gamme d'applications, incluant la réalité mixte et la re-texturation. La détection des ombres projetées et des réflexions spéculaires étant au cœur de cette thèse, nous proposons finalement une méthode d'apprentissage approfondi pour détecter conjointement les deux indices visuels dans des scènes réelles d’intérieurs. / The overarching goal of Mixed Reality (MR) is to provide the users with the illusion that virtual and real objects coexist indistinguishably in the same space. An effective illusion requires an accurate registration between both worlds. This registration must be geometrically and photometrically coherent. In this thesis, we propose novel photometric registration methods to estimate the illumination and reflectance of real scenes. Specifically, we propose new approaches which address three main challenges: (1) use of a single RGB-D camera. (2) estimation of both diffuse and specular reflectance properties. (3) estimation of the 3D position and color of multiple dynamic light sources. Within our first contribution, we consider indoor real scenes where both geometry and illumination are static. As the sensor browses the scene, specular reflections can be observed throughout a sequence of RGB-D images. These visual cues are very informative about the illumination and reflectance of scene surfaces. Hence, we model these cues to recover both diffuse and specular reflectance properties as well as the 3D position of multiple light sources. Our algorithm allows convincing MR results such as realistic virtual shadows and correct real specularity removal. Shadows are omnipresent and result from the occlusion of light by existing geometry. They therefore represent interesting cues to reconstruct the photometric properties of the scene. Presence of texture in this context is a critical scenario. In fact, separating texture from illumination effects is often handled via approaches which require user interaction or do not satisfy mixed reality processing time requirements. We address these limitations and propose a method which estimates the 3D position and intensity of light sources. The proposed approach handles dynamic light sources and runs at an interactive frame rate. The existence of a light source is more likely if it is supported by more than one cue. We therefore address the problem of estimating illumination and reflectance properties by jointly analysing specular reflections and cast shadows. The proposed approach takes advantage of information brought by both cues to handle a large variety of scenes. Our approach is capable of handling any textured surface and considers both static and dynamic light sources. Its effectiveness is demonstrated through a range of applications including real-time mixed reality and retexturing. Since the detection of cast shadows and specular reflections are at the heart of this thesis, we further propose a deep-learning framework to jointly detect both cues in indoor real scenes.

Motion capture is the process to record the movement of a human. To accomplish this, a hybrid tracking system is used. It combines an optic tracking system with a magnetic one to compensate shortcomings and effectively use their advantages. Another part of this work copes with the conversion of the tracking data into skeletal information and related topics like skeleton definition, skeleton fitting or parameterization of joint rotations. / Mittels Motion Capture werden die Bewegungen eines Menschen in computerlesbare Form überführt. Dazu wird ein hybrides Trackingsystem verwendet, das durch Kombination eines optischen mit einem magnetischen System entsteht und die Schwächen der Einzelsysteme kompensiert. Neben der Realisierung dieses Hybridsystems steht die Übertragung der gewonnenen Bewegungsdaten auf ein Skelettmodell und damit verbundene Fragen, wie Skelettdefinition, Skelettanpassung oder Beschränkung der Gelenkrotationen im Vordergrund.

Unilateral spatial neglect (USN) is a common disorder after stroke. An application especially developed for stroke rehabilitation, the RehAtt Mixed Reality (MR) intends to train cognitive and motor functions that are affected by USN, by the means of interactive 3D games played in mixed reality, through smart glasses. The present study targets one specific cognitive function, namely spatial attention, and compares individual performances in one of the games (scenarios) to performances in a widely used test for detection of deficits in spatial attention – the Posner test. The hypothesis is that user reaction times in the RehAtt MR scenario correlates with user reaction times in the Posner test. Another test, including a questionnaire, to validate the usability of the RehAtt MR is also conducted. The sample for the usability test and questionnaire includes a total of 74 participants (47 women, 27 men, M = 39.6 years of age), of which 29 individuals (13 women, 16 men, M = 35 years of age) carried out the experimental part of the study. The results suggest that there is a significant correlation, r(27) = .411, p = .027, between reaction times in the Posner test and the scenario in the RehAtt MR, and that the product usability shows high quality. It is concluded that the results support that the scenario explored in the RehAtt MR trains spatial attention, although further research is needed for full validation. / Unilateraltspatialt neglekt (USN) är en vanlig funktionsnedsättning efter stroke. En applikation som utvecklats speciellt för strokerehabilitering - RehAtt Mixed Reality (MR) - har som mål att träna kognitiva och motoriska funktioner som är påverkade av USN, med hjälp av 3D-spel som spelas i mixed reality, genom smarta glasögon. Den aktuella studien siktar in sig på en specifik kognitiv funktion – spatial uppmärksamhet – och jämför individuella prestationer i ett av spelen i RehAtt MR med prestationer i ett vanligt, ofta använt test för att upptäcka nedsättningar i spatial uppmärksamhet – Posner-testet. Hypotesen är att användares reaktionstider i spelet i RehAtt MR korrelerar med användares reaktionstider i Posner-testet. Ett annat test, inklusive en enkät, görs också, för att validera användbarheten i RehAtt MR. 74 deltagare (47 kvinnor, 27 män, M = 39.6 år) finns med i användbarhetstestet och enkäten, av vilka 29 individer (13 kvinnor, 16 män, M = 35 år) medverkade i den experimentella delen av studien. Resultaten indikerar att det är en signifikant korrelation, r(27) = .411, p = .027, mellan reaktionstiderna i Posner-testet och spelet i RehAtt MR, och att användbarheten hos produktenvisar hög kvalitet. Slutsatsen är att vad som hittats i den aktuella studien stödjer idéen att spelet i RehAtt MR tränar spatial uppmärksamhet, även om vidare studier krävs för en full validering.

When developing new active safety systems or improving existing systems, conducting performance evaluations is necessary. By performing these evaluations during early development stages, potential problems can be identified and mitigated before the system moves into the production phase. Testing active safety systems can be difficult since the characteristic scenarios may have complex interactions. Using real vehicles for performing these types of scenarios is difficult, expensive, and potentially dangerous. Alternative methods, such as using inflatable targets, scale models, computer simulations or driving simulators, also suffer from drawbacks. Consequently, using virtual reality as an alternative to the traditional methods has been proposed. In this case, a real vehicle is driven while wearing a head-mounted display that presents the scenario to the driver. This research aims to investigate the potential of such technology. Specifically, this work investigates how the chosen technology affects the driver. This investigation has been conducted through a literature review. A test platform was constructed, and two user studies using normal drivers were performed. The first study focused on the effects of visual time delays on driver behavior. This study revealed that lateral behavior changes with added time delays, whereas longitudinal behavior appears unaffected. The second study investigated how driver behavior is affected by different modes of virtuality. This study demonstrated that drivers perceived mixed reality as more difficult than virtual reality. The main contribution of this work is the detailed understanding of how time delays and different modes of virtuality affect drivers. This is important knowledge for selecting which scenarios are suitable for evaluation using virtual reality. / <p>The series name <em>Linköping Studies in Science and Technology Licentiate Thesis</em> is incorrect. The correct series name is <em>Linköping Studies in Science and Technology Thesis</em>.</p>

During an extravehicular activity (EVA), the role of an astronaut involves a multitude of complex tasks. Whether that task is a science experiment aboard the International Space Station, or traversing extraterrestrial terrain – attention, communication, and instruction are essential. As an aid, augmented reality (AR) can portray suit informatics and procedures within line-of-sight while minimizing attentional loss. Currently, there exists little research highlighting the human systems considerations to qualify AR systems for space suit applications. This study quantifies user interface (UI) and human performance measures for an AR prototype on the Mark III space suit. For user testing, 21 military pilots and personnel (11 men, 10 women) evaluated UI search tasks and completed a series of AR-instructed EVA dexterity tasks in an elevated luminosity, background clutter, and workload scenario. UI results suggest correlations for readability and usability; whereas, human performance results provide situational awareness, workload, and task performance data.

The underestimation of depth in virtual environments at mediumield distances is a well studied phenomenon. However, the degree by which underestimation occurs varies widely from one study to the next, with some studies reporting as much as 68% underestimation in distance and others with as little as 6% (Thompson et al. [38] and Jones et al. [14]). In particular, the study detailed in Jones et al. [14] found a surprisingly small underestimation effect in a virtual environment (VE) and no effect in an augmented environment (AE). These are highly unusual results when compared to the large body of existing work in virtual and augmented distance judgments [16, 31, 36–38, 40–43]. The series of experiments described in this document attempted to determine the cause of these unusual results. Specifically, Experiment I aimed to determine if the experimental design was a factor and also to determine if participants were improving their performance throughout the course of the experiment. Experiment II analyzed two possible sources of implicit feedback in the experimental procedures and identified visual information available in the lower periphery as a key source of feedback. Experiment III analyzed distance estimation when all peripheral visual information was eliminated. Experiment IV then illustrated that optical flow in a participant’s periphery is a key factor in facilitating improved depth judgments in both virtual and augmented environments. Experiment V attempted to further reduce cues in the periphery by removing a strongly contrasting white surveyor’s tape from the center of the hallway, and found that participants continued to significantly adapt even when given very sparse peripheral cues. The final experiment, Experiment VI, found that when participants’ views are restricted to the field-of-view of the screen area on the return walk, adaptation still occurs in both virtual and augmented environments.

This work has investigated how head-mounted-displays can enable more efficient and better work conditions for warehouse workers. Head-mounted-displays have increased in popularity among companies because of an increase in the field of e-commerce, therefore warehouse labour was an interesting area to review. The purpose of this project has been to investigate how head-mounted-displays can simplify warehouse work and to find an area where Tangar can be utilized. Tangar is an application to facilitate indoor navigation by helping users to reach points of interest. Through a mixed methodology approach that utilizes both quantitative and qualitative methods, a broad understanding in warehouse and inventory management have been established. The potentials of head-mounted display were evaluated using empirical and theoretical studies. Based on an early concept that was evaluated by a collaboration with a warehouse-solution company, factors that are of importance in warehouse management were identified. A decision to direct the project towards order picking was taken as it is a fundamental process within warehouse management. Three concepts were generated that harness the benefits of head-mounted-displays. With an informed decision the benefits for each of the concepts were compared with important parameters for a profitable warehouse management. It turned out that "Pick-by-Light", a common system in warehouse management, can be made virtual using head-mounted-displays. Since the system had never previously been operated virtually, an extensive study needed to be done in order to evaluate the viability in order-picking to propose a final concept. An experimental environment was set for the empirical studies, and two other common order picking systems were compared to the virtual Pick-by-Light system. Quantitative data in the form of time measurements from the order picking as well as picking errors and qualitative data from a NASA-TLX survey, was extracted from twelve users. A total of 360 samples from the quantitative study and 36 questionnaires from the qualitative study was then analysed. The result resembled those from similar studies with a conventional Pick-by-Light system. Thus, parallels were drawn that indicated that the virtual system had good potential to perform at least as well as a regular Pick-by-Light. A virtual Pick-by-Light system might be able to reduce implementation-, work- and operational costs as the use of material is replaced by a virtual product, and also no installation is required. With the combination of Tangar, there is also a potential that a virtual Pick-by-Light system could be more efficient and accurate. The disadvantages of the conventional Pick-by-Light system are also that confirmations are ineffective and that workers find it difficult to get an overview of pickplaces. Which can potentially be eliminated with the proposed concept. However, a new generation of hardware and further studies are required in order to establish a final concept. The Magic Leap One, which is the head-mounted-display used in the project, is new. Many problems regarding the display have been discovered during the project and affected the results of the user studies. Further studies need to be done with other displays to determine the validity of the results of this work. In summary, this work gives an introduction in how "Mixed-reality" can be used in warehouse management and recommendations for continued work. / Det här arbetet har undersökt hur huvudmonterade skärmar kan möjliggöra ett effektivare och bättre arbete för lager-personal. Huvudmonterade skärmar har ökat i popularitet bland företaget på grund av ökningen inom e-handel och därför var lagerarbete ett intressant område att undersöka. Syftet med det här projektet har varit att undersöka hur huvudmonterade skärmar fortsatt skulle kunna förenkla lagerarbete samt att ta hitta ett område där Tangar kan användas. Tangar är en applikation som förenklar inomhus navigering genom att leda användaren till valda intressepunkter. Genom en metodisk undersökning som utnyttjar både kvantitativa och kvalitativa metoder, har en bred bakgrund inom lagerhantering kunnat upprättas. Potentialen av att använda huvudmonterade skärmar har undersökts genom empiriska och teoretiska studier. Baserat på ett tidigt koncept som utvärderas genom ett samarbete med ett sakkunnigt företag, identifierades flertalet faktorer som är av vikt i lagerhantering. Ett beslut om att rikta projektet mot order-plockning togs då det är en fundamental process inom lagerabete. Tre koncept genererades som utnyttjar fördelarna med huvudmonterade skärmar. Genom att ta ett informativt beslut, kunde fördelarna för var och ett av koncepten jämföras med viktiga parametrar för ett lönsamt lagerarbete. Det visade sig att ”Pick-by-Light”, ett vanligt system inom lagerhantering, kunde göras virtuellt med hjälp av huvudmonterade skärmar. I och med att systemet tidigare aldrig utförts virtuellt, behövdes en omfattande studie göras för att evaluera dess potential inom order-plockning för att kunna föreslå ett slutgiltigt koncept. En experimentell miljö sattes upp som ram för de empiriska studierna och två andra vanliga order-plocknings system kunde jämföras mot det virtuella Pick-by-Light systemet. Kvantitativa data i form av orderplockningstider samt plock-fel och kvalitativa data från observationer samt en NASA-TLX enkät, kunde extraheras från tolv användare. Totalt kunde 360 stickprov från den kvantitative studien och 36 enkäter från den kvalitative studien därefter analyseras. Resultatet liknade det som observerats i liknande studier där ett vanligt Pick-by-Light system evaluerats. Därmed kunde paralleller dras som visade att det virtuella systemet hade god potential till att kunna prestera åtminstone lika bra som ett vanliga Pick-by-Light systemet och ett koncept togs fram för vidare utveckling. Ett virtuellt Pick-by-Light system skulle kunna reducera implementerings-, arbetes- samt driftkostnader i och med att materialåtgången ersätts av en virtuell produkt, samt att ingen installation krävs. I och med kombinationen av Tangar finns det även potential att konceptet är mer effektivt och exakt. De nackdelar med det traditionella Pick-by-Light systemet är också att plock-bekräftelser görs ineffektivt och att arbetare har svårt att få en överblick gällande plockställen. Vilket skulle kunna elimineras med det föreslagna konceptet. Dock krävs en ny generation hårdvara och vidare studier för att kunna fastställa ett slutgiltigt koncept. Magic Leap One, som är den huvudmonterade skärmen som används i projektet är väldigt ny. Många problem gällande displayen har upptäckts under projektet och påverkat resultatet av användarstudierna. Fortsatta studier skulle behöva göras med andra displayer för att fastställa validiteten av resultaten från det här arbetet. Sammanfattningsvis ger det här arbetet en introduktion om hur ”Mixed-reality” kan användas inom lagerhantering samt rekommendationer till fortsatt arbete.

A virtual environment is a set of surroundings that appears to exist to a user through sensory stimuli provided by a computer. By virtual environment, we mean to include environments supporting the full range from VR to pure reality. A necessity for virtual environments is knowledge of the location of objects in the environment. This is referred to as the tracking problem, which points to the need for accurate and precise tracking in virtual environments. Marker-based tracking is a technique which employs fiduciary marks to determine the pose of a tracked object. A collection of markers arranged in a rigid configuration is called a tracking probe. The performance of marker-based tracking systems depends upon the fidelity of the pose estimates provided by tracking probes. The realization that tracking performance is linked to probe performance necessitates investigation into the design of tracking probes for proponents of marker-based tracking. The challenges involved with probe design include prediction of the accuracy and precision of a tracking probe, the creation of arbitrarily-shaped tracking probes, and the assessment of the newly created probes. To address these issues, we present a pioneer framework for designing conformal tracking probes. Conformal in this work means to adapt to the shape of the tracked objects and to the environmental constraints. As part of the framework, the accuracy in position and orientation of a given probe may be predicted given the system noise. The framework is a methodology for designing tracking probes based upon performance goals and environmental constraints. After presenting the conformal tracking framework, the elements used for completing the steps of the framework are discussed. We start with the application of optimization methods for determining the probe geometry. Two overall methods for mapping markers on tracking probes are presented, the Intermediary Algorithm and the Viewpoints Algorithm. Next, we examine the method used for pose estimation and present a mathematical model of error propagation used for predicting probe performance in pose estimation. The model uses a first-order error propagation, perturbing the simulated marker locations with Gaussian noise. The marker locations with error are then traced through the pose estimation process and the effects of the noise are analyzed. Moreover, the effects of changing the probe size or the number of markers are discussed. Finally, the conformal tracking framework is validated experimentally. The assessment methods are divided into simulation and post-fabrication methods. Under simulation, we discuss testing of the performance of each probe design. Then, post-fabrication assessment is performed, including accuracy measurements in orientation and position. The framework is validated with four tracking probes. The first probe is a six-marker planar probe. The predicted accuracy of the probe was 0.06 deg and the measured accuracy was 0.083 plus/minus 0.015 deg. The second probe was a pair of concentric, planar tracking probes mounted together. The smaller probe had a predicted accuracy of 0.206 deg and a measured accuracy of 0.282 plus/minus 0.03 deg. The larger probe had a predicted accuracy of 0.039 deg and a measured accuracy of 0.017 plus/minus 0.02 deg. The third tracking probe was a semi-spherical head tracking probe. The predicted accuracy in orientation and position was 0.54 plus/minus 0.24 deg and 0.24 plus/minus 0.1 mm, respectively. The experimental accuracy in orientation and position was 0.60 plus/minus 0.03 deg and 0.225 plus/minus 0.05 mm, respectively. The last probe was an integrated, head-mounted display probe, created using the conformal design process. The predicted accuracy of this probe was 0.032 plus/minus 0.02 degrees in orientation and 0.14 plus/minus 0.08 mm in position. The measured accuracy of the probe was 0.028 plus/minus 0.01 degrees in orientation and 0.11 plus/minus 0.01 mm in position. These results constitute an order of magnitude improvement over current marker-based tracking probes in orientation, indicating the benefits of a conformal tracking approach. Also, this result translates to a predicted positional overlay error of a virtual object presented at 1m of less than 0.5 mm, which is well above reported overlay performance in virtual environments.

<p>Upon introducing semi- and fully automated vehicles on the road, drivers will be reluctant to focus on the traffic interaction and rely on the vehicles' decision-making. However, encountering pedestrians still poses a significant difficulty for modern automated driving technologies. Considering the high-level complexity in human behavior modeling to solve a real-world problem, deep-learning algorithms trained from naturalistic data have become promising solutions. Nevertheless, although developing such algorithms is achievable based on scene data collection and driver knowledge extraction, evaluation remains challenging due to the potential crash risks and limitations in acquiring ground-truth intention changes. </p> <p><br></p> <p>This study proposes a VR-based testing bed to evaluate real-time pedestrian intention algorithms as VR simulators are recognized for their affordability and adaptability in producing a variety of traffic situations, and it is more reliable to conduct human-factor research in autonomous cars. The pedestrian wears the head-mounted headset or uses the keyboard input and makes decisions in accordance with the circumstances. The simulator has added a credible and robust experience, essential for exhibiting the real-time behavior of the pedestrian. While crossing the road, there exists uncertainty associated with pedestrian intention. Our simulator will anticipate the crossing intention with consideration of the ambiguity of the pedestrian behavior. The case study has been performed over multiple subjects in several crossing conditions based on day-to-day life activities. It can be inferred from the study outcomes that the pedestrian intention can be precisely inferred using this VR-based simulator. However, depending on the speed of the car and the distance between the vehicle and the pedestrian, the accuracy of the prediction can differ considerably in some cases.</p>

Night vision goggles (NVGs) are optical devices used to enhance human vision at low light conditions such as nighttime. The image seen through the goggles is brightened but with the consequence of introduced visual limitations and illusions. Because of this, fighter pilots need to undergo proper training with such equipment before operating with them in real-life. An NVG simulation within a Mixed Reality (MR) flight simulator can in theory be used to build the skills needed and directly translate them into real life. In this thesis, an NVG effect was added to a video see-through camera feed(VST) such that a whole NVG simulation could be experienced in an MR flight simulator. Furthermore, a method to seamlessly integrate the VST into the nocturnal virtual world was proposed. By conducting a semi structured interview with an NVG expert, the experienced realism, presence, and training value of the implemented effects were measured. A thematic analysis of the gathered interview data provided insight into the most important themes regarding NVG simulations within an MR flight simulator. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>