[diss] Perustieteiden korkeakoulu / SCI

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Crisp, fuzzy, and probabilistic faceted semantic search
(Aalto-yliopiston teknillinen korkeakoulu, 2010) Holi, Markus; Hyvönen, Eero, Prof.; Mediatekniikan laitos; Department of Media Technology; Aalto-yliopiston teknillinen korkeakoulu; Hyvönen, Eero, Prof.
This dissertation presents contributions to the development of the faceted semantic search (FSS) paradigm. First, two fundamental solutions to FSS, which have been widely used since their development are presented. The first is the projection of search facets from annotation ontologies using logical rules. The second is the logic rule-based generation of recommendation links for search items based on the semantic relations of these items. After presenting these solutions, the rest of the dissertation focuses on solving the following deficiencies of FSS: the lack of capabilities to model uncertainty, the inability to rank search results according to relevance, and the usability problems resulting from naively using annotation ontology concepts as search categories. Two sets of solutions to these problems are presented. First, a fuzzy faceted semantic search (FFSS) framework is developed, which extends the crisp set basis of FSS to fuzzy sets. This framework is based on two main ingredients: First, weighted annotations, which are used to determine the membership degrees of search items in annotation concepts. Second, fuzzy mappings of separate end-user categories onto the annotation concepts. In addition, also a probabilistic faceted semantic search (PFSS) framework was developed, which incorporates weighted annotations, modeling of uncertainty in Semantic Web taxonomies, sophisticated mappings of end-user facets onto annotation ontologies, and the combination of evidence from multiple ranking schemes. These ranking methods were empirically analyzed. According to the preliminary evaluation both ranking methods significantly improve quality of search results compared to crisp FSS. Both also outperformed a currently used heuristical ranking method. However, in the case of FFSS this difference did not reach the level of statistical significance.
Depth Perception of Augmented and Natural Scenes through Stereoscopic Systems
(Aalto University, 2014) Kytö, Mikko; Häkkinen, Jukka, Dr., Aalto University, Department of Media Technology, Finland; Mediatekniikan laitos; Department of Media Technology; Visual Media Research Group; Visuaalisen median tutkimusryhmä; Perustieteiden korkeakoulu; School of Science; Oittinen, Pirkko, Prof., Aalto University, Department of Media Technology, Finland
The ability to perceive the world with two eyes is called stereoscopic perception. The slightly different viewing positions of the two eyes provide three-dimensional information about their overlapping field of view. To utilize this common human ability technologically, stereoscopic three-dimensional (S3D) systems, for both imaging the real world with cameras and visualization in displays, need to be designed and developed. However, there is limited quantitative knowledge regarding visual performance and viewing experience, and more information is needed to better define the requirements for S3D systems. The overall research question of the dissertation addresses the benefits of stereoscopic functionality and its incorporation into guidelines for the design of stereoscopic systems. In this dissertation, human depth perception through S3D systems is evaluated based on performance measures and viewing experience attributes. Typically, depth perception through S3D systems is investigated at distances that are within arm's reach; however, we focus primarily on distances from 2 m to 30 m away from the observer, which is called action space. Within the action space, we study the depth perception in augmented reality (AR) and natural scenes. In the visual AR applications, the observer sees virtual objects that are aligned with the surrounding 3D reality in real time. Two types of AR scenes are investigated: augmented objects above the ground plane and behind the wall. For both AR scene types, the added performance of stereoscopic viewing was examined and a novel visualization approach was conceptualized and tested. In the case of natural scenes, the stereoscopic perception was investigated with crowds and typical mobile imaging. In the crowds scene type, we studied the discrimination accuracy in a head counting task. In typical indoor imaging scene types, the viewing experience was evaluated by varying the camera separation. All the experiments were conducted in set-ups constructed from software and hardware components. The results of the experiments indicate that the benefits of stereoscopic viewing are significant within the chosen scene types. The dissertation contributes three key results that are applicable to stereoscopic systems: 1) a novel visualization approach for augmented reality that involves adding virtual reference objects to the scene; 2) quantifying the performance of stereoscopic perception within the action space for virtual objects that lie above the ground plane or behind the wall and for perceiving crowds; and 3) identifying the effect of the camera separation range on the experience of viewing stereoscopic photographs.
Efficient physics-based room-acoustics modeling and auralization
(Aalto-yliopiston teknillinen korkeakoulu, 2010) Siltanen, Samuel; Lokki, Tapio, Dr.; Mediatekniikan laitos; Department of Media Technology; Aalto-yliopiston teknillinen korkeakoulu; Savioja, Lauri, Prof.
The goal of this research is to develop efficient algorithms for physics-based room acoustics modeling and real-time auralization. Given the room geometry and wall materials, in addition to listener and sound source positions and other properties, the auralization system aims at reproducing the sound as would be heard by the listener in a corresponding physical setup. A secondary goal is to predict the room acoustics parameters reliably. The thesis presents a new algorithm for room acoustics modeling. The acoustic radiance transfer method is an element-based algorithm which models the energy transfer in the room like the acoustic radiosity technique, but is capable of modeling arbitrary local reflections defined as bidirectional reflectance distribution functions. Implementing real-time auralization requires efficient room acoustics modeling. This thesis presents three approaches for improving the speed of the modeling process. First, the room geometry can be reduced. For this purpose an algorithm, based on volumetric decomposition and reconstructions of the surface, is described. The algorithm is capable of simplifying the topology of the model and it is shown that the acoustical properties of the room are sufficiently well preserved with even 80 % reduction rates in typical room models. Second, some of the data required for room acoustics modeling can be precomputed. It is shown that in the beam tracing algorithm a visibility structure called "beam tree" can be precomputed efficiently, allowing even moving sound sources in simple cases. In the acoustic radiance transfer method, effects of the room geometry can be precomputed. Third, the run-time computation can be optimized. The thesis describes two optimization techniques for the beam tracing algorithm which are shown to speed up the process by two orders of magnitude. On the other hand, performing the precomputation for the acoustic radiance transfer method in the frequency domain allows a very efficient implementation of the final phase of the modeling on the graphics processing unit. An interactive auralization system, based on this technique is presented.
Enabling technologies for audio augmented reality systems
(Aalto University, 2014) Gamper, Hannes; Lokki, Tapio, Assoc. prof., Aalto University, Department of Media Technology, Finland; Puolamäki, Kai, Dr., Aalto University, Department of Information and Computer Science, Finland; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; School of Science; Savioja, Lauri, Prof., Aalto University, Department of Media Technology, Finland
Audio augmented reality (AAR) refers to technology that embeds computer-generated auditory content into a user's real acoustic environment. An AAR system has specific requirements that set it apart from regular human--computer interfaces: an audio playback system to allow the simultaneous perception of real and virtual sounds; motion tracking to enable interactivity and location-awareness; the design and implementation of auditory display to deliver AAR content; and spatial rendering to display spatialised AAR content. This thesis presents a series of studies on enabling technologies to meet these requirements. A binaural headset with integrated microphones is assumed as the audio playback system, as it allows mobility and precise control over the ear input signals. Here, user position and orientation tracking methods are proposed that rely on speech signals recorded at the binaural headset microphones. To evaluate the proposed methods, the head orientations and positions of three conferees engaged in a discussion were tracked. The binaural microphones improved tracking performance substantially. The proposed methods are applicable to acoustic tracking with other forms of user-worn microphones. Results from a listening test investigating the effect of auditory display parameters on user performance are reported. The parameters studied were derived from the design choices to be made when implementing auditory display. The results indicate that users are able to detect a sound sample among distractors and estimate sample numerosity accurately with both speech and non-speech audio, if the samples are presented with adequate temporal separation. Whether or not samples were separated spatially had no effect on user performance. However, with spatially separated samples, users were able to detect a sample among distractors and simultaneously localise it. The results of this study are applicable to a variety of AAR applications that require conveying sample presence or numerosity. Spatial rendering is commonly implemented by convolving virtual sounds with head-related transfer functions (HRTFs). Here, a framework is proposed that interpolates HRTFs measured at arbitrary directions and distances. The framework employs Delaunay triangulation to group HRTFs into subsets suitable for interpolation and barycentric coordinates as interpolation weights. The proposed interpolation framework allows the realtime rendering of virtual sources in the near-field via HRTFs measured at various distances.
Human abilities to perceive, understand, and manage multi-dimensional information with visualizations
(Aalto University, 2012) Berg, Mikko; Kojo, Ilpo; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; School of Science; Takala, Tapio, Prof.
Visualizations facilitate presenting information in a form adapted to human visual system. The thesis defines this adapting more precisely with a framework of human-visualization interaction. Human capacity limits are used to identify critical subtasks in interaction that specify whether the data quantities and complexity of relations are understandable. In reality, use context and personal characteristics also impact understanding. The framework identifies commonalities of human processing in context of large quantities of multi-dimensional data. The novel extension is to identify multi-dimensionality from tasks of ordinary people, such as shopping or voting. According to the hypothesis ordinary people can also understand more complex information with the help of visualized dimension-reduction algorithms (e.g., MDS or SOM). Such context and haste give prominence to perceptual and cognitive processes, the critical subtasks, and the related visual parameters. Unfortunately, the interactive effects of the related parameters on performance cannot be predicted with real applications, and thus applied studies are needed. The proposed multi-disciplinary framework is based on reviewing empirical findings about humans. First, cognitive science about human concept formation is used to provide indications about how to pre-processes data into more readily understandable form. Second, vision research, experimental psychology, and neuroscience are used to explain the interaction, when information is received through vision and the input is influenced through gaze shifts and manual operations. Third, findings are reviewed about conditions, in which processing is likely to be externalized to visualization or tool as opposed to being performed by human mind. The framework is then applied for psychophysically controlled reaction time and eye movement experiments based on selective review of methods and critical visual parameters in research of visual searching. The evaluated tasks, searching and integrating, were chosen based on both behavioral studies with visualizations and implications of the framework. The ordinary people interacting with visualizations were evaluated indirectly from the popularity, feedback, and observations during two Finnish elections. The framework led to three suggested principles. First, externalizing memory tasks and information processing to visualizations reduces mental load. Second, relations of dimensions can be uncovered by perceiving consequences of own manual actions. Third, peripheral vision is suitable for representing coarse outlines, for instance depicting dimension reduction. Facilitating rapid gaze shifts is important for all of these principles.
Interaction with eyes-free and gestural interfaces
(Aalto University, 2013) Kajastila, Raine; Lokki, Tapio, Associate Prof., Aalto University, Finland; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; School of Science; Lokki, Tapio, Associate Prof., Aalto University, Finland
Eyes-free interaction aims to control devices without the need to look at them. This is especially useful while driving, walking on a bustling street, or in other situations when looking at a display would be dangerous, inconvenient or restricted. Hand gestures and feedback with sound offer an eyes-free alternative to visual displays, and this thesis studies using them with devices and the surrounding environment. In this thesis work, advanced circular auditory menus and three parallel control methods for using them were developed. Essentially, the thesis work concentrated on a circular interaction metaphor in auditory menus, in which the gesture was mapped directly to the position in the menu. The introduced control methods and auditory menu properties were tested with user experiments, and a mobile application integrating auditory and visual menus was built. The three gestural control methods to control circular auditory menus included accelerometer-based, touch screen-based, and camera-based interaction. All control methods were proven accurate and fast enough for efficient eyes-free use. Additionally, the same control methods were used in both visual and auditory domains, which facilitates switching to eyes-free use when needed and may also improve the accessibility of the interface for visually impaired users. Results of user experiments showed that the introduced visual and auditory menu design was easy and intuitive to learn without extensive training. Furthermore, a solution for eyes-free access to large menus was proposed, and user experiments indicated that dynamic menu item placement is efficient, accurate, and allowed the use of large menus. This thesis also investigated the use of auditory displays and gesture interfaces in performing arts. The perceived shape and size of a space can be changed by applying different reverberation times in different directions using multiple reverberation systems. Implementing a reverberation system and a test setup for subjective evaluation validated this. The implemented reverberation system has been utilized in live opera performances and to enhance lecture room acoustics. The use of gesture control is explored in an experimental opera production in which the performers controlled an audiovisual virtual stage live. The live interaction was useful when user controlled media was directly mapped onto gestures and when detailed nuances of movement were hard for a technician controlling the media to follow.
Journalistic image access : description, categorization and searching
(Aalto University, 2011) Westman, Stina; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; Oittinen, Pirkko, Prof.
The quantity of digital imagery continues to grow, creating a pressing need to develop efficient methods for organizing and retrieving images. Knowledge on user behavior in image description and search is required for creating effective and satisfying searching experiences. The nature of visual information and journalistic images creates challenges in representing and matching images with user needs. The goal of this dissertation was to understand the processes in journalistic image access (description, categorization, and searching), and the effects of contextual factors on preferred access points. These were studied using multiple data collection and analysis methods across several studies. Image attributes used to describe journalistic imagery were analyzed based on description tasks and compared to a typology developed through a meta-analysis of literature on image attributes. Journalistic image search processes and query types were analyzed through a field study and multimodal image retrieval experiment. Image categorization was studied via sorting experiments leading to a categorization model. Advances to research methods concerning search tasks and categorization procedures were implemented. Contextual effects on image access were found related to organizational contexts, work, and search tasks, as well as publication context. Image retrieval in a journalistic work context was contextual at the level of image needs and search process. While text queries, together with browsing, remained the key access mode to journalistic imagery, participants also used visual access modes in the experiment, constructing multimodal queries. Assigned search task type and searcher expertise had an effect on query modes utilized. Journalistic images were mostly described and queried for on the semantic level but also syntactic attributes were used. Constraining the description led to more abstract descriptions. Image similarity was evaluated mainly based on generic semantics. However, functionally oriented categories were also constructed, especially by domain experts. Availability of page context promoted thematic rather than object-based categorization. The findings increase our understanding of user behavior in image description, categorization, and searching, as well as have implications for future solutions in journalistic image access. The contexts of image production, use, and search merit more interest in research as these could be leveraged for supporting annotation and retrieval. Multiple access points should be created for journalistic images based on image content and function. Support for multimodal query formulation should also be offered. The contributions of this dissertation may be used to create evaluation criteria for journalistic image access systems.
Localization and tracing of early acoustic reflections in enclosures
(Aalto University, 2011) Tervo, Sakari; Lokki, Tapio, Adj. Prof.; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; Savioja, Lauri, Prof.
Objective room acoustic studies are conducted by measuring room impulse responses. The standard techniques include the use of an omni-directional source and, in most cases, one omni-directional microphone. This approach is well defined when measuring the standard room acoustic parameters. Recently, early reflections, the first arriving sound waves in the room impulse response after the direct sound, have gained attention in research. The spatial location of the early reflections, i.e., the location of the image-source, can be used in room acoustic studies, auralization, room geometry inference, and in-situ measurement of acoustic properties of surfaces from room impulse responses. The location, however, cannot be obtained from the standard room impulse response measurement. Therefore, special microphone array techniques have been used for spatial analysis of room impulse responses. This thesis studies the localization of early reflections. Firstly, a measurement technique of room impulse responses with directional loudspeakers is proposed. This allows better spatial and temporal separability between the reflections than the standard omni-directional loudspeaker. Secondly, the use of microphone array techniques on the localization of early reflections is studied. Several techniques used in other localization tasks are transformed and applied for the localization of early reflections. In detail, the combination of time of arrival and time difference of arrival is researched. Moreover, interpolation of the time difference of arrival estimation function is proposed. The use of sound intensity vector based localization is also considered. Finally, novel ad-hoc localization techniques for early reflections are proposed. Results for theoretical, simulation, and real data experiments are presented.
Methods and applications for ontology-based recommender systems
(Aalto-yliopiston teknillinen korkeakoulu, 2010) Ruotsalo, Tuukka; Hyvönen, Eero, Prof.; Mediatekniikan laitos; Department of Media Technology; Aalto-yliopiston teknillinen korkeakoulu; Hyvönen, Eero, Prof.
Recommender systems are a specific type of information filtering systems used to identify a set of objects that are relevant to a user. Instead of a user actively searching for information, recommender systems provide advice to users about objects they might wish to examine. Content-based recommender systems deal with problems related to analyzing the content, making heterogeneous content interoperable, and retrieving relevant content for the user. This thesis explores ontology-based methods to reduce these problems and to evaluate the applicability of the methods in recommender systems. First, the content analysis is improved by developing an automatic annotation method that produces structured ontology-based annotations from text. Second, an event-based method is developed to enable interoperability of heterogeneous content representations. Third, methods for semantic content retrieval are developed to determine relevant objects for the user. The methods are implemented as part of recommender systems in two cultural heritage information systems: CULTURESAMPO and SMARTMUSEUM. The performance of the methods were evaluated through user studies. The results can be divided into five parts. First, the results show improvement in automatic content analysis compared to state of the art methods and achieve performance close to human annotators. Second, the results show that the event-based method developed is suitable for bridging heterogeneous content representations. Third, the retrieval methods show accurate performance compared to user opinions. Fourth, semantic distance measures are compared to study the best query expansion strategy. Finally, practical solutions are developed to enable user profiling and result clustering. The results show that ontology-based methods enable interoperability of heterogeneous knowledge representations and result in accurate recommendations. The deployment of the methods to practical recommender systems show applicability of the results in real life settings.
Methods for Building Semantic Portals
(Aalto University, 2013) Suominen, Osma; Mediatekniikan laitos; Department of Media Technology; Semantic Computing Research Group; Semanttisen laskennan tutkimusryhmä; Perustieteiden korkeakoulu; School of Science; Hyvönen, Eero, Prof., Aalto University, Department of Media Technology, Finland
Semantic portals are information systems which collect information from several sources and combine them using semantic web technologies into a user interface that solves information needs of users. Creating such portals requires methods and tools from multiple disciplines, including knowledge representation, information retrieval, information extraction, and user interface design. This thesis explores methods for building and improving semantic portals and other semantic web applications with contributions in three areas. The studies included in the thesis draw from the design science methodology in information systems research. First, a method for creating of faceted search user interfaces for semantic portals utilizing controlled vocabularies with a complex hierarchical structure is presented. The results show that the method allows the creation of user-centric search facets that hide the complex hierarchies from the user, resulting in a user-friendly faceted search interface. Second, the creation of structured metadata from text documents is enhanced by adapting a state of the art automatic subject indexing system to Finnish language texts. The results show that using a suitable combination of existing tools, automatic subject indexing quality comparable to that of human indexers can be attained in a highly inflected language such as Finnish. Finally, the quality of controlled vocabularies such as thesauri and lightweight ontologies is examined by developing a set of quality criteria for vocabularies expressed using the SKOS standard, and methods for correcting structural problems in SKOS vocabularies are presented. The results show that most published SKOS vocabularies suffer from quality issues and violate the SKOS integrity conditions. However, the great majority of such problems were corrected by the methods presented in this dissertation. The methods have been implemented in several real world applications, including the HealthFinland health information portal, the ARPA information extraction toolkit, and the ONKI ontology library system.
Methods for creating and using geospatio-temporal semantic web
(Aalto-yliopiston teknillinen korkeakoulu, 2010) Kauppinen, Tomi; Mediatekniikan laitos; Department of Media Technology; Aalto-yliopiston teknillinen korkeakoulu; Hyvönen, Eero, Prof.
This dissertation discusses the problems and the methods of creating and using ontologies in the area of digital cultural heritage. One of the problems is that content annotations in semantic cultural heritage portals commonly make spatiotemporal references to historical regions and places using names whose meanings are different in different times. For example, historical administrational regions such as countries, municipalities, and cities have been renamed, merged together, split into parts, and annexed or moved to and from other regions. The contribution of this dissertation to this problem is to develop methods which can be used to model, produce and utilize geospatio-temporal ontologies. The resources in geospatio-temporal ontologies can be used as annotation terms for describing content, and also for seeking information. The main point of this dissertation is to describe schemas, models and methods that produce and utilize a geospatio-temporal ontology. The schemas and the models are used as inputs for the methods. These methods generate identifiers for spatio-temporal instances, and also relationships between them. In this work, historical Finnish municipalities were modeled and geospatio-temporal descriptions for them created from a filled-up schema. Methods enriched the models by creating geospatio-temporal relationships between these temporal municipalities. The resulting collection of models are referred to as the Finnish Spatio-temporal Ontology (Suomen ajallinen paikkaontologia, SAPO). Specific relationships of the geo-spatiotemporal instances provided the basis for novel recommendation, data mining and visualization schemes. The results of the experiments were promising. For example, with the help of the ontology a user has the ability to retrieve also the content annotated to a historic region even if she searches using a contemporary name of the same or partially overlapping region. The work contributes also to modeling and reasoning about imprecise temporal intervals. A set of different measures based on analyzing two fuzzy temporal intervals are presented and evaluated in the work. The use of a combination of different measures for calculating relevance between temporal intervals was found out to perform best.
Navigation and Object Manipulation in Collaborative VR Interior Design
(Aalto University, 2012) Laakso, Mikko; Savioja, Lauri, Prof., Aalto University, Finland; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; School of Science; Takala, Tapio, Prof., Aalto University, Finland
Virtual reality (VR) is a technologically created, immersive and interactive space. Interior design is an important profession where creative and technical solutions are applied to achieve a built environment. VR could be very beneficial in that area, but unfortunately most current solutions are just for viewing purposes. The main research question in this thesis is to find out how to create a simple immersive VR interior design system using a collaborative model? The problem is approached via constructive research method; a thorough literature survey along with the design, implementation and evaluation of a new immersive design system called VIDS. Creating VIDS requires studying both navigation and design elements. Three experiments with 16 users are conducted to evaluate different users’ navigation abilities with different tools. For designer user interface, VIDS uses collaborative design model with Wizard of Oz –type collaborative input. The user moves around the model inside the virtual room and makes design requests to the wizard, who is outside on a nearby computer and handles the actual model update. To determine how well immersive interior design can be performed using VIDS, 24 test subjects participate in a kitchen furnishing experiment. The experiment results show that VIDS and collaborative design approach seem to be very effective. The most important strengths are that it allows free movement, real-size view of the space and fast editing. It also promotes better space utilization, encourages practical collaboration and ensures that the working environment is always under total control. Weaknesses include the export/import delay caused by the chosen synchronization solution and the catalogue system that should be improved. Attributes of a practical immersive VR interior design system can be summarized. The system a) should provide the user with a realistic first-person perspective of the environment, b) should be embedded with an ergonomic, quick and practical way to move, c) should include some possibility to collaborate (e.g., simple tasks for user, complicated for the wizard), d) possible pre-defined catalogue should preferably be merged into the software and e) all design modifications should be visible to the user as soon as possible.
Reduced-reference methods for measuring quality attributes of natural images in imaging systems
(Aalto University, 2012) Nuutinen, Mikko; Mediatekniikan laitos; Department of Media Technology; Visual Media Research Group; Perustieteiden korkeakoulu; School of Science; Oittinen, Pirkko, Prof., Aalto University, Finland
The main goal of the research field of image quality is to create a computational model capable of predicting the subjective visual quality of natural images and video. The model can be an alternative for expensive quality evaluations by human assessors. This dissertation aligns with this research field in the case of imaging systems, such as cameras, displays and printers. The traditional approach to measuring the quality of imaging systems is based on test targets. These targets primarily facilitate description of the performance of a system in terms of how it reproduces and distorts simple test signals rather than measure the visual quality of natural images captured or shown by an imaging system. This dissertation primarily contributes novel methods and algorithms for measuring the image quality attributes of natural images captured by cameras or printed by a printer. Both methods utilize reference image data in the reduced-reference mode. The method and algorithms developed for printers transform the printed natural test images into the form of the reference image by using a high-quality reference camera and multiple exposures. The methods and algorithms developed for camera images use a reference camera to capture scene information. The scene information is used to help measure the attributes of natural images. The main problem which needed to be solved concerns localization of areas in images from which different attributes can be measured. The challenge arises from a multidimensional distortion space in capture and display. The solution relies on low-level computational understanding of images. The methods were evaluated with subjective data. Compared with the state-of-the-art computational or test target metrics, these methods were highly effective at predicting the quality attributes of natural images captured by different cameras or printed on different papers. According to the results, the proposed methods can replace test target methods and even small-scale subjective tests in some situations.
View-based user interfaces for the Semantic Web
(Aalto-yliopiston teknillinen korkeakoulu, 2010) Mäkelä, Eetu; Hyvönen, Eero, Prof.; Mediatekniikan laitos; Department of Media Technology; Aalto-yliopiston teknillinen korkeakoulu; Hyvönen, Eero, Prof.
This thesis explores the possibilities of using the view-based search paradigm to create intelligent user interfaces on the Semantic Web. After surveying several semantic search techniques, the view-based search paradigm is explained, and argued to fit in a valuable niche in the field. To test the argument, numerous portals with different user interfaces and data were built using the paradigm. Based on the results of these experiments, this thesis argues that the paradigm provides a strong, extensible and flexible base on which to built semantic user interfaces. Designing the actual systems to be as adaptable as possible is also discussed.
A virtual symphony orchestra for studies on concert hall acoustics
(Aalto University, 2011) Pätynen, Jukka; Lokki, Tapio, Adj. Prof.; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; Savioja, Lauri, Prof.
Traditionally, concert hall acoustics is evaluated by listening to live concerts, which makes a direct comparison challenging. This thesis presents new tools and methods in the domain of the room acoustics evaluation, studies, and auralization. Auralization stands for the process of rendering an existing or modeled acoustic space in a way that it can be presented to the listener as he/she was listening to a sound inside the space under study. An essential topic in this thesis is a framework for studying room acoustics with a wide-area loudspeaker array. The proposed loudspeaker orchestra consists of a number of loudspeakers that are positioned in the shape resembling a symphony orchestra on a stage. The acoustics can be evaluated in-situ by playing back anechoic signals, or in laboratory conditions via convolution of the impulse responses measured from the loudspeaker orchestra. The presented method enables a direct comparison of concert halls and it has been successfully applied in practice in several research articles. The principal requirement for such a loudspeaker orchestra is anechoic signals of high quality. For this purpose, a method and implementation of a system for recording the symphony orchestra instruments individually is presented. As the result, a selection of anechoic orchestral music is obtained with perfect channel separation. The recordings, intended for advancing the research on acoustics and auralization, are published for academic use. Directivity of the orchestra instruments in performance situation is investigated with anechoic measurements. The results for different instruments can be compared against each other or applied directly into auralizations. Data from the directivity measurements is also applied in the objective analysis of the presented loudspeaker orchestra. Furthermore, the implemented measurement system is utilized in investigating the sound radiation of the balloons, which are often used in room acoustic measurements. Related to the anechoic recordings, a novel approach to creating an impression of a group of musicians from a single recorded player is proposed. The method is mainly based on the video and audio analysis of the temporal differences between orchestra string players. The method is particularly beneficial with the anechoic recordings, where recording an instrument section is not possible, and recording a large number of musicians individually is time-consuming. The listening test results show that the presented method provides a plausible simulation of an instrument section sound in comparison to an industry-standard method.
Web application user interface technologies
(Aalto University, 2011) Pohja, Mikko; Vuorimaa, Petri, Prof.; Mediatekniikan laitos; Department of Media Technology; Perustieteiden korkeakoulu; Vuorimaa, Petri, Prof.
The World Wide Web has expanded from a huge information storage repository into a worldwide application platform. Web applications have several benefits compared to desktop applications. An application can be used anywhere from any system and device, which means that only one version is needed, they do not need to be installed and developers can modify running applications. Despite all the benefits of the Web, web applications are suffering because they are developed using the same technologies as the static documents on the Web. Some of these web technologies are outdated and were not originally designed for the complex use cases of the modern applications to which they are now applied. For instance, HTML forms comprise the main interaction of an application, despite not having been designed to describe complex and interactive UIs. Another example is HTTP communication on the Web, which always requires client initiative and is too restrictive for dynamic web applications. Additionally, new usage contexts have brought with them new requirements for web applications, which are no longer used only via Graphical User Interfaces. Recently, several parties have developed specialized technologies for web application development. These solutions are not only minor additions to the existing technologies, but also new technologies. The goal of this thesis is to analyze the advanced web technologies and propose improvements to the technologies and architecture where applicable. The technologies are evaluated against a large set of requirements. The aim of the evaluation is two-fold. The first part is to select a technology on which to base the further improvements, and the second is to identify the deficiencies of the current solutions. The improvements focus on the developers' point-of-view. Based on the evaluation, this thesis proposes certain improvements related to multimodal interaction, server push, and remote UI updates. It also discusses software that supports the improvements and XML-based web technologies. Finally, the improvements are evaluated against the requirements and compared to other solutions.

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