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Item Light Clustering for Dynamic Image Based Lighting(The Eurographics Association, 2012) Staton, Sam; Debattista, Kurt; Bashford-Rogers, Thomas; Chalmers, Alan; Hamish Carr and Silvester CzannerHigh Dynamic Range (HDR) imagery has made it possible to relight virtual objects accurately with the captured lighting. This technique, called Image Based Lighting (IBL), is a commonly used to render scenes using real-world illumination. IBL has mostly been limited to static scenes due to limitations of HDR capture. However, recently there has been progress on developing devices which can capture HDR video sequences. These can be also be used to light virtual environments dynamically. If existing IBL algorithms are applied to this dynamic problem, temporal artifacts viewed as flickering can often arise due to samples being selected from different parts of the environment in consecutive frames. In this paper we present a method for efficiently rendering virtual scenarios with such captured sequences based on spatial and temporal clustering. Our proposed Dynamic IBL (DIBL) method improves temporal quality by suppressing flickering, and we demonstrate the application to fast previews of scenes lit by video environment maps.Item A Calibrated Olfactory Display for High Fidelity Virtual Environments(The Eurographics Association, 2016) Dhokia, Amar; Doukakis, Efstratious; Asadipour, Ali; Harvey, Carlo; Bashford-Rogers, Thomas; Debattista, Kurt; Waterfield, Brian; Chalmers, Alan; Cagatay Turkay and Tao Ruan WanOlfactory displays provide a means to reproduce olfactory stimuli for use in virtual environments. Many of the designs produced by researchers, strive to provide stimuli quickly to users and focus on improving usability and portability, yet concentrate less on providing high levels of accuracy to improve the fidelity of odour delivery. This paper provides the guidance to build a reproducible and low cost olfactory display which is able to provide odours to users in a virtual environment at accurate concentration levels that are typical in everyday interactions; this includes ranges of concentration below parts per million and into parts per billion. This paper investigates build concerns of the olfactometer and its proper calibration in order to ensure concentration accuracy of the device. An analysis is provided on the recovery rates of a specific compound after excitation. This analysis provides insight into how this result can be generalisable to the recovery rates of any volatile organic compound, given knowledge of the specific vapour pressure of the compound.Item Selective BRDFs for High Fidelity Rendering(The Eurographics Association, 2016) Bradley, Tim; Debattista, Kurt; Bashford-Rogers, Thomas; Harvey, Carlo; Doukakis, Stratos; Chalmers, Alan; Cagatay Turkay and Tao Ruan WanHigh fidelity rendering systems rely on accurate material representations to produce a realistic visual appearance. However, these accurate models can be slow to evaluate. This work presents an approach for approximating these high accuracy reflectance models with faster, less complicated functions in regions of an image which possess low visual importance. A subjective rating experiment was conducted in which thirty participants were asked to assess the similarity of scenes rendered with low quality reflectance models, a high quality data-driven model and saliency based hybrids of those images. In two out of the three scenes that were evaluated significant differences were not found between the hybrid and reference images. This implies that in less visually salient regions of an image computational gains can be achieved by approximating computationally expensive materials with simpler analytic models.Item Visual Saliency for Smell Impulses and Application to Selective Rendering(The Eurographics Association, 2011) Harvey, Carlo; Bashford-Rogers, Thomas E. W.; Debattista, Kurt; Chalmers, Alan; Ian Grimstead and Hamish CarrA major challenge in generating high-fidelity virtual environments is to be able to provide interactive rates of realism. However this is very computationally demanding and only recently visual perception has been used in high-fidelity rendering to improve performance considerably by a series of novel exploitations; to render parts of the scene that are not currently being attended by the viewer at a much lower quality without the difference being perceived. This paper investigates the effect various smells have on the visual attention of the user when free viewing a set of engineered images. We verify the worth of investigating these saccade shifts (fast movements of the eyes) due to attention distraction to a congruent smell object. By analysing the gaze points, we identify time spent attending a particular area of a scene. We also present a technique from measured data to remodulate traditional saliency maps of image features to account for the observed results. We show that smell provides an impulse on attention to affect perception in such a way that this can be used to guide selective rendering of scenes through use of the remodulated saliency maps.Item Backwards Compatible JPEG Stereoscopic High Dynamic Range Imaging(The Eurographics Association, 2012) Selmanovic, Elmedin; Debattista, Kurt; Bashford-Rogers, Thomas; Chalmers, Alan; Hamish Carr and Silvester CzannerIn this paper we introduce Stereoscopic High Dynamic Range (SHDR) Imagery which is a novel tecnique that combines high dynamic range imaging and stereoscopy. Stereoscopic imaging captures two images representing the views of both eyes and allows for better depth perception. High dynamic range (HDR) imaging is an emerging technology which allows the capture, storage and display of real world lighting as opposed to traditional imagery which only captures a restricted range of light due to limitation in hardware capture and displays. HDR provides better contrast and more natural looking scenes. One of the main challenges that needs to be overcome for SHDR to be successful is an efficient storage format that compresses the very large sizes obtained by SHDR if left uncompressed; stereoscopic imaging requires the storage of two images and uncompressed HDR requires the storage of a floating point value per colour channel per pixel. In this paper we present a number of SHDR compression methods that are backward compatible with traditional JPEG, stereo JPEG and JPEG-HDR. The proposed methods can encode SHDR content to little more than that of a traditional LDR image and the backward compatibility property encourages early adopters to adopt the format since their content will still be viewable by any of the legacy viewers.Item Efficient Remote Rendering Using Equirectangular Projection(The Eurographics Association, 2017) McNamee, Josh; Debattista, Kurt; Chalmers, Alan; Tao Ruan Wan and Franck VidalPresenting high quality Virtual Reality (VR) experiences on head-mounted displays (HMDs) requires significant computational requirements. To ensure a high-fidelity experience, the displayed images must be highly accurate, detailed and respond with a very low latency. In order to achieve high-fidelity realistic experiences, advantage needs to be taken of remote high performance computing resources. This paper presents a novel method of streaming high-fidelity graphics content from a remote physically accurate renderer to an HMD. In particular, an equirectangular projection is transmitted from the cloud to a client, so that latency-free 360° observations can be made within a viewpoint.Item Fast Scalable k-NN Computation for Very Large Point Clouds(The Eurographics Association, 2012) Spina, Sandro; Debattista, Kurt; Bugeja, Keith; Chalmers, Alan; Hamish Carr and Silvester CzannerThe process of reconstructing virtual representations of large real-world sites is traditionally carried out through the use of laser scanning technology. Recent advances in these technologies led to improvements in precision and accuracy and higher sampling rates. State of the art laser scanners are capable of acquiring around a million points per second, generating enormous point cloud data sets. These data sets are usually cleaned through the application of numerous post-processing algorithms, like normal determination, clustering and noise removal. A common factor in these algorithms is the recurring need for the computation of point neighborhoods, usually by applying algorithms to compute the k-nearest neighbours of each point. The majority of these algorithms work under the assumption that the data sets operated on can fit in main memory, while others take into account the size of the data sets and are thus designed to keep data on disk. We present a hybrid approach which exploits the spatial locality of point clusters in the point cloud and loads them in system memory on demand by taking advantage of paged virtual memory in modern operating systems. In this way, we maximize processor utilization while keeping I/O overheads to a minimum. We evaluate our approach on point cloud sizes ranging from 50K to 333M points on machines with 1GB, 2GB, 4GB and 8GB of system memory.Item Exploring Face Recognition under Complex Lighting Conditions with HDR Imaging(The Eurographics Association, 2016) Ige, Emmanuel O.; Debattista, Kurt; Muhkerjee, Ratnajit; Chalmers, Alan; Cagatay Turkay and Tao Ruan WanApplying image processing applications under complex or harsh lighting conditions can be a difficult challenge. In particular, face recognition can be prone to such limitations due to the uncontrolled nature of the applications to which it is applied. One of the conventional ways used to resolve this concern is by capturing images under controlled light or pre-processing the affected images, which can change the perception of the resultant images. One of the primary issues with this is the lack of information present in the original images due to over-exposed and under-exposed pixels. High Dynamic Range (HDR) imaging offers an alternative due to its capability of handling natural lighting. This paper explores the use HDR imaging for face recognition. A training and testing set of HDR images under different harsh lighting conditions was created. Traditional low dynamic range methods were compared with using the full range and applying HDR methods to a traditional face recognition method. Results demonstrate that adapting HDR captured images for use with traditional face recognition methods via a tone mapping provides sufficient improvement and enables traditional algorithms to cope well with harsh lighting scenarios.Item Acquisition, Representation and Rendering of Real-World Models using Polynomial Texture Maps in 3D(The Eurographics Association, 2013) Vassallo, Elaine; Spina, Sandro; Debattista, Kurt; Silvester Czanner and Wen TangThe ability to represent real-world objects digitally in a realistic manner is an indispensable tool for many applications. This paper proposes a method for acquiring, processing, representing, and rendering these digital representations. Acquisition can be divided into two processes: acquiring the 3D geometry of the object, and obtaining the texture and reflectance behaviour of the object. Our work explores the possibility of using Microsoft's Kinect sensor to acquire the 3D geometry, by registration of data captured from different viewpoints. The Kinect sensor itself is used to acquire texture and reflectance information which is represented using multiple Polynomial Texture Maps. We present processing pipelines for both geometry and texture, and finally our work examines how the acquired and processed geometry, texture, and reflectance behaviour information can be mapped together in 3D, allowing the user to view the object from different viewpoints while being able to interactively change light direction. Varying light direction uncovers details of the object which would not have been possible to observe using a single, fixed, light direction. This is useful in many scenarios, amongst which is the examination of cultural heritage artifacts with surface variations.Item The Effect of Discretised and Fully Converged Spatialised Sound on Directional Attention and Distraction(The Eurographics Association, 2010) Harvey, Carlo; Walker, Steve; Bashford-Rogers, Thomas; Debattista, Kurt; Chalmers, Alan; John Collomosse and Ian GrimsteadA major challenge in Virtual Reality (VR) is to be able to provide interactive rates of realism. However this is very computationally demanding and only recently has high-fidelity rendering become close to interactive rates through a series of novel exploitations of visual perception; to render parts of the scene that are not currently being attended by the viewer at a much lower quality without the difference being perceived. This paper investigates the effect spatialised directional sounds, both discrete and converged have on the visual attention of the user with and without an auditory cue present in the scene. We verify the worth of investigating subliminal saccade shifts from directional audio impulses via a pilot study to eye track participant's free viewing a scene with an audio impulse and an acoustic identifier and also with an audio impulse and no acoustic identifier versus a control. By selecting look zones, we can identify how long users are spending attending a particular area of a scene in these scenarios. This work also investigates whether the effect prevailed, and if so to what extent, with discretised spatialised sound as opposed to a fully converged audio sample. We also present a novel technique for generating interactive discrete acoustic samples from arbitrary geometry. We show that even without an acoustic identifier in the scene, directional sound provides enough of an impulse to guide subliminal saccade shifts and affect perception in such a way that this can be used to guide selective rendering of the scenes.