International audienceHow do people appropriate their virtual hand representation when interacting in virtual environments? In order to answer this question , we conducted an experiment studying the sense of embodiment when interacting with three different virtual hand representations , each one providing a different degree of visual realism but keeping the same control mechanism. The main experimental task was a Pick-and-Place task in which participants had to grasp a virtual cube and place it to an indicated position while avoiding an obstacle (brick, barbed wire or fire). An additional task was considered in which participants had to perform a potentially dangerous operation towards their virtual hand: place their virtual hand close to a virtual spinning saw. Both qualitative measures and questionnaire data were gathered in order to assess the sense of agency and ownership towards each virtual hand. Results show that the sense of agency is stronger for less realistic virtual hands which also provide less mismatch between the participant's actions and the animation of the virtual hand. In contrast, the sense of ownership is increased for the human virtual hand which provides a direct mapping between the degrees of freedom of the real and virtual hand
A high performance biometric signal and image processing method to reveal blood perfusion towards 3D oxygen saturation mapping ABSTRACTNon-contact imaging photoplethysmography (PPG) is a recent development in the field of physiological data acquisition, currently undergoing a large amount of research to characterize and define the range of its capabilities. Contact-based PPG techniques have been broadly used in clinical scenarios for a number of years to obtain direct information about the degree of oxygen saturation for patients. With the advent of imaging techniques, there is strong potential to enable access to additional information such as multi-dimensional blood perfusion and saturation mapping. The further development of effective opto-physiological monitoring techniques is dependent upon novel modelling techniques coupled with improved sensor design and effective signal processing methodologies. The biometric signal and imaging processing platform (bSIPP) provides a comprehensive set of features for extraction and analysis of recorded iPPG data, enabling direct comparison with other biomedical diagnostic tools such as ECG and EEG. Additionally, utilizing information about the nature of tissue structure has enabled the generation of an engineering model describing the behaviour of light during its travel through the biological tissue. This enables the estimation of the relative oxygen saturation and blood perfusion in different layers of the tissue to be calculated, which has the potential to be a useful diagnostic tool.Keywords: imaging photoplethysmography, pulse oximetry, oxygen saturation mapping, signal acquisition and processing. *S.Hu@lboro.ac.uk; phone +44 1509 227059 INTRODUCTIONImaging photoplethysmography (iPPG) is one of the emerging medical imaging technologies to visualize peripheral blood perfusion in a specific tissue. Different from other optical related technologies, i.e., laser Doppler [1, 2] and Speckle imaging [3], iPPG aims to detect the dynamic change of blood volume in a designated tissue area rather than blood velocity and flow. Besides, iPPG can provide other human vital bioinformatics such as heart rate variability (HRV) [4] and pulse transit time (PTT) [5]. iPPG has significant priority over to the conventional PPG, as removes the primary limitations of spot measurement and contact sensory. iPPG can also monitor these vital human signs on different parts of skin surface simultaneously and bring the possible new insights that might come from hemodynamic mapping even 3D oxygen saturation in the tissue segments.Non-contact camera based iPPG has been well established with the visualization of blood perfusion [6], which demonstrated the simultaneous capture of PPG waveforms from the extremities at three wavelengths (660 nm, 840 nm and 905 nm) in both transmission and reflection modes. Another work has reported a reflection mode capture of 'heart cycle-related' pulsatile variations using a CMOS camera [7], with its illumination at 660 nm, 810 nm, and 940 nm. An additional research s...
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