arXiv subjects

Sakar Khattar

Publications and source records attributed to Sakar Khattar.

4 recordsLinked to original sources

arXiv2026

Passthrough Rigidity: The Behavioral and Visuomotor Costs of Mediated Perception

Broad public adoption of head-mounted displays using video passthrough remains elusive despite significant market investment. A precise understanding of why users experience persistent discomfort even as hardware factors such as resolution and latency have dramatically improved remains an open issue. This paper investigates the impact of viewing the world through video passthrough systems on human behavioral and physiological patterns through a large-scale multimodal study. We developed a novel protocol to capture synchronized oculomotor, kinematic, and physiological data during a block assembly task requiring complex hand-eye coordination. Using a within-subject design (N=110), we evaluated both natural and passthrough viewing conditions. Our results reveal a four-fold suppression of rotational head velocity and a pronounced decoupling of head-gaze coordination. This suggests motor caution being employed as an adaptive strategy - which we term "Passthrough Rigidity". This phenomenon appears to shift the information-gathering burden to the oculomotor system, resulting in significantly longer fixation durations and restricted visual search patterns. These kinematic shifts directly correlate with poorer task performance and measurable physiological cost, evidenced by a significant reduction in blink duration and increased reports of ocular strain and cognitive load. We conclude that current passthrough implementations induce a measurable shift from flexible exploration to motor caution, where task performance is preserved at the cost of user comfort and biomechanical efficiency. These findings provide a novel quantitative framework for evaluating and improving future XR devices, establishing that resolving "comfort" for passthrough requires addressing the deep-seated biomechanical compensations caused by mediated perception. Data available at https://data.nvision.eecs.yorku.ca/Passthrough

cs.HC↗

arXiv2026

PoseCraft: Tokenized 3D Body Landmark and Camera Conditioning for Photorealistic Human Image Synthesis

Digitizing humans and synthesizing photorealistic avatars with explicit 3D pose and camera controls are central to VR, telepresence, and entertainment. Existing skinning-based workflows require laborious manual rigging or template-based fittings, while neural volumetric methods rely on canonical templates and re-optimization for each unseen pose. We present PoseCraft, a diffusion framework built around tokenized 3D interface: instead of relying only on rasterized geometry as 2D control images, we encode sparse 3D landmarks and camera extrinsics as discrete conditioning tokens and inject them into diffusion via cross-attention. Our approach preserves 3D semantics by avoiding 2D re-projection ambiguity under large pose and viewpoint changes, and produces photorealistic imagery that faithfully captures identity and appearance. To train and evaluate at scale, we also implement GenHumanRF, a data generation workflow that renders diverse supervision from volumetric reconstructions. Our experiments show that PoseCraft achieves significant perceptual quality improvement over diffusion-centric methods, and attains better or comparable metrics to latest volumetric rendering SOTA while better preserving fabric and hair details.

cs.CV↗

arXiv2025

Restereo: Diffusion stereo video generation and restoration

Stereo video generation has been gaining increasing attention with recent advancements in video diffusion models. However, most existing methods focus on generating 3D stereoscopic videos from monocular 2D videos. These approaches typically assume that the input monocular video is of high quality, making the task primarily about inpainting occluded regions in the warped video while preserving disoccluded areas. In this paper, we introduce a new pipeline that not only generates stereo videos but also enhances both left-view and right-view videos consistently with a single model. Our approach achieves this by fine-tuning the model on degraded data for restoration, as well as conditioning the model on warped masks for consistent stereo generation. As a result, our method can be fine-tuned on a relatively small synthetic stereo video datasets and applied to low-quality real-world videos, performing both stereo video generation and restoration. Experiments demonstrate that our method outperforms existing approaches both qualitatively and quantitatively in stereo video generation from low-resolution inputs.

cs.CV↗

arXiv2025

Geometry Aware Passthrough Mitigates Cybersickness

Virtual Reality headsets isolate users from the real-world by restricting their perception to the virtual-world. Video See-Through (VST) headsets address this by utilizing world-facing cameras to create Augmented Reality experiences. However, directly displaying camera feeds causes visual discomfort and cybersickness due to the inaccurate perception of scale and exaggerated motion parallax. This paper demonstrates the potential of geometry aware passthrough systems in mitigating cybersickness through accurate depth perception. We first present a methodology to benchmark and compare passthrough algorithms. Furthermore, we design a protocol to quantitatively measure cybersickness experienced by users in VST headsets. Using this protocol, we conduct a user study to compare direct passthrough and geometry aware passthrough systems. To the best of our knowledge, our study is the first one to reveal significantly reduced nausea, disorientation, and total scores of cybersickness with geometry aware passthrough. It also uncovers several potential avenues to further mitigate visually-induced discomfort.

cs.HC↗