EDBT 2026 Demo / reviewers in the wild / expert
Praneeth Chakravarthula
dblp:224/0700
· DBLP profile ↗
31ranked-venue papers
9as first author
23since 2021 · last 2026
0000-0002-3092-7435ORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Graphics, computer vision, multimedia, augmented reality and games · 30 · 9 first-author · 22 since 2021Human-computer interaction and ubiquitous computing · 8 · 1 first-author · 5 since 2021Artificial intelligence and machine learning · 3 · 1 first-author · 3 since 2021Databases, data management, data science and information retrieval · 1 · 1 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | UniCoRN: Latent Diffusion-based Unified Controllable Image Restoration Network across Multiple DegradationsabstractImage restoration is essential for enhancing degraded images across computer vision tasks. However, most existing methods address only a single type of degradation (e.g., blur, noise, or haze) at a time, limiting their real-world applicability where multiple degradations often occur simultaneously. In this paper, we propose UniCoRN, a unified image restoration approach capable of handling multiple degradation types simultaneously using a multi-head diffusion model. Specifically, we uncover the potential of low-level visual cues extracted from images in guiding a controllable diffusion model for real-world image restoration, and design a multi-head control network adaptable via a mixture-of-experts strategy. We train our model without any prior assumption of specific degradations, through a smartly designed curriculum learning recipe. Additionally, we also introduce METARESTORE, a metalens imaging benchmark containing images with multiple degradations and artifacts. Extensive evaluations on several challenging datasets, including our benchmark, demonstrate that our method achieves significant performance gains and can robustly restore images with severe degradations. Code and dataset is available in our project page. Debabrata Mandal, Soumitri Chattopadhyay, Guansen Tong, Praneeth Chakravarthula |
WACV | 4 |
| 2026 | Enabling High-Quality In-the-Wild Imaging from Severely Aberrated Metalens Bursts
Debabrata Mandal, Zhihan Peng, Praneeth Chakravarthula |
WACV | 4 |
| 2026 | Overdriving Visual Depth Perception via Sound Modulation in VRabstractOur ability to perceive and navigate the spatial world is a cornerstone of human experience, relying on the integration of visual and auditory cues to form a coherent sense of depth and distance. In stereoscopic 3D vision, depth perception requires fixation of both eyes on a target object, which is achieved through vergence movements, with convergence for near objects and divergence for distant ones. In contrast, auditory cues provide complementary depth information through variations in loudness, interaural differences (IAD), and the frequency spectrum. We investigate the interaction between visual and auditory cues and examine how contradictory auditory information can overdrive visual depth perception in virtual reality (VR). When a new visual target appears, we introduce a spatial discrepancy between the visual and auditory cues: the visual target is shifted closer to the previously fixated object, while the corresponding sound localization is displaced in the opposite direction. By integrating these conflicting cues through multimodal processing, the resulting percept is biased toward the intended depth location. This audiovisual fusion counteracts depth compression, thus reducing the required vergence magnitude and enabling faster gaze retargeting. Such audio-driven depth enhancement may further help mitigate the vergence-accommodation conflict (VAC) in scenarios where physical depth must be compressed. In a series of psychophysical studies, we first assess the efficiency of depth overdriving for various VR-relevant combinations of initial fixations and shifted target locations, considering different scenarios of audio displacements and their loudness and frequency parameters. Next, we quantify the resulting speedup in gaze retargeting for target shifts that can be successfully overdriven by sound manipulations. Finally, we apply our method in a naturalistic VR scenario where user interface interactions with the scene show an extended perceptual depth. Daniel Jiménez Navarro, Colin Groth, Jorge Pina, Qi Sun 0003, Praneeth Chakravarthula, Karol Myszkowski, Hans-Peter Seidel, Ana Serrano |
IEEE Trans. Vis. Comput. Graph. | 6 |
| 2025 | Event Fields: Capturing Light Fields at High Speed, Resolution, and Dynamic RangeabstractEvent cameras, which feature pixels that independently respond to changes in brightness, are becoming increasingly popular in high- speed applications due to their lower latency, reduced bandwidth requirements, and enhanced dynamic range compared to traditional frame- based cameras. Numerous imaging and vision techniques have leveraged event cameras for high- speed scene understanding by capturing high- framerate, high- dynamic range videos, primarily utilizing the temporal advantages inherent to event cameras. Additionally, imaging and vision techniques have utilized the light field—a complementary dimension to temporal information—for enhanced scene understanding.In this work, we propose "Event Fields", a new approach that utilizes innovative optical designs for event cameras to capture light fields at high speed. We develop the underlying mathematical framework for Event Fields and introduce two foundational frameworks to capture them practically: spatial multiplexing to capture temporal derivatives and temporal multiplexing to capture angular derivatives. To realize these, we design two complementary optical setups— one using a kaleidoscope for spatial multiplexing and another using a galvanometer for temporal multiplexing. We evaluate the performance of both designs using a custom-built simulator and real hardware prototypes, showcasing their distinct benefits. Our event fields unlock the full advantages of typical light fields—like post- capture refocusing and depth estimation—now supercharged for high- speed and high- dynamic range scenes. This novel light- sensing paradigm opens doors to new applications in photography, robotics, and AR/VR, and presents fresh challenges in rendering and machine learning. Ziyuan Qu, Zihao Zou, Vivek Boominathan, Praneeth Chakravarthula, Adithya Kumar Pediredla |
CVPR | 4 |
| 2025 | DOF-GS: Adjustable Depth-of-Field 3D Gaussian Splatting for Post-Capture Refocusing, Defocus Rendering and Blur Removalabstract3D Gaussian Splatting (3DGS) techniques have recently enabled high-quality 3D scene reconstruction and real-time novel view synthesis. These approaches, however, are limited by the pinhole camera model and lack effective modeling of defocus effects. Departing from this, we introduce DOF-GS — a new 3DGS-based framework with a finite-aperture camera model and explicit, differentiable defocus rendering, enabling it to function as a post-capture control tool. By training with multi-view images with moderate defocus blur, DOF-GS learns inherent camera characteristics and reconstructs sharp details of the underlying scene, particularly, enabling rendering of varying DOF effects through on-demand aperture and focal distance control, post-capture and optimization. Additionally, our framework extracts circle-of-confusion cues during optimization to identify in-focus regions in input views, enhancing the reconstructed 3D scene details. Experimental results demonstrate that DOF-GS supports post-capture refocusing, adjustable defocus and high-quality all-in-focus rendering, from multi-view images with uncalibrated defocus blur. Praneeth Chakravarthula, Baoquan Chen |
CVPR | 2 |
| 2025 | HoloZip: High Hologram Compression via Latent-of-Latent CodingabstractHolographic displays are gaining increasing popularity, particularly as a holy grail solution to augmented and virtual reality (AR/VR) wearable displays. However, the generation of holograms is computationally intensive for AR/VR edge devices, which are expected to be compact and lightweight with low power consumption and heat dissipation to last all day. To address this, we propose a distributed hologram generation framework, dubbed HoloZip, to jointly generate, compress, transmit, and decode computer-generated holograms across the cloud-edge devices. Specifically, we perform compute intensive hologram generation via a vision transformer based backbone on the cloud, compress and transmit before decoding on a local edge device by a lightweight model. Our HoloZip framework supports both both 2D/3D holograms as well as holographic videos, achieving a reconstruction quality of over 30 dB in PSNR (lossy compression standard) with bit rates as low as 0.6 bits per pixel as validated by experiments. Huaizhi Qu, Ruichen Zhang 0004, Hengyu Lian, Mufan Qiu, Samarjit Chakraborty, Henry Fuchs, Tianlong Chen 0001, Praneeth Chakravarthula |
ICCP | 9 |
| 2025 | Why Slow Feels Fast and Fast Feels Slow: Evaluating and Predicting Speed MisperceptionabstractHuman perception of speed is largely driven by visual cues. However, our subjective estimations of speed are influenced by several factors that can lead to deceptive cues and speed misperception. While some prior studies have explored individual effects on speed perception, such as contrast, spatial frequency, and temporal frequency, their combined influence remains underexamined, particularly in immersive VR environments. In this work, we systematically investigate the influence and interplay of four visual factors—contrast, spatial frequency, temporal frequency, and eccentricity—on human perception of speed. To this end, we conduct a psychophysical study measuring subjective speed judgments across controlled stimuli and reveal significant perceptual biases induced by these factors. Based on our collected data, we learn a model to predict the underestimation or overestimation of perceived speed from visual scene properties. We apply and validate our findings in three immersive environments and demonstrate their influence on common VR scenarios. Finally, we discuss how understanding the factors that shape speed perception can drive the design of perceptually aligned virtual environments, with potential future applications such as correcting speed misperception and conceivably mitigating visual-vestibular conflicts by modulating perceived speed. Colin Groth, Daniel Jiménez Navarro, Zihao Zou, Ana Serrano, Karol Myszkowski, Qi Sun 0003, Praneeth Chakravarthula |
ISMAR | 9 |
| 2025 | Robust Single-shot Structured Light 3D Imaging via Neural Feature DecodingabstractWe consider the problem of active 3D imaging using single-shot structured light systems, which are widely employed in commercial 3D sensing devices such as Apple Face ID and Intel RealSense. Traditional structured light methods typically decode depth correspondences through pixel-domain matching algorithms, resulting in limited robustness under challenging scenarios like occlusions, fine-structured details, and non-Lambertian surfaces. Inspired by recent advances in neural feature matching, we propose a learning-based structured light decoding framework that performs robust correspondence matching within feature space rather than the fragile pixel domain. Our method extracts neural features from the projected patterns and captured infrared (IR) images, explicitly incorporating their geometric priors by building cost volumes in feature space, achieving substantial performance improvements over pixel-domain decoding approaches. To further enhance depth quality, we introduce a depth refinement module that leverages strong priors from large-scale monocular depth estimation models, improving fine detail recovery and global structural coherence. To facilitate effective learning, we develop a physically-based structured light rendering pipeline, generating nearly one million synthetic pattern-image pairs with diverse objects and materials for indoor settings. Experiments demonstrate that our method, trained exclusively on synthetic data with multiple structured light patterns, generalizes well to real-world indoor environments, effectively processes various pattern types without retraining, and consistently outperforms both commercial structured light systems and passive stereo RGB-based depth estimation methods. Code and data are available at https://github.com/Namisntimpot/NSL Qiyu Dai, Lihan Li, Praneeth Chakravarthula, He Sun 0010, Baoquan Chen, Wenzheng Chen |
SIGGRAPH Asia | 4 |
| 2025 | Perceptually-Guided Acoustic "Foveation"abstractRealistic spatial audio rendering improves immersion in virtual environments. However, the computational complexity of acoustic propagation increases linearly with the number of sources. Consequently, real-time accurate acoustic rendering becomes challenging in highly dynamic scenarios such as virtual and augmented reality (VR/AR). Exploiting the fact that human spatial sensitivity of acoustic sources is not equal at azimuth eccentricities in the horizontal plane, we introduce a perceptually-aware acoustic "foveation" guidance model to the audio rendering pipeline, which can integrate audio sources that are not spatially resolvable by human listeners. To this end, we first conduct a series of psychophysical studies to measure the minimum resolvable audible angular distance under various spatial and background conditions. We leverage this data to derive an azimuth-characterized real-time acoustic foveation algorithm. Numerical analysis and subjective user studies in VR environments demonstrate our method’s effectiveness in significantly reducing acoustic rendering workload, without compromising users’ spatial perception of audio sources. We believe that the presented research will motivate future investigation into the new frontier of modeling and leveraging human multimodal perceptual limitations — beyond the extensively studied visual acuity — for designing efficient VR/AR systems. Kenneth Chen, Irán R. Román, Juan Pablo Bello, Qi Sun 0003, Praneeth Chakravarthula |
VR | 6 |
| 2025 | Multimodal Neural Acoustic Fields for Immersive Mixed RealityabstractWe introduce multimodal neural acoustic fields for synthesizing spatial sound and enabling the creation of immersive auditory experiences from novel viewpoints and in completely unseen new environments, both virtual and real. Extending the concept of neural radiance fields to acoustics, we develop a neural network-based model that maps an environment's geometric and visual features to its audio characteristics. Specifically, we introduce a novel hybrid transformer-convolutional neural network to accomplish two core tasks: capturing the reverberation characteristics of a scene from audio-visual data, and generating spatial sound in an unseen new environment from signals recorded at sparse positions and orientations within the original scene. By learning to represent spatial acoustics in a given environment, our approach enables creation of realistic immersive auditory experiences, thereby enhancing the sense of presence in augmented and virtual reality applications. We validate the proposed approach on both synthetic and real-world visual-acoustic data and demonstrate that our method produces nonlinear acoustic effects such as reverberations, and improves spatial audio quality compared to existing methods. Furthermore, we also conduct subjective user studies and demonstrate that the proposed framework significantly improves audio perception in immersive mixed reality applications. Guaneen Tong, Johnathan Chi-Ho Leung, Haosheng Shi, Liujie Zheng, Shengze Wang 0002, Arryn Carlos O'Brien, Ashley Paula-Ann Neall, Grace Fei, Martim Gaspar, Praneeth Chakravarthula |
IEEE Trans. Vis. Comput. Graph. | 11 |
| 2024 | End-to-End Hybrid Refractive-Diffractive Lens Design with Differentiable Ray-Wave Model
Xinge Yang, Kunyi Wang, Praneeth Chakravarthula, Qiang Fu 0002, Wolfgang Heidrich |
SIGGRAPH Asia | 4 |
| 2023 | Seeing With Sound: Long-Range Acoustic Beamforming for Multimodal Scene UnderstandingabstractMobile robots, including autonomous vehicles rely heavily on sensors that use electromagnetic radiation like lidars, radars and cameras for perception. While effective in most scenarios, these sensors can be unreliable in unfavorable environmental conditions, including low-light scenarios and adverse weather, and they can only detect obstacles within their direct line-of-sight. Audible sound from other road users propagates as acoustic waves that carry information even in challenging scenarios. However, their low spatial resolution and lack of directional information have made them an overlooked sensing modality. In this work, we introduce long-range acoustic beamforming of sound produced by road users in-the-wild as a complementary sensing modality to traditional electromagnetic radiation-based sensors. To validate our approach and encourage further work in the field, we also introduce the first-ever multimodallong-range acoustic beamforming dataset. We propose a neural aperture expansion method for beamforming and demonstrate its effectiveness for multimodal automotive object detection when coupled with RGB images in challenging automotive scenarios, where camera-only approaches fail or are unable to provide ultra-fast acoustic sensing sampling rates. Data and code can be found here11light.princeton.edu/seeingwithsound. Praneeth Chakravarthula, Jim Aldon D'Souza, Ethan Tseng, Joe Bartusek, Felix Heide |
CVPR | 1 |
| 2023 | Stochastic Light Field HolographyabstractThe Visual Turing Test is the ultimate goal to evaluate the realism of holographic displays. Previous studies have focused on addressing challenges such as limited étendue and image quality over a large focal volume, but they have not investigated the effect of pupil sampling on the viewing experience in full 3D holograms. In this work, we tackle this problem with a novel hologram generation algorithm motivated by matching the projection operators of incoherent (Light Field) and coherent (Wigner Function) light transport. To this end, we supervise hologram computation using synthesized photographs, which are rendered on-the-fly using Light Field refocusing from stochastically sampled pupil states during optimization. The proposed method produces holograms with correct parallax and focus cues, which are important for passing the Visual Turing Test. We validate that our approach compares favorably to state-of-the-art CGH algorithms that use Light Field and Focal Stack supervision. Our experiments demonstrate that our algorithm improves the viewing experience when evaluated under a large variety of different pupil states. Florian Schiffers, Praneeth Chakravarthula, Nathan Matsuda, Grace Kuo, Ethan Tseng, Douglas Lanman, Felix Heide, Oliver Cossairt |
ICCP | 2 |
| 2023 | Thin On-Sensor Nanophotonic Array CamerasabstractToday's commodity camera systems rely on compound optics to map light originating from the scene to positions on the sensor where it gets recorded as an image. To record images without optical aberrations, i.e., deviations from Gauss' linear model of optics, typical lens systems introduce increasingly complex stacks of optical elements which are responsible for the height of existing commodity cameras. In this work, we investigate flat nanophotonic computational cameras as an alternative that employs an array of skewed lenslets and a learned reconstruction approach. The optical array is embedded on a metasurface that, at 700 nm height, is flat and sits on the sensor cover glass at 2.5 mm focal distance from the sensor. To tackle the highly chromatic response of a metasurface and design the array over the entire sensor, we propose a differentiable optimization method that continuously samples over the visible spectrum and factorizes the optical modulation for different incident fields into individual lenses. We reconstruct a megapixel image from our flat imager with a learned probabilistic reconstruction method that employs a generative diffusion model to sample an implicit prior. To tackle scene-dependent aberrations in broadband , we propose a method for acquiring paired captured training data in varying illumination conditions. We assess the proposed flat camera design in simulation and with an experimental prototype, validating that the method is capable of recovering images from diverse scenes in broadband with a single nanophotonic layer. Praneeth Chakravarthula, Jipeng Sun, Chenyang Lei, Gene Chou, Mario Bijelic, Johannes Froesch, Arka Majumdar, Felix Heide |
ACM Trans. Graph. | 1 |
| 2022 | Neural 3D Gaze: 3D Pupil Localization and Gaze Tracking based on Anatomical Eye Model and Neural Refraction CorrectionabstractEye tracking has already made its way to current commercial wearable display devices, and is becoming increasingly important for virtual and augmented reality applications. However, the existing model-based eye tracking solutions are not capable of conducting very accurate gaze angle measurements, and may not be sufficient to solve challenging display problems such as pupil steering or eyebox expansion. In this paper, we argue that accurate detection and localization of pupil in 3D space is a necessary intermediate step in model-based eye tracking. Existing methods and datasets either ignore evaluating the accuracy of 3D pupil localization or evaluate it only on synthetic data. To this end, we capture the first 3D pupilgaze-measurement dataset using a high precision setup with head stabilization and release it as the first benchmark dataset to evaluate both 3D pupil localization and gaze tracking methods. Furthermore, we utilize an advanced eye model to replace the commonly used oversimplified eye model. Leveraging the eye model, we propose a novel 3D pupil localization method with a deep learning-based corneal refraction correction. We demonstrate that our method outperforms the state-of-the-art works by reducing the 3D pupil localization error by 47.5% and the gaze estimation error by 18.7%. Our dataset and codes can be found here: link. Conny Lu, Praneeth Chakravarthula, Kaihao Liu, Xixiang Liu, Henry Fuchs |
ISMAR | 2 |
| 2022 | Pupil-Aware HolographyabstractHolographic displays promise to deliver unprecedented display capabilities in augmented reality applications, featuring a wide field of view, wide color gamut, spatial resolution, and depth cues all in a compact form factor. While emerging holographic display approaches have been successful in achieving large étendue and high image quality as seen by a camera, the large étendue also reveals a problem that makes existing displays impractical: the sampling of the holographic field by the eye pupil. Existing methods have not investigated this issue due to the lack of displays with large enough étendue, and, as such, they suffer from severe artifacts with varying eye pupil size and location. We show that the holographic field as sampled by the eye pupil is highly varying for existing display setups, and we propose pupil-aware holography that maximizes the perceptual image quality irrespective of the size, location, and orientation of the eye pupil in a near-eye holographic display. We validate the proposed approach both in simulations and on a prototype holographic display and show that our method eliminates severe artifacts and significantly outperforms existing approaches. Praneeth Chakravarthula, Seung-Hwan Baek, Florian Schiffers, Ethan Tseng, Grace Kuo, Andrew Maimone, Nathan Matsuda, Oliver Cossairt, Douglas Lanman, Felix Heide |
ACM Trans. Graph. | 1 |
| 2022 | Hogel-Free HolographyabstractHolography is a promising avenue for high-quality displays without requiring bulky, complex optical systems. While recent work has demonstrated accurate hologram generation of 2D scenes, high-quality holographic projections of 3D scenes has been out of reach until now. Existing multiplane 3D holography approaches fail to model wavefronts in the presence of partial occlusion while holographic stereogram methods have to make a fundamental tradeoff between spatial and angular resolution. In addition, existing 3D holographic display methods rely on heuristic encoding of complex amplitude into phase-only pixels which results in holograms with severe artifacts. Fundamental limitations of the input representation, wavefront modeling, and optimization methods prohibit artifact-free 3D holographic projections in today’s displays. To lift these limitations, we introduce hogel-free holography which optimizes for true 3D holograms, supporting both depth- and view-dependent effects for the first time. Our approach overcomes the fundamental spatio-angular resolution tradeoff typical to stereogram approaches. Moreover, it avoids heuristic encoding schemes to achieve high image fidelity over a 3D volume. We validate that the proposed method achieves 10 dB PSNR improvement on simulated holographic reconstructions. We also validate our approach on an experimental prototype with accurate parallax and depth focus effects. Praneeth Chakravarthula, Ethan Tseng, Henry Fuchs, Felix Heide |
ACM Trans. Graph. | 1 |
| 2022 | Image features influence reaction time: a learned probabilistic perceptual model for saccade latencyabstractWe aim to ask and answer an essential question " how quickly do we react after observing a displayed visual target?" To this end, we present psychophysical studies that characterize the remarkable disconnect between human saccadic behaviors and spatial visual acuity. Building on the results of our studies, we develop a perceptual model to predict temporal gaze behavior, particularly saccadic latency, as a function of the statistics of a displayed image. Specifically, we implement a neurologically-inspired probabilistic model that mimics the accumulation of confidence that leads to a perceptual decision. We validate our model with a series of objective measurements and user studies using an eye-tracked VR display. The results demonstrate that our model prediction is in statistical alignment with real-world human behavior. Further, we establish that many sub-threshold image modifications commonly introduced in graphics pipelines may significantly alter human reaction timing, even if the differences are visually undetectable. Finally, we show that our model can serve as a metric to predict and alter reaction latency of users in interactive computer graphics applications, thus may improve gaze-contingent rendering, design of virtual experiences, and player performance in e-sports. We illustrate this with two examples: estimating competition fairness in a video game with two different team colors, and tuning display viewing distance to minimize player reaction time. Budmonde Duinkharjav, Praneeth Chakravarthula, Rachel Brown, Anjul Patney, Qi Sun 0003 |
ACM Trans. Graph. | 2 |
| 2022 | Seeing through obstructions with diffractive cloakingabstractUnwanted camera obstruction can severely degrade captured images, including both scene occluders near the camera and partial occlusions of the camera cover glass. Such occlusions can cause catastrophic failures for various scene understanding tasks such as semantic segmentation, object detection, and depth estimation. Existing camera arrays capture multiple redundant views of a scene to see around thin occlusions. Such multi-camera systems effectively form a large synthetic aperture, which can suppress nearby occluders with a large defocus blur, but significantly increase the overall form factor of the imaging setup. In this work, we propose a monocular single-shot imaging approach that optically cloaks obstructions by emulating a large array. Instead of relying on different camera views, we learn a diffractive optical element (DOE) that performs depth-dependent optical encoding, scattering nearby occlusions while allowing paraxial wavefronts to be focused. We computationally reconstruct unobstructed images from these superposed measurements with a neural network that is trained jointly with the optical layer of the proposed imaging system. We assess the proposed method in simulation and with an experimental prototype, validating that the proposed computational camera is capable of recovering occluded scene information in the presence of severe camera obstruction. Zheng Shi 0003, Yuval Bahat, Seung-Hwan Baek, Qiang Fu 0002, Hadi Amata, Praneeth Chakravarthula, Wolfgang Heidrich, Felix Heide |
ACM Trans. Graph. | 7 |
| 2022 | Joint neural phase retrieval and compression for energy- and computation-efficient holography on the edgeabstractRecent deep learning approaches have shown remarkable promise to enable high fidelity holographic displays. However, lightweight wearable display devices cannot afford the computation demand and energy consumption for hologram generation due to the limited onboard compute capability and battery life. On the other hand, if the computation is conducted entirely remotely on a cloud server, transmitting lossless hologram data is not only challenging but also result in prohibitively high latency and storage. In this work, by distributing the computation and optimizing the transmission, we propose the first framework that jointly generates and compresses high-quality phase-only holograms. Specifically, our framework asymmetrically separates the hologram generation process into high-compute remote encoding (on the server), and low-compute decoding (on the edge) stages. Our encoding enables light weight latent space data, thus faster and efficient transmission to the edge device. With our framework, we observed a reduction of 76% computation and consequently 83% in energy cost on edge devices, compared to the existing hologram generation methods. Our framework is robust to transmission and decoding errors, and approach high image fidelity for as low as 2 bits-per-pixel, and further reduced average bit-rates and decoding time for holographic videos. Praneeth Chakravarthula, Qi Sun 0003, Baoquan Chen |
ACM Trans. Graph. | 2 |
| 2022 | FoV-NeRF: Foveated Neural Radiance Fields for Virtual RealityabstractVirtual Reality (VR) is becoming ubiquitous with the rise of consumer displays and commercial VR platforms. Such displays require low latency and high quality rendering of synthetic imagery with reduced compute overheads. Recent advances in neural rendering showed promise of unlocking new possibilities in 3D computer graphics via image-based representations of virtual or physical environments. Specifically, the neural radiance fields (NeRF) demonstrated that photo-realistic quality and continuous view changes of 3D scenes can be achieved without loss of view-dependent effects. While NeRF can significantly benefit rendering for VR applications, it faces unique challenges posed by high field-of-view, high resolution, and stereoscopic/egocentric viewing, typically causing low quality and high latency of the rendered images. In VR, this not only harms the interaction experience but may also cause sickness. To tackle these problems toward six-degrees-of-freedom, egocentric, and stereo NeRF in VR, we present the first gaze-contingent 3D neural representation and view synthesis method. We incorporate the human psychophysics of visual- and stereo-acuity into an egocentric neural representation of 3D scenery. We then jointly optimize the latency/performance and visual quality while mutually bridging human perception and neural scene synthesis to achieve perceptually high-quality immersive interaction. We conducted both objective analysis and subjective studies to evaluate the effectiveness of our approach. We find that our method significantly reduces latency (up to 99% time reduction compared with NeRF) without loss of high-fidelity rendering (perceptually identical to full-resolution ground truth). The presented approach may serve as the first step toward future VR/AR systems that capture, teleport, and visualize remote environments in real-time. Nianchen Deng, Zhenyi He, Jiannan Ye, Budmonde Duinkharjav, Praneeth Chakravarthula, Xubo Yang, Qi Sun 0003 |
IEEE Trans. Vis. Comput. Graph. | 5 |
| 2021 | Interacting with Information in Immersive Virtual EnvironmentsabstractIn this paper, we demonstrate the Information Interactions in Virtual Reality (IIVR) system designed and implemented to study how users interact with abstract information objects in immersive virtual environments in the context of information retrieval. Virtual reality displays are quickly growing as social and personal computing media, and understanding user interactions in these immersive environments is imperative. As a step towards effective information retrieval in such emerging platforms, our system is central to upcoming studies to observe how users engage in information triaging tasks in Virtual Reality (VR). In these studies, we will observe the effects of (1) information layouts and (2) types of interactions in VR. We believe this early system motivates researchers in understanding and designing meaningful interactions for future VR information retrieval applications. Austin R. Ward, Yiyin Gu, Sandeep Avula, Praneeth Chakravarthula |
SIGIR | 4 |
| 2021 | Gaze-Contingent Retinal Speckle Suppression for Perceptually-Matched Foveated Holographic DisplaysabstractComputer-generated holographic (CGH) displays show great potential and are emerging as the next-generation displays for augmented and virtual reality, and automotive heads-up displays. One of the critical problems harming the wide adoption of such displays is the presence of speckle noise inherent to holography, that compromises its quality by introducing perceptible artifacts. Although speckle noise suppression has been an active research area, the previous works have not considered the perceptual characteristics of the Human Visual System (HVS), which receives the final displayed imagery. However, it is well studied that the sensitivity of the HVS is not uniform across the visual field, which has led to gaze-contingent rendering schemes for maximizing the perceptual quality in various computer-generated imagery. Inspired by this, we present the first method that reduces the "perceived speckle noise" by integrating foveal and peripheral vision characteristics of the HVS, along with the retinal point spread function, into the phase hologram computation. Specifically, we introduce the anatomical and statistical retinal receptor distribution into our computational hologram optimization, which places a higher priority on reducing the perceived foveal speckle noise while being adaptable to any individual's optical aberration on the retina. Our method demonstrates superior perceptual quality on our emulated holographic display. Our evaluations with objective measurements and subjective studies demonstrate a significant reduction of the human perceived noise. Praneeth Chakravarthula, Zhan Zhang 0009, Okan Tarhan Tursun, Piotr Didyk, Qi Sun 0003, Henry Fuchs |
IEEE Trans. Vis. Comput. Graph. | 1 |
| 2020 | Improved vergence and accommodation via Purkinje Image tracking with multiple cameras for AR glassesabstractWe present a personalized, comprehensive eye-tracking solution based on tracking higher-order Purkinje images, suited explicitly for eyeglasses-style AR and VR displays. Existing eye-tracking systems for near-eye applications are typically designed to work for an on-axis configuration and rely on pupil center and corneal reflections (PCCR) to estimate gaze with an accuracy of only about 0.5°to 1°. These are often expensive, bulky in form factor, and fail to estimate monocular accommodation, which is crucial for focus adjustment within the AR glasses.Our system independently measures the binocular vergence and monocular accommodation using higher-order Purkinje reflections from the eye, extending the PCCR based methods. We demonstrate that these reflections are sensitive to both gaze rotation and lens accommodation and model the Purkinje images' behavior in simulation. We also design and fabricate a user-customized eye tracker using cheap off-the-shelf cameras and LEDs. We use an end-to-end convolutional neural network (CNN) for calibrating the eye tracker for the individual user, allowing for robust and simultaneous estimation of vergence and accommodation. Experimental results show that our solution, specifically catering to individual users, outperforms state-of-the-art methods for vergence and depth estimation, achieving an accuracy of 0.3782° and 1.108cm respectively. Conny Lu, Praneeth Chakravarthula, Yujie Tao, Steven Chen, Henry Fuchs |
ISMAR | 2 |
| 2020 | Towards Eyeglass-style Holographic Near-eye Displays with StaticallyabstractHolography is perhaps the only method demonstrated so far that can achieve a wide field of view (FOV) and a compact eyeglass-style form factor for augmented reality (AR) near-eye displays (NEDs). Unfortunately, the eyebox of such NEDs is impractically small (~ <; 1mm). In this paper, we introduce and demonstrate a design for holographic NEDs with a practical, wide eyebox of ~ 10mm and without any moving parts, based on holographic lenslets. In our design, a holographic optical element (HOE) based on a lenslet array was fabricated as the image combiner with expanded eyebox. A phase spatial light modulator (SLM) alters the phase of the incident laser light projected onto the HOE combiner such that the virtual image can be perceived at different focus distances, which can reduce the vergence-accommodation conflict (VAC). We have successfully implemented a bench-top prototype following the proposed design. The experimental results show effective eyebox expansion to a size of ~ 10mm. With further work, we hope that these design concepts can be incorporated into eyeglass-size NEDs. Xinxing Xia, Frank Guan, Andrei State, Praneeth Chakravarthula, Tat-Jen Cham, Henry Fuchs |
ISMAR | 4 |
| 2020 | Learned hardware-in-the-loop phase retrieval for holographic near-eye displaysabstractHolography is arguably the most promising technology to provide wide field-of-view compact eyeglasses-style near-eye displays for augmented and virtual reality. However, the image quality of existing holographic displays is far from that of current generation conventional displays, effectively making today's holographic display systems impractical. This gap stems predominantly from the severe deviations in the idealized approximations of the "unknown" light transport model in a real holographic display, used for computing holograms. In this work, we depart from such approximate "ideal" coherent light transport models for computing holograms. Instead, we learn the deviations of the real display from the ideal light transport from the images measured using a display-camera hardware system. After this unknown light propagation is learned, we use it to compensate for severe aberrations in real holographic imagery. The proposed hardware-in-the-loop approach is robust to spatial, temporal and hardware deviations, and improves the image quality of existing methods qualitatively and quantitatively in SNR and perceptual quality. We validate our approach on a holographic display prototype and show that the method can fully compensate unknown aberrations and erroneous and non-linear SLM phase delays, without explicitly modeling them. As a result, the proposed method significantly outperforms existing state-of-the-art methods in simulation and experimentation - just by observing captured holographic images. Praneeth Chakravarthula, Ethan Tseng, Tarun Srivastava, Henry Fuchs, Felix Heide |
ACM Trans. Graph. | 1 |
| 2019 | [DC] Auto-focus Augmented Reality Eyeglasses for both Real World and Virtual ImageryabstractNear-eye displays presenting accommodation cues, thereby mitigating the vergence-accommodation conflict, have garnered interest in the recent past. However, considering that at least 40% of US population is presbyopic and similarly a sizable world population suffering other refractive errors in eye, it requires that the users wear their prescription glasses along with the AR goggles, despite focus support for virtual imagery, making the overall experience uncomfortable. In the recent work published at ISMAR-TVCG 2018, which won a Best Paper Award, my collaborators and I presented an AR display which can automatically adjust for focus for both real and virtual imagery, avoiding an extra pair of prescription correcting glasses along with AR glasses. My recent work has been on a near-eye display design which integrates with the bifocals of a presbyopic user, thereby providing depth dependent stimuli to the user who is already well adapted to bifocal lenses. A variant of these ideas are going to be presented at IEEE VR 2018 through our accepted TVCG paper. I propose that the above mentioned works combined with my future work on integrating eye trackers and depth sensors to make the display glasses more robust and completely automatic, followed by evaluating the perceptual qualities of the display are the topics of my dissertation. Praneeth Chakravarthula |
VR | 1 |
| 2019 | Wirtinger holography for near-eye displaysabstractNear-eye displays using holographic projection are emerging as an exciting display approach for virtual and augmented reality at high-resolution without complex optical setups --- shifting optical complexity to computation. While precise phase modulation hardware is becoming available, phase retrieval algorithms are still in their infancy, and holographic display approaches resort to heuristic encoding methods or iterative methods relying on various relaxations. In this work, we depart from such existing approximations and solve the phase retrieval problem for a hologram of a scene at a single depth at a given time by revisiting complex Wirtinger derivatives, also extending our framework to render 3D volumetric scenes. Using Wirtinger derivatives allows us to pose the phase retrieval problem as a quadratic problem which can be minimized with first-order optimization methods. The proposed Wirtinger Holography is flexible and facilitates the use of different loss functions, including learned perceptual losses parametrized by deep neural networks, as well as stochastic optimization methods. We validate this framework by demonstrating holographic reconstructions with an order of magnitude lower error, both in simulation and on an experimental hardware prototype. Praneeth Chakravarthula, Yifan Peng 0001, Joel S. Kollin, Henry Fuchs, Felix Heide |
ACM Trans. Graph. | 1 |
| 2019 | Manufacturing Application-Driven Foveated Near-Eye DisplaysabstractTraditional optical manufacturing poses a great challenge to near-eye display designers due to large lead times in the order of multiple weeks, limiting the abilities of optical designers to iterate fast and explore beyond conventional designs. We present a complete near-eye display manufacturing pipeline with a day lead time using commodity hardware. Our novel manufacturing pipeline consists of several innovations including a rapid production technique to improve surface of a 3D printed component to optical quality suitable for near-eye display application, a computational design methodology using machine learning and ray tracing to create freeform static projection screen surfaces for near-eye displays that can represent arbitrary focal surfaces, and a custom projection lens design that distributes pixels non-uniformly for a foveated near-eye display hardware design candidate. We have demonstrated untethered augmented reality near-eye display prototypes to assess success of our technique, and show that a ski-goggles form factor, a large monocular field of view$(30^{o}\times 55^{o})$, and a resolution of 12 cycles per degree can be achieved. Kaan Aksit, Praneeth Chakravarthula, Kishore Rathinavel, Youngmo Jeong, Rachel A. Albert, Henry Fuchs, David P. Luebke |
IEEE Trans. Vis. Comput. Graph. | 2 |
| 2019 | Towards a Switchable AR/VR Near-eye Display with Accommodation-Vergence and Eyeglass Prescription SupportabstractIn this paper, we present our novel design for switchable AR/VR near-eye displays which can help solve the vergence-accommodation-conflict issue. The principal idea is to time-multiplex virtual imagery and real-world imagery and use a tunable lens to adjust focus for the virtual display and the see-through scene separately. With this novel design, prescription eyeglasses for near- and far-sighted users become unnecessary. This is achieved by integrating the wearer's corrective optical prescription into the tunable lens for both virtual display and see-through environment. We built a prototype based on the design, comprised of micro-display, optical systems, a tunable lens, and active shutters. The experimental results confirm that the proposed near-eye display design can switch between AR and VR and can provide correct accommodation for both. Xinxing Xia, Frank Guan, Andrei State, Praneeth Chakravarthula, Kishore Rathinavel, Tat-Jen Cham, Henry Fuchs |
IEEE Trans. Vis. Comput. Graph. | 4 |
| 2018 | FocusAR: Auto-focus Augmented Reality Eyeglasses for both Real World and Virtual ImageryabstractWe describe a system which corrects dynamically for the focus of the real world surrounding the near-eye display of the user and simultaneously the internal display for augmented synthetic imagery, with an aim of completely replacing the user prescription eyeglasses. The ability to adjust focus for both real and virtual stimuli will be useful for a wide variety of users, but especially for users over 40 years of age who have limited accommodation range. Our proposed solution employs a tunable-focus lens for dynamic prescription vision correction, and a varifocal internal display for setting the virtual imagery at appropriate spatially registered depths. We also demonstrate a proof of concept prototype to verify our design and discuss the challenges to building an auto-focus augmented reality eyeglasses for both real and virtual. Praneeth Chakravarthula, David Dunn, Kaan Aksit, Henry Fuchs |
IEEE Trans. Vis. Comput. Graph. | 1 |