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Lior Shapira

dblp:06/3284 · DBLP profile ↗
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17ranked-venue papers
7as first author
3since 2021 · last 2024
—ORCID · unresolved

Domains — the database's venue-derived domains; a paper can count in several

Graphics, computer vision, multimedia, augmented reality and games · 13 · 6 first-author · 2 since 2021Artificial intelligence and machine learning · 7 · 2 first-author · 3 since 2021Human-computer interaction and ubiquitous computing · 4 · 2 first-author

Expertise — from the expertise taxonomy: the topics of the expert's papers under the CCF categories. A weight counts papers with recency: 1 for a paper about the topic, 0.3 when the topic is its context, halved every five years.

Artificial intelligence
4 papers
Segmentation and scene understanding · 37% Representation and self-supervised learning · 31% Generative modeling · 24%
Computer graphics and multimedia
5 papers
Visual content generation and editing · 51% Computer animation and physical simulation · 26% Virtual and augmented reality · 15%
Human-computer interaction and pervasive computing
3 papers
Immersive interaction · 60% Interaction techniques and input · 22% Learning and educational technologies · 6%

Topics — the 23 heaviest of 26, each with the papers that count most for it

TopicWeightPapersLastEvidence papers
Machine learning › Generative modeling › masked generative modeling
masked generative transformer
0.812024
MaskINT: Video Editing via Interpolative Non-autoregressive Masked Transformers · CVPR 2024
Computer animation and physical simulation › keyframe animation
keyframe interpolation
0.812024
MaskINT: Video Editing via Interpolative Non-autoregressive Masked Transformers · CVPR 2024
Visual content generation and editing › video editing
text-driven video editing
0.812024
MaskINT: Video Editing via Interpolative Non-autoregressive Masked Transformers · CVPR 2024
Visual content generation and editing
video editing
0.812024
MaskINT: Video Editing via Interpolative Non-autoregressive Masked Transformers · CVPR 2024
Computer vision › Segmentation and scene understanding
annotation-efficient segmentation
0.512021
Contrastive Learning for Label Efficient Semantic Segmentation · ICCV 2021
Machine learning › Representation and self-supervised learning
contrastive learning
0.512021
Contrastive Learning for Label Efficient Semantic Segmentation · ICCV 2021
Machine learning › Representation and self-supervised learning › contrastive learning › dense contrastive learning
pixel-level contrastive learning
0.512021
Contrastive Learning for Label Efficient Semantic Segmentation · ICCV 2021
Computer vision › Segmentation and scene understanding
semantic segmentation
0.512021
Contrastive Learning for Label Efficient Semantic Segmentation · ICCV 2021
Immersive interaction
virtual reality interaction
0.522016
Reality Skins: Creating Immersive and Tactile Virtual Environments · ISMAR 2016
TactileVR: Integrating Physical Toys into Learn and Play Virtual Reality Experiences · ISMAR 2016
Interaction techniques and input › post-WIMP interaction › embodied interaction
physical object interaction
0.212016
TactileVR: Integrating Physical Toys into Learn and Play Virtual Reality Experiences · ISMAR 2016
Computer vision › Segmentation and scene understanding › perceptual grouping
contour completion
0.212014
A Contour Completion Model for Augmenting Surface Reconstructions · ECCV (3) 2014
Computer vision › 3D vision › 3d reconstruction
surface reconstruction
0.212014
A Contour Completion Model for Augmenting Surface Reconstructions · ECCV (3) 2014
Geometric modeling and processing
shape analysis
0.112010
Contextual Part Analogies in 3D Objects · Int. J. Comput. Vis. 2010
Data mining
clustering
0.112009
Mode-detection via median-shift · ICCV 2009
Data mining › clustering › density-based clustering
mode seeking
0.112009
Mode-detection via median-shift · ICCV 2009
Algorithms and data structures › data structure design › search structures › hashing
locality-sensitive hashing
0.112009
Mode-detection via median-shift · ICCV 2009
Algorithms and data structures › similarity search
nearest neighbor search
0.112009
Mode-detection via median-shift · ICCV 2009
Geometric modeling and processing › 3d reconstruction
3d scene reconstruction
0.112016
Reality Skins: Creating Immersive and Tactile Virtual Environments · ISMAR 2016
Collaborative and social computing › collaborative virtual environments
collaborative virtual reality
0.112016
TactileVR: Integrating Physical Toys into Learn and Play Virtual Reality Experiences · ISMAR 2016
Learning and educational technologies › immersive learning
virtual reality learning
0.112016
TactileVR: Integrating Physical Toys into Learn and Play Virtual Reality Experiences · ISMAR 2016
Geometric modeling and processing
surface reconstruction
0.112014
A Contour Completion Model for Augmenting Surface Reconstructions · ECCV (3) 2014
Computer vision › 3D vision › 3d shape analysis
3d shape understanding
0.012010
Contextual Part Analogies in 3D Objects · Int. J. Comput. Vis. 2010
Computer vision › 3D vision
shape matching
0.012010
Contextual Part Analogies in 3D Objects · Int. J. Comput. Vis. 2010

Methods — techniques the papers use, named apart from their topics

masked generative transformer · 1.5diffusion model · 1.5constraint satisfaction · 0.7semidefinite relaxation · 0.5markov chain monte-carlo optimization · 0.5cross-entropy fine-tuning · 0.5contrastive pre-training · 0.5motion tracking · 0.2gesture inference · 0.2tukey median · 0.2random projection · 0.2median-shift · 0.2stochastic move making · 0.2self-localization · 0.2projector-depth camera units · 0.2auto-calibration · 0.2
YearPublicationVenuePosition
2024 MaskINT: Video Editing via Interpolative Non-autoregressive Masked Transformers
abstract
Recent advances in generative AI have significantly enhanced image and video editing, particularly in the context of text prompt control. State-of-the-art approaches predominantly rely on diffusion models to accomplish these tasks. However, the computational demands of diffusion-based methods are substantial, often necessitating large-scale paired datasets for training, and therefore challenging the deployment in real applications. To address these issues, this paper breaks down the text-based video editing task into two stages. First, we leverage an pre-trained text-to-image diffusion model to simultaneously edit few keyframes in an zero-shot way. Second, we introduce an efficient model called MaskINT, which is built on non-autoregressive masked generative transformers and specializes in frame interpolation between the edited keyframes, using the structural guidance from intermediate frames. Experimental results suggest that our MaskINT achieves comparable performance with diffusion-based methodologies, while significantly improve the inference time. This research offers a practical solution for text-based video editing and showcases the potential of non-autoregressive masked generative transformers in this domain.
Shahin Mahdizadehaghdam, Bichen Wu, Yuchao Gu, Wenliang Zhao, Lior Shapira, Xiaohui Xie
CVPR7
2022 2.5D visual relationship detection
Yu-Chuan Su, Soravit Changpinyo, Xiangning Chen, Sathish Thoppay, Cho-Jui Hsieh, Lior Shapira, Radu Soricut, Hartwig Adam, Matthew Brown 0001, Ming-Hsuan Yang 0001, Boqing Gong
Comput. Vis. Image Underst.6
2021 Contrastive Learning for Label Efficient Semantic Segmentation
abstract
Collecting labeled data for the task of semantic segmentation is expensive and time-consuming, as it requires dense pixel-level annotations. While recent Convolutional Neural Network (CNN) based semantic segmentation approaches have achieved impressive results by using large amounts of labeled training data, their performance drops significantly as the amount of labeled data decreases. This happens because deep CNNs trained with the de facto cross-entropy loss can easily overfit to small amounts of labeled data. To address this issue, we propose a simple and effective contrastive learning-based training strategy in which we first pretrain the network using a pixel-wise, label-based contrastive loss, and then fine-tune it using the cross-entropy loss. This approach increases intra-class compactness and inter-class separability, thereby resulting in a better pixel classifier. We demonstrate the effectiveness of the proposed training strategy using the Cityscapes and PASCAL VOC 2012 segmentation datasets. Our results show that pretraining with the proposed contrastive loss results in large performance gains (more than 20% absolute improvement in some settings) when the amount of labeled data is limited. In many settings, the proposed contrastive pretraining strategy, which does not use any additional data, is able to match or outperform the widely-used ImageNet pretraining strategy that uses more than a million additional labeled images.
Xiangyun Zhao, Raviteja Vemulapalli, Philip Andrew Mansfield, Boqing Gong, Bradley Green, Lior Shapira, Ying Wu 0001
ICCV6
2017 ASIST: Automatic semantically invariant scene transformation
Or Litany, Tal Remez, Daniel Freedman, Lior Shapira, Alexander M. Bronstein, Ran Gal
Comput. Vis. Image Underst.4
2016 TactileVR: Integrating Physical Toys into Learn and Play Virtual Reality Experiences
abstract
We present TactileVR, a proof-of-concept virtual reality system in which a user is free to move around and interact with physical objects and toys, which are represented in the virtual world. By integrating tracking information from the head, hands and feet of the user, as well as the objects, we infer complex gestures and interactions such as shaking a toy, rotating a steering wheel, or clapping your hands. We create educational and recreational experiences for kids, which promote exploration and discovery, while feeling intuitive and safe. In each experience objects have a unique appearance and behavior e.g. in an electric circuits lab toy blocks serve as switches, batteries and light bulbs.We conducted a user study with children ages 5–11, who experienced TactileVR and interacted with virtual proxies of physical objects. Children took instantly to the TactileVR environment, intuitively discovered a variety of interactions, and completed tasks faster than with non-tactile virtual objects. Moreover, the presence of physical toys created the opportunity for collaborative play, even when only some of the kids were using a VR headset.
Lior Shapira, Judith Amores, Xavier Benavides
ISMAR1
2016 Reality Skins: Creating Immersive and Tactile Virtual Environments
abstract
Reality Skins enables mobile and large-scale virtual reality experiences, dynamically generated based on the user's environment. A head-mounted display (HMD) coupled with a depth camera is used to scan the user's surroundings: reconstruct geometry, infer floor plans, and detect objects and obstacles. From these elements we generate a Reality Skin, a 3D environment which replaces office or apartment walls with the corridors of a spaceship or underground tunnels, replacing chairs and desks, sofas and beds with crates and computer consoles, fungi and crumbling ancient statues. The placement of walls, furniture and objects in the Reality Skin attempts to approximate reality, such that the user can move around, and touch virtual objects with tactile feedback from real objects. Each possible reality skins world consists of objects, materials and custom scripts. Taking cues from the user's surroundings, we create a unique environment combining these building blocks, attempting to preserve the geometry and semantics of the real world.We tackle 3D environment generation as a constraint satisfaction problem, and break it into two parts: First, we use a Markov Chain Monte-Carlo optimization, over a simple 2D polygonal model, to infer the layout of the environment (the structure of the virtual world). Then, we populate the world with various objects and characters, attempting to satisfy geometric (virtual objects should align with objects in the environment), semantic (a virtual chair aligns with a real one), physical (avoid collisions, maintain stability) and other constraints. We find a discrete set of transformations for each object satisfying unary constraints, incorporate pairwise and higher-order constraints, and optimize globally using a very recent technique based on semidefinite relaxation.
Lior Shapira, Daniel Freedman
ISMAR1
2014 A Contour Completion Model for Augmenting Surface Reconstructions
Nathan Silberman, Lior Shapira, Ran Gal, Pushmeet Kohli
ECCV (3)2
2014 FLARE: Fast layout for augmented reality applications
abstract
Creating a layout for an augmented reality (AR) application which embeds virtual objects in a physical environment is difficult as it must adapt to any physical space. We propose a rule-based framework for generating object layouts for AR applications. Under our framework, the developer of an AR application specifies a set of rules (constraints) which enforce self-consistency (rules regarding the inter-relationships of application components) and scene-consistency (application components are consistent with the physical environment they are placed in). When a user enters a new environment, we create, in real-time, a layout for the application, which is consistent with the defined constraints (as much as possible). We find the optimal configurations for each object by solving a constraint-satisfaction problem. Our stochastic move making algorithm is domain-aware, and allows us to efficiently converge to a solution for most rule-sets. In the paper we demonstrate several augmented reality applications that automatically adapt to different rooms and changing circumstances in each room.
Ran Gal, Lior Shapira, Eyal Ofek, Pushmeet Kohli
ISMAR2
2014 RoomAlive: magical experiences enabled by scalable, adaptive projector-camera units
abstract
RoomAlive is a proof-of-concept prototype that transforms any room into an immersive, augmented entertainment experience. Our system enables new interactive projection mapping experiences that dynamically adapts content to any room. Users can touch, shoot, stomp, dodge and steer projected content that seamlessly co-exists with their existing physical environment. The basic building blocks of RoomAlive are projector-depth camera units, which can be combined through a scalable, distributed framework. The projector-depth camera units are individually auto-calibrating, self-localizing, and create a unified model of the room with no user intervention. We investigate the design space of gaming experiences that are possible with RoomAlive and explore methods for dynamically mapping content based on room layout and user position. Finally we showcase four experience prototypes that demonstrate the novel interactive experiences that are possible with RoomAlive and discuss the design challenges of adapting any game to any room.
Brett R. Jones, Rajinder Sodhi, Michael Murdock, Ravish Mehra, Hrvoje Benko, Andrew D. Wilson, Eyal Ofek, Blair MacIntyre, Nikunj Raghuvanshi, Lior Shapira
UIST10
2013 Image deblurring using maps of highlights
abstract
In deblurring an image, we seek to recover the original sharp image. However, without knowledge of the blurring process, we cannot expect to recover the image perfectly. We propose a deblurring method of a single-image where the blur kernel is directly estimated from highlight spots or streaks with high intensity value. These highlighted points can be represented by specular reflection of light that may appear in the eye, on a shiny surface, or in small light sources present in the image. In this work, we detect automatically these high-lighted points in a blurred image. Therefore, creating a map of highlight, which is used as a guide to extract automatically a single highlight from the blurred image. Due to its unique nature, it is demosntrated that the highlighted points are a good estimation of the blur kernel and a sharp image is restored using these kernel. The experimental results show the performance of this method in comparison to several other deblurring methods.
Fabiane Queiroz, Ing Ren Tsang, Lior Shapira, Ron Banner
ICASSP3
2012 Black is Green: Adaptive Color Transformation For Reduced Ink Usage
abstract
Abstract A vast majority of color transformations applied to an image in the digital press industry are static and pre‐calculated. In order to achieve the best quality on a wide variety of different images, these transformations tend to be highly conservative with respect to the use of black ink. This results in excessive use of inks, which has a negative economic and environmental impact. We present a method for dynamic computation of color transformation based on image content, with the aim to reduce ink usage. We analyze the image, and predict areas in which quality artifacts that may result from such a reduction will be masked by the image content. These areas include detailed textures, noisy areas and structure. We then replace the image CMYK values by a new combination with increased black. Our algorithm ensures negligible color shifts in the resulting image, and no visible reduction in quality. We achieve an average of over 10% ink savings.
Lior Shapira, Boris Oicherman
Comput. Graph. Forum1
2010 Contextual Part Analogies in 3D Objects
Lior Shapira, Shy Shalom, Ariel Shamir, Daniel Cohen-Or, Hao (Richard) Zhang
Int. J. Comput. Vis.1
2009 One-sided object cutout using principal-channels
abstract
We introduce principal-channels for cutting out objects from an image by one-sided scribbles. We demonstrate that few scribbles, all from within the object of interest, are sufficient to mark it out. One-sided scribbles provide significantly less information than two-sided ones. Thus, it is required to maximize the use of image-information. Our approach is to first analyze the image with a large filter bank and generate a high-dimensional feature space. We then extract a set of principal-channels that discern one object from another. We show that by applying an iterative graph-cut optimization over the principal-channels, we can cut out the object of interest.
Lior Gavish, Lior Shapira, Lior Wolf, Daniel Cohen-Or
CAD/Graphics2
2009 Mode-detection via median-shift
abstract
Median-shift is a mode seeking algorithm that relies on computing the median of local neighborhoods, instead of the mean. We further combine median-shift with Locality Sensitive Hashing (LSH) and show that the combined algorithm is suitable for clustering large scale, high dimensional data sets. In particular, we propose a new mode detection step that greatly accelerates performance. In the past, LSH was used in conjunction with mean shift only to accelerate nearest neighbor queries. Here we show that we can analyze the density of the LSH bins to quickly detect potential mode candidates and use only them to initialize the median-shift procedure. We use the median, instead of the mean (or its discrete counterpart - the medoid) because the median is more robust and because the median of a set is a point in the set. A median is well defined for scalars but there is no single agreed upon extension of the median to high dimensional data. We adopt a particular extension, known as the Tukey median, and show that it can be computed efficiently using random projections of the high dimensional data onto 1D lines, just like LSH, leading to a tightly integrated and efficient algorithm.
Lior Shapira, Shai Avidan, Ariel Shamir
ICCV1
2009 Image Appearance Exploration by Model-Based Navigation
abstract
Abstract Changing the appearance of an image can be a complex and non‐intuitive task. Many times the target image colors and look are only known vaguely and many trials are needed to reach the desired results. Moreover, the effect of a specific change on an image is difficult to envision, since one must take into account spatial image considerations along with the color constraints. Tools provided today by image processing applications can become highly technical and non‐intuitive including various gauges and knobs. In this paper we introduce a method for changing image appearance by navigation, focusing on recoloring images. The user visually navigates a high dimensional space of possible color manipulations of an image. He can either explore in it for inspiration or refine his choices by navigating into sub regions of this space to a specific goal. This navigation is enabled by modeling the chroma channels of an image's colors using a Gaussian Mixture Model (GMM). The Gaussians model both color and spatial image coordinates, and provide a high dimensional parameterization space of a rich variety of color manipulations. The user's actions are translated into transformations of the parameters of the model, which recolor the image. This approach provides both inspiration and intuitive navigation in the complex space of image color manipulations.
Lior Shapira, Ariel Shamir, Daniel Cohen-Or
Comput. Graph. Forum1
2008 Consistent mesh partitioning and skeletonisation using the shape diameter function
Lior Shapira, Ariel Shamir, Daniel Cohen-Or
Vis. Comput.1
2006 Mesh analysis using geodesic mean-shift
Ariel Shamir, Lior Shapira, Daniel Cohen-Or
Vis. Comput.2