Ariel Shamir

Interdisciplinary Center Herzliya | IDC · Efi Arazi School of Computer Science

We introduce an interactive technique to extract and manipulate simple 3D shapes in a single photograph. Such extraction requires an understanding of the shape's components, their projections, and their relationships. These cognitive tasks are simple for humans, but particularly difficult for automatic algorithms. Thus, our approach combines the co...

In this paper we propose failure probabilities as a semantically and mechanically meaningful measure of object fragility. We present a stochastic finite element method which exploits fast rigid body simulation and reduced-space approaches to compute spatially varying failure probabilities. We use an explicit rigid body simulation to emulate the rea...

We introduce a co-analysis method which learns a functionality model for an object category, e.g., strollers or backpacks. Like previous works on functionality, we analyze object-to-object interactions and intra-object properties and relations. Differently from previous works, our model goes beyond providing a functionality-oriented descriptor for...

We present AutoConnect, an automatic method that creates customized, 3D-printable connectors attaching two physical objects together. Users simply position and orient virtual models of the two objects that they want to connect and indicate some auxiliary information such as weight and dimensions. Then, AutoConnect creates several alternative design...

We present a method to automatically convert videos and CG animations to stylized animated line drawings. Using a data-driven approach, the animated drawings can follow the sketching style of a specific artist. Given an input video, we first extract edges from the video frames and vectorize them to curves. The curves are matched to strokes from an...

We address the problem of allowing casual users to customize parametric models while maintaining their valid state as 3D-printable functional objects. We define Fab Form as any design representation that lends itself to interactive customization by a novice user, while remaining valid and manufacturable. We propose a method to achieve these Fab For...

We address the problem of allowing casual users to customize parametric models while maintaining their valid state as 3D-printable functional objects. We define Fab Form as any design representation that lends itself to interactive customization by a novice user, while remaining valid and manufacturable. We propose a method to achieve these Fab For...

We introduce a contextual descriptor which aims to provide a geometric description of the functionality of a 3D object in the context of a given scene. Differently from previous works, we do not regard functionality as an abstract label or represent it implicitly through an agent. Our descriptor, called interaction context or ICON for short, explic...

Given the current profusion of devices for viewing media, video content created at one aspect ratio is often viewed on displays with different aspect ratios. Many previous solutions address this problem by retargeting or resizing the video, but a more general solution would re-edit the video for the new display. Our method employs the three primary...

Image completion techniques aim to complete selected regions of an image in a natural looking manner with little or no user interaction. Video Completion, the space–time equivalent of the image completion problem, inherits and extends both the difficulties and the solutions of the original 2D problem, but also imposes new ones—mainly temporal coher...

We present an approach that takes multiple videos captured by social cameras-cameras that are carried or worn by members of the group involved in an activity-and produces a coherent "cut" video of the activity. Footage from social cameras contains an intimate, personalized view that reflects the part of an event that was of importance to the camera...

We introduce focal points for characterizing, comparing, and organizing collections of complex and heterogeneous data and apply the concepts and algorithms developed to collections of 3D indoor scenes. We represent each scene by a graph of its constituent objects and define focal points as representative substructures in a scene collection. To orga...

We present a method for transforming a 3D object into a cube or a box using a continuous folding sequence. Our method produces a single, connected object that can be physically fabricated and folded from one shape to the other. We segment the object into voxels and search for a voxel-tree that can fold from the input shape to the target shape. This...

We propose a data-driven method for designing 3D models that can be fabricated. First, our approach converts a collection of expert-created designs to a dataset of parameterized design templates that includes all information necessary for fabrication. The templates are then used in an interactive design system to create new fabricable models in a d...

One embodiment of the present invention sets forth a technique for generating a three-dimensional (3D) model of an individual. The technique involves receiving pose data that includes image data associated with the individual being in a pose, selecting from a database a morphable 3D generic human model based on a gender of the individual, adjusting...

The 13 papers in this special issue can be classified into five broad thematic categories: representation, streaming, retargeting, 3-D video, and system.

We introduce an interactive technique for manipulating simple 3D shapes based on extracting them from a single photograph. Such extraction requires understanding of the components of the shape, their projections, and relations. These simple cognitive tasks for humans are particularly difficult for automatic algorithms. Thus, our approach combines t...

This paper introduces a novel content-adaptive image downscaling method. The key idea is to optimize the shape and locations of the downsampling kernels to better align with local image features. Our content-adaptive kernels are formed as a bilateral combination of two Gaussian kernels defined over space and color, respectively. This yields a conti...

Our homes and workspaces are filled with collections of dozens of artifacts laid out on surfaces such as shelves, counters, and mantles. The content and layout of these arrangements reflect both context, e.g. kitchen or living room, and style, e.g. neat or messy. Manually assembling such arrangements in virtual scenes is highly time consuming, espe...

The word ‘style’ can be interpreted in so many different ways in so many different contexts. To provide a general analysis and understanding of styles is a highly challenging problem. We pose the open question ‘how to extract styles from geometric shapes?’ and address one instance of the problem. Specifically, we present an unsupervised algorithm f...

We introduce an unsupervised co-hierarchical analysis of a set of shapes, aimed at discovering their hierarchical part structures and revealing relations between geometrically dissimilar yet functionally equivalent shape parts across the set. The core problem is that of representative co-selection. For each shape in the set, one representative hier...

A new system provides a virtual experience akin to trying on clothing. It clones the user's photographic image into a catalog of images of models wearing the desired garments. Simple offline training extracts the user's head. Segmentation accurately separates the face, hair, and background, employing both a three-kernel statistical model and graph...

We use a data-driven approach to study both style and abstraction in sketching of a human face. We gather and analyze data from a number of artists as they sketch a human face from a reference photograph. To achieve different levels of abstraction in the sketches, decreasing time limits were imposed -- from four and a half minutes to fifteen second...

We present a method for organizing a heterogeneous collection of 3D shapes for overview and exploration. Instead of relying on quantitative distances, which may become unreliable between dissimilar shapes, we introduce a qualitative analysis which utilizes multiple distance measures but only in cases where the measures can be reliably compared. Our...

Modeling 3D objects from sketches is a process that requires several challenging problems including segmentation, recognition and reconstruction. Some of these tasks are harder for humans and some are harder for the machine. At the core of the problem lies the need for semantic understanding of the shape's geometry from the sketch. In this paper we...

A method for image comparison includes reading from a memory in a computerized image processor a source image and a target image. The source and target images are segmented, using the image processor, into respective pluralities of source and target arrays, respectively including source and target array elements, each array element including a matr...

A method for image processing includes receiving in a computerized image processor a source image having a source size and a definition of a target size that is different from the source size, and defining a plurality of different sequences of two or more different image retargeting operations that when applied to the source image, generates respec...

For images, gradient domain composition methods like Poisson blending offer practical solutions for uncertain object boundaries and differences in illumination conditions. However, adapting Poisson image blending to video faces new challenges due to the added temporal dimension. In video, the human eye is sensitive to small changes in blending boun...

We present ‘Smart Scribbles’—a new scribble‐based interface for user‐guided segmentation of digital sketchy drawings. In contrast to previous approaches based on simple selection strategies, Smart Scribbles exploits richer geometric and temporal information, resulting in a more intuitive segmentation interface. We introduce a novel energy minimizat...

We introduce the geometric problem of stackabilization: how to geometrically modify a 3D object so that it is more amenable to stacking. Given a 3D object and a stacking direction, we define a measure of stackability, which is derived from the gap between the lower and upper envelopes of the object in a stacking configuration along the stacking dir...

Human Computation (HC) utilizes humans to solve problems or carry out tasks that are hard for pure computational algorithms. Many graphics and vision problems have such tasks. Previous HC approaches mainly focus on generating data in batch, to gather benchmarks, or perform surveys demanding nontrivial interactions. We advocate a tighter integration...

We present PoseShop - a pipeline to construct segmented human image database with minimal manual intervention. By downloading, analyzing, and filtering massive amounts of human images from the Internet we achieve a database which contains 400 thousands human figures that are segmented out of their background. The human figures are organized based o...

Graphic interfaces are vital when interacting with the vast amounts of information available today. A multivariate-graphs, containing typed nodes and typed links between nodes, is very often used to represent many types of data. Such graphs impose greater demands on graphical interaction techniques as they contain a great amount of information as a...

We present a framework for interactively manipulating objects in a photograph using related objects obtained from internet images. Given an image, the user selects an object to modify, and provides keywords to describe it. Objects with a similar shape are retrieved and segmented from online images matching the keywords, and deformed to correspond w...

As depth cameras become more popular, pixel depth information becomes easier to obtain. This information can clearly enhance many image processing applications. However, combining depth and color information is not straightforward as these two signals can have different noise characteristics, differences in resolution, and their boundaries do not g...

We present an algorithm for creating digital micrography images, or micrograms, a special type of calligrams created from minuscule text. These attractive text-art works successfully combine beautiful images with readable meaningful text. Traditional micrograms are created by highly skilled artists and involve a huge amount of tedious manual work....

Abstract We introduce symmetry hierarchy of man-made objects, a high-level structural representation of a 3D model providing a symmetry-induced, hierarchical organization of the model's constituent parts. Given an input mesh, we segment it into primitive parts and build an initial graph which encodes inter-part symmetries and connectivity relations...

We present cone carving, a novel space carving technique supporting topologically correct surface reconstruction from an incomplete scanned point cloud. The technique utilizes the point samples not only for local surface position estimation but also to obtain global visibility information under the assumption that each acquired point is visible fro...

The numerous works on media retargeting call for a methodological approach for evaluating retargeting results. We present the first comprehensive perceptual study and analysis of image retargeting. First, we create a benchmark of images and conduct a large scale user study to compare a representative number of state-of-the-art retargeting methods....

Abstract Many times, even if a crowd simulation looks good in general, there could be some specific individual behaviors which do not seem correct. Spotting such problems manually can become tedious, but ignoring them may harm the simulation's credibility. In this paper we present a data-driven approach for evaluating the behaviors of individuals w...

In this paper we address the problem of finding analogies between parts of 3D objects. By partitioning an object into meaningful parts and finding analogous parts in other objects, not necessarily of the same type, many analysis and modeling tasks could be enhanced. For instance, partial match queries can be formulated, annotation of parts in objec...

Videos of multi-player team sports provide a challenging domain for dynamic scene analysis. Player actions and interactions are complex as they are driven by many factors, such as the short-term goals of the individual player, the overall team strategy, the rules of the sport, and the current context of the game. We show that constrained multi-agen...

We present a system that composes a realistic picture from a simple freehand sketch annotated with text labels. The composed picture is generated by seamlessly stitching several photographs in agreement with the sketch and text labels; these are found by searching the Internet. Although online image search generates many inappropriate results, our...

We present an approach for extracting reliefs and details from relief surfaces. We consider a relief surface as a surface composed of two components: a base surface and a height function which is defined over this base. However, since the base surface is unknown, the decoupling of these components is a challenge. We show how to estimate a robust he...

We present a system that composes a realistic picture from a simple freehand sketch annotated with text labels. The composed picture is generated by seamlessly stitching several photographs in agreement with the sketch and text labels; these are found by searching the Internet. Although online image search generates many inappropriate results, our...

There are various techniques for simulating crowds, however, in most cases the quality of the simulation is measured by examining its “look-and-feel”. Even if the aggregate movement of the crowd looks natural from afar, the behaviors of individuals might look odd when examined more closely. In this paper we present a data-driven approach for evalua...

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 t...

Content aware resizing gained popularity lately and users can now choose from a battery of methods to retarget their media. However, no single retargeting operator performs well on all images and all target sizes. In a user study we conducted, we found that users prefer to combine seam carving with cropping and scaling to produce results they are s...

Two-dimensional parameterizations of meshes is a dynamic field of research. Most works focus on parameterizing complete surfaces, attempting to satisfy various con- straints on distances and angles and produce a 2D map with minimal errors. Except for devel- opable surfaces no single map can be devoid of errors, and a parametrization produced for on...

Abstract The notion of parts in a shape plays an important role in many geometry problems, including segmentation, correspondence, recognition, editing, and animation. As the fundamental geometric representation of 3D objects in computer graphics is surface-based, solutions of many such problems utilize a surface metric, a distance function defined...

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 w...

Traditional image resizing techniques are oblivious to the content of the image when changing its width or height. In contrast, media (i.e., image and video) retargeting take s content into account. For example, one would like to change the aspect ratio of a video without making human figures look too fat or too skinny, or change the size of an ima...

The increasing variety of commonly used display devices, especially mobile devices, requires adapting visual media to different resolutions and aspect ratios - a process called "retargeting." The media retargeting problem is further accentuated by the explosion of image and video content on the web. This course presents a comparative overview of th...

Resizing of 3D models can be very useful when creating new models or placing models inside different scenes. However, uniform scaling is limited in its applicability while straightforward non-uniform scaling can destroy features and lead to serious visual artifacts. Our goal is to define a method that protects model features and structures during r...

Abstract We present a review of the state of the art of segmentation and partitioning techniques of boundary meshes. Recently, these have become a part of many mesh and object manipulation algorithms in computer graphics, geometric modelling and computer aided design. We formulate the segmentation problem as an optimization problem and identify two...

Video, like images, should support content aware resizing. We present video retargeting using an improved seam carving operator. Instead of removing 1D seams from 2D images we remove 2D seam manifolds from 3D space-time volumes. To achieve this we replace the dynamic programming method of seam carving with graph cuts that are suitable for 3D volume...

Mesh partitioning and skeletonisation are fun- damental for many computer graphics and animation techniques. Because of the close link between an object's skeleton and it's boundary, these two problems are in many cases complementary. Any partitioning of the ob- ject can assist in the creation of a skeleton and any seg- mentation of the skeleton ca...

Shape retrieval can benefit from analogies among similar shapes and parts of different objects. By partitioning an object to meaningful parts and finding analogous parts in other objects, sub-parts and partial match queries can be utilized. First by searching for similar parts in the context of their shape, and second by finding similarities even a...

The curve-skeleton of a 3D object is an abstract geometrical and topological representation of its 3D shape. It maps the spatial relation of geometrically meaningful parts to a graph structure. Each arc of this graph represents a part of the object with roughly constant diameter or thickness, and approximates its centerline. This makes the curve-sk...

Effective resizing of images should not only use geometric constraints, but consider the image content as well. We present a simple image operator called seam carving that supports content-aware image resizing for both reduction and expansion. A seam is an optimal 8-connected path of pixels on a single image from top to bottom, or left to right, wh...

We present an example-based surface reconstruction method for scanned point sets. Our approach uses a database of local shape priors built from a set of given context models that are chosen specifically to match a specific scan. Local neighborhoods of the input scan are matched with enriched patches of these models at multiple scales. Hence, instea...

A 3D shape signature is a compact representation for some essence of a shape. Shape signatures are commonly utilized as a fast indexing mechanism for shape retrieval. Effective shape signatures capture some global geometric properties which are scale, translation, and rotation invariant. In this paper, we introduce an effective shape signature whic...

Surface simplification is an important application in geographic information systems. The goal is to obtain a new surface that is combinatorially as simple as possible, while maintaining a prescribed degree of similarity with the original input surface. In this paper, we propose a new terrain simplification algorithm which is based on known Digital...

Geometric manipulation of 3D objects can benefit from analogies among similar shapes and parts. However, analogies that are easily found by humans are difficult to detect and maintain in algorithms that manipulate 3D meshes. One of the reasons for this is that such analogies are perceived between 3D volumetric parts of the objects whereas models de...

The manipulation of the colors in an image and color spaces in general can be highly complex and non-intuitive. Converting the thoughts or vision of the designer to specific color modifications on an image is hard, while envisioning the effect of a specific color manipulation is difficult as well. Furthermore, recoloring must take into account spat...

Editing and manipulation of existing 3D geomet-ric objects are means to extend their repertoire and promote their availability. Traditionally, tools to compose or manipu-late objects defined by 3D meshes are in the realm of artists and experts. In this paper, we introduce a simple and effec-tive user interface for easy composition of 3D mesh-parts...

We present a deformable model to reconstruct a surface from a point cloud. The model is based on an explicit mesh representation composed of multiple competing evolving fronts. These fronts adapt to the local feature size of the target shape in a coarse–to–fine manner. Hence, they approach towards the finer (local) features of the target shape only...

The medial axis (MA) of an object is homotopy equivalent to the solid model. This makes the medial axis a natural candidate for a skeleton representation of a general solid object. In addition, the medial axis transform is useful for many applications in computer graphics and other areas. In many applications it is not only important to have a desc...

There are times when computer graphics is required to be succinct and simple. Carefully chosen simplified and static images can portray a story narration as effectively as 3D photorealistic dynamic graphics. This article presents an automatic system that transforms dynamic graphics originating from interactions in a computer game's 3D virtual world...

In this paper we introduce a versatile and robust method for analyzing the feature space associated with a given mesh surface. The method is based on the mean-shift operator which was shown to be successful in image and video processing. Its strength lays in the fact that it works in a single joint space of geometry and attributes called the featur...

Visualization of algorithms has been shown to be a useful aid for educational purposes. In this work we focus on the creation of algorithm visualizations based on viewing the visualization as a narrative. This view promotes the creator to form a central plot and define abstract participating players. Following this view, the basic elements defining...

In this report we present the state of the art on segmentation, or partitioning techniques used on boundary meshes. Recently, these have become a part of many mesh and object manipulation algorithms in computer graphics. We formulation the segmentation problem as an optimization problem and identify two primarily distinct types of mesh segmentation...

This paper presents an intelligent scissoring operator for meshes. Unlike common approaches that segment a mesh using clustering schemes, here we introduce a method that concentrates on the contours for cutting. Our approach is based on the minima rule and part salience theory from the cognitive theory. The minima rule states that human perception...

Molecular surface computations are often necessary in order to perform synthetic drug design. A critical step in this process is the computation and update of an exact boundary representation for the molecular surface (e.g. the Lee–Richards surface). In this paper we introduce efficient techniques for computing a molecular surface boundary represen...

We present a formulation of boundary mesh segmentation as an optimization problem. Previous segmentation solutions are classified according to the different segmentation goals, the optimization criteria and the various algorithmic techniques used. We identify two primarily distinct types of mesh segmentation, namely parts segmentation and patch seg...

In this paper we introduce a versatile and robust method for analyzing the feature space associated with a given surface. The method is based on the mean-shift operator which was shown to be successful in image and video processing. Its strength stems from the fact that it works in a single space of joint geometry and attributes called the feature-...

Three dimensional shape matching plays an important role in many of today's applications. Nevertheless, shape matching is a difficult problem since there is no unique measure that defines shape similarity and since computing shape distance using various measures is an elaborate task. In this paper we present a new framework for matching shapes, rep...

We present a novel approach for representing and evolving deformable active contours by restricting the movement of the contour vertices to the grid lines of a uniform lattice. This restriction implicitly controls the (re)parameterization of the contour ...

This paper presents an intelligent interface for a personal information management system. The system addresses two main deciencies in personal in- formation retrieval: the cluttering of information in interfaces which creates dif- culties nding data and concentrating on a specic task, and the scattering of related information across different appl...