The vanishing ideal of a set of points, S ⊂ R n , is the set of all polynomials that attain the v... more The vanishing ideal of a set of points, S ⊂ R n , is the set of all polynomials that attain the value of zero on all the points in S. Such ideals can be compactly represented using a small set of polynomials known as generators of the ideal. Here we describe and analyze an efficient procedure that constructs a set of generators of a vanishing ideal. Our procedure is numerically stable, and can be used to find approximately vanishing polynomials. The resulting polynomials capture nonlinear structure in data, and can for example be used within supervised learning. Empirical comparison with kernel methods show that our method constructs more compact classifiers with comparable accuracy.
Surgical simulations with the aid of computers is a topic of increasingly extensive research. Rea... more Surgical simulations with the aid of computers is a topic of increasingly extensive research. Real-time response and interactivity are crucial components of any such system and a major e#ort has been invested in finding ways to improve the performance of existing systems.
IEEE Transactions on Systems Man and Cybernetics Part C (Applications and Reviews)
With the advent of the Internet, it is desirable to interpret and extract useful information from... more With the advent of the Internet, it is desirable to interpret and extract useful information from the Web. One major challenge in Web interface interpretation is to discover the semantic structure underlying a Web interface. Many heuristic approaches have been developed to discover and group semantically related interface objects. However, those approaches cannot solve the problem of nonuniformity satisfactorily and are not able to tag the semantic role of each object. Distinct from existing approaches, this paper develops a robust and formal approach to recovering interface semantics using graph grammars. Because of the distinct capability of spatial specifications in the abstract syntax, the spatial graph grammar (SGG) is selected to perform the semantic grouping and interpretation of segmented screen objects. Instead of analyzing HTML source codes, we apply an efficient image-processing technology to recognize atomic interface objects from the screenshot of an interface and produ...
Proceeding of the eighth ACM symposium on Document engineering - DocEng '08, 2008
We present a document processing method that addresses some of the practical challenges in image ... more We present a document processing method that addresses some of the practical challenges in image enhancement for digital photo album in PDF documents. With the advent of digital offset presses, consumer photo books are becoming increasingly popular, and most such workflows convert the consumer's photos and layout into PDF documents. In order to produce appealing photo albums from consumer photographs,
Surgical simulations with the aid of computers is a topic of increasingly extensive research. Rea... more Surgical simulations with the aid of computers is a topic of increasingly extensive research. Real-time response and interactivity are crucial components of any such system and a major effort has been invested in finding ways to improve the performance of existing systems. In this paper, we propose the use of a new variant of Free Form Deformations that supports discontinuities (DFFD) in complex real time surgical simulations. The proposed scheme can benefit from an a priori or, alternatively, interactive low resolution, physical simulation of the incision procedure that is encoded into the DFFD. The DFFD is then applied to the geometry of the tissue at hand, a two-dimensional skin shape or a three-dimensional volumetric representation, capturing the incision's shape as well as the behavior of the neighborhood geometry over time.
ABSTRACT The recent introduction of programmable Graphics Processing Units (GPUs) has had a treme... more ABSTRACT The recent introduction of programmable Graphics Processing Units (GPUs) has had a tremendous impact on real-time graphics. With their extended flexibility, GPUs can support tasks that go way beyond their originally intended rendering functionality. One domain where GPUs can be applicable is in accelerating geometric modeling applications. In this work, we present a real-time, GPU-based, evaluation scheme for trivariate B-spline functions. These functions are used in the implementation of Freeform Deformations (FFDs), a common global deformation algorithm. Using this deformation scheme, complex objects can be freely warped and animated. The proposed scheme was implemented on contemporary commercially-available graphics cards, achieving interactive rates.
2010 IEEE International Workshop on Multimedia Signal Processing, 2010
In this paper we present a novel method for high quality real-time video enhancement; it improves... more In this paper we present a novel method for high quality real-time video enhancement; it improves the sharpness and the contrast of video streams, and simultaneously suppresses noise. The method is comprised of three main modules: (1) noise analysis, (2) spatial processing, based on a new multi-scale pseudo-bilateral filter, and (3) temporal processing that includes robust motion detection and recursive
2011 IEEE Fifth International Conference on Semantic Computing, 2011
Automatic understanding of GUI (Graphic User Interfaces) is vitally important for applications su... more Automatic understanding of GUI (Graphic User Interfaces) is vitally important for applications such as quality assurance, user monitoring, speech activated devices, automatic generation of GUI for application accessibility, and GUI design. Likewise, automatic understanding of visually structured documents (e.g. PDF files) is vitally important for data mining purposes. Current GUI parsers share two major shortcomings: First, instead of representing the user experience, they are tightly coupled to the underlying object model of the GUI. Second, from a linguistic point of view, they are either too restrictive to describe enough GUIs, or too permissive, in which case, the language structure itself becomes very fragile. We designed and implemented a new GUI parsing language which avoids these problems. It is easy to maintain, robust to changes in the input, and finally -as a computer program -decidable and fast to parse.
Striving for photorealism, texture mapping and its more advanced variations, bump and displacemen... more Striving for photorealism, texture mapping and its more advanced variations, bump and displacement mapping, have all become fundamental tools in computer graphics. Recently, the introduction of programmable graphics hardware has enabled the employment of displacement mapping in real-time applications. While displacement mapping facilitates the actual modification of the underlying geometry, it is constrained by being an injective mapping. Further, it is also limited because it usually maps the geometry of the (low-resolution) smooth base surfaces, typically by displacing their vertices.
Striving for photorealism, texture mapping, and its more advanced variations, bump and displaceme... more Striving for photorealism, texture mapping, and its more advanced variations, bump and displacement mapping, have all become fundamental tools in computer graphics. Recently, the introduction of programmable graphics hardware has enabled the employment of displacement mapping in real-time applications. While displacement mapping facilitates the actual modification of the underlying geometry, it is constrained by being an injective mapping. Further, it
An algorithm for silhouette extraction from volumetric data is presented. Trivariate tensor produ... more An algorithm for silhouette extraction from volumetric data is presented. Trivariate tensor product B-spline functions are used to represent the data. An offline phase that arranges the data in a lookup table is employed to improve the computation time during an interactive session. A subdivision scheme is employed to extract the silhouette curves from an implicit trivariate B-spline function. The produced results are smooth, highquality silhouette curves when compared to voxel-based silhouette extraction schemes.
International Symposium on Technologies for Digital Photo Fulfillment, 2009
a) (b) Figure 1. Image enhancement by the HP Smartstream Photo Enhancement Server. (a) Original i... more a) (b) Figure 1. Image enhancement by the HP Smartstream Photo Enhancement Server. (a) Original image, (b) after processing.
12th Pacific Conference on Computer Graphics and Applications, 2004. PG 2004. Proceedings., 2004
Contemporary deformation tools let designers modify the geometry of deformed models. This approac... more Contemporary deformation tools let designers modify the geometry of deformed models. This approach can be restrictive if the designer wants to incorporate holes or gaps into a model while deforming it into a different shape. This work presents a variant of FFD that would let the designer incorporate iso-parametric discontinuities into the deformation function. The input model is automatically split at these discontinuities, allowing the deformed model to reflect topological discontinuity changes.
The vanishing ideal of a set of points, S ⊂ R n , is the set of all polynomials that attain the v... more The vanishing ideal of a set of points, S ⊂ R n , is the set of all polynomials that attain the value of zero on all the points in S. Such ideals can be compactly represented using a small set of polynomials known as generators of the ideal. Here we describe and analyze an efficient procedure that constructs a set of generators of a vanishing ideal. Our procedure is numerically stable, and can be used to find approximately vanishing polynomials. The resulting polynomials capture nonlinear structure in data, and can for example be used within supervised learning. Empirical comparison with kernel methods show that our method constructs more compact classifiers with comparable accuracy.
Surgical simulations with the aid of computers is a topic of increasingly extensive research. Rea... more Surgical simulations with the aid of computers is a topic of increasingly extensive research. Real-time response and interactivity are crucial components of any such system and a major e#ort has been invested in finding ways to improve the performance of existing systems.
IEEE Transactions on Systems Man and Cybernetics Part C (Applications and Reviews)
With the advent of the Internet, it is desirable to interpret and extract useful information from... more With the advent of the Internet, it is desirable to interpret and extract useful information from the Web. One major challenge in Web interface interpretation is to discover the semantic structure underlying a Web interface. Many heuristic approaches have been developed to discover and group semantically related interface objects. However, those approaches cannot solve the problem of nonuniformity satisfactorily and are not able to tag the semantic role of each object. Distinct from existing approaches, this paper develops a robust and formal approach to recovering interface semantics using graph grammars. Because of the distinct capability of spatial specifications in the abstract syntax, the spatial graph grammar (SGG) is selected to perform the semantic grouping and interpretation of segmented screen objects. Instead of analyzing HTML source codes, we apply an efficient image-processing technology to recognize atomic interface objects from the screenshot of an interface and produ...
Proceeding of the eighth ACM symposium on Document engineering - DocEng '08, 2008
We present a document processing method that addresses some of the practical challenges in image ... more We present a document processing method that addresses some of the practical challenges in image enhancement for digital photo album in PDF documents. With the advent of digital offset presses, consumer photo books are becoming increasingly popular, and most such workflows convert the consumer's photos and layout into PDF documents. In order to produce appealing photo albums from consumer photographs,
Surgical simulations with the aid of computers is a topic of increasingly extensive research. Rea... more Surgical simulations with the aid of computers is a topic of increasingly extensive research. Real-time response and interactivity are crucial components of any such system and a major effort has been invested in finding ways to improve the performance of existing systems. In this paper, we propose the use of a new variant of Free Form Deformations that supports discontinuities (DFFD) in complex real time surgical simulations. The proposed scheme can benefit from an a priori or, alternatively, interactive low resolution, physical simulation of the incision procedure that is encoded into the DFFD. The DFFD is then applied to the geometry of the tissue at hand, a two-dimensional skin shape or a three-dimensional volumetric representation, capturing the incision's shape as well as the behavior of the neighborhood geometry over time.
ABSTRACT The recent introduction of programmable Graphics Processing Units (GPUs) has had a treme... more ABSTRACT The recent introduction of programmable Graphics Processing Units (GPUs) has had a tremendous impact on real-time graphics. With their extended flexibility, GPUs can support tasks that go way beyond their originally intended rendering functionality. One domain where GPUs can be applicable is in accelerating geometric modeling applications. In this work, we present a real-time, GPU-based, evaluation scheme for trivariate B-spline functions. These functions are used in the implementation of Freeform Deformations (FFDs), a common global deformation algorithm. Using this deformation scheme, complex objects can be freely warped and animated. The proposed scheme was implemented on contemporary commercially-available graphics cards, achieving interactive rates.
2010 IEEE International Workshop on Multimedia Signal Processing, 2010
In this paper we present a novel method for high quality real-time video enhancement; it improves... more In this paper we present a novel method for high quality real-time video enhancement; it improves the sharpness and the contrast of video streams, and simultaneously suppresses noise. The method is comprised of three main modules: (1) noise analysis, (2) spatial processing, based on a new multi-scale pseudo-bilateral filter, and (3) temporal processing that includes robust motion detection and recursive
2011 IEEE Fifth International Conference on Semantic Computing, 2011
Automatic understanding of GUI (Graphic User Interfaces) is vitally important for applications su... more Automatic understanding of GUI (Graphic User Interfaces) is vitally important for applications such as quality assurance, user monitoring, speech activated devices, automatic generation of GUI for application accessibility, and GUI design. Likewise, automatic understanding of visually structured documents (e.g. PDF files) is vitally important for data mining purposes. Current GUI parsers share two major shortcomings: First, instead of representing the user experience, they are tightly coupled to the underlying object model of the GUI. Second, from a linguistic point of view, they are either too restrictive to describe enough GUIs, or too permissive, in which case, the language structure itself becomes very fragile. We designed and implemented a new GUI parsing language which avoids these problems. It is easy to maintain, robust to changes in the input, and finally -as a computer program -decidable and fast to parse.
Striving for photorealism, texture mapping and its more advanced variations, bump and displacemen... more Striving for photorealism, texture mapping and its more advanced variations, bump and displacement mapping, have all become fundamental tools in computer graphics. Recently, the introduction of programmable graphics hardware has enabled the employment of displacement mapping in real-time applications. While displacement mapping facilitates the actual modification of the underlying geometry, it is constrained by being an injective mapping. Further, it is also limited because it usually maps the geometry of the (low-resolution) smooth base surfaces, typically by displacing their vertices.
Striving for photorealism, texture mapping, and its more advanced variations, bump and displaceme... more Striving for photorealism, texture mapping, and its more advanced variations, bump and displacement mapping, have all become fundamental tools in computer graphics. Recently, the introduction of programmable graphics hardware has enabled the employment of displacement mapping in real-time applications. While displacement mapping facilitates the actual modification of the underlying geometry, it is constrained by being an injective mapping. Further, it
An algorithm for silhouette extraction from volumetric data is presented. Trivariate tensor produ... more An algorithm for silhouette extraction from volumetric data is presented. Trivariate tensor product B-spline functions are used to represent the data. An offline phase that arranges the data in a lookup table is employed to improve the computation time during an interactive session. A subdivision scheme is employed to extract the silhouette curves from an implicit trivariate B-spline function. The produced results are smooth, highquality silhouette curves when compared to voxel-based silhouette extraction schemes.
International Symposium on Technologies for Digital Photo Fulfillment, 2009
a) (b) Figure 1. Image enhancement by the HP Smartstream Photo Enhancement Server. (a) Original i... more a) (b) Figure 1. Image enhancement by the HP Smartstream Photo Enhancement Server. (a) Original image, (b) after processing.
12th Pacific Conference on Computer Graphics and Applications, 2004. PG 2004. Proceedings., 2004
Contemporary deformation tools let designers modify the geometry of deformed models. This approac... more Contemporary deformation tools let designers modify the geometry of deformed models. This approach can be restrictive if the designer wants to incorporate holes or gaps into a model while deforming it into a different shape. This work presents a variant of FFD that would let the designer incorporate iso-parametric discontinuities into the deformation function. The input model is automatically split at these discontinuities, allowing the deformed model to reflect topological discontinuity changes.
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Papers by Sagi Schein