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Marco Agus

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SACHITHANANDAM.R R

Anna University

Duke University

Alonzo C Addison

University of California, Berkeley

Larissa Scantamburlo

UNIVILLE

STMM MMTC YOGYAKARTA

University of York

University of Science and Technology of China

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Papers by Marco Agus

Creating and Presenting Real and Artificial Visual Stimuli for the Neurophysiological Investigation of the Observation/Execution Matching System

Recent neurophysiological experiments have shown that the visual stimuli that trigger a particula... more Recent neurophysiological experiments have shown that the visual stimuli that trigger a particular kind of neurons located in the ventral premo- tor cortex of monkeys and humans are very selective. These mirror neurons are activated when the hand of another individual interacts with an objects but are not activated when the actions, identical in purpose, are made by manipulated mechanical

An Integrated Environment for Stereoscopic Acquisition, Off-line 3D Elaboration, and Visual Presentation of Biological Actions

We present an integrated environment for stereoscopic acquisition, off-line 3D elaboration, and v... more We present an integrated environment for stereoscopic acquisition, off-line 3D elaboration, and visual presentation of biological hand actions. The system is used in neurophysiological experiments aimed at the investigation of the parameters of the external stimuli that mirror neurons visually extract and match on their movement related activity.

Hierarchical Higher Order Face Cluster Radiosity

We present an algorithm for simulating diffuse interreflection in scenes composed,of highly tesse... more We present an algorithm for simulating diffuse interreflection in scenes composed,of highly tessellated objects. The method,is a higher order extension of the face cluster radiosity technique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order bases with a modified progressive shooting iteration to rapidly produce visually continuous solutions with limited memory,requirements. The output of the method,is a

Exploring Virtual Prototypes Using Time-Critical Multiresolution Rendering

We present an application of our time-critical multiresolution rendering algorithm to the visual ... more We present an application of our time-critical multiresolution rendering algorithm to the visual and possibly collaborative exploration of large digital mock-ups. Our technique relies upon a scene description in which objects are represented as multiresolution meshes. We perform a constrained optimization at each frame to choose the resolution of each potentially visible object that generates the best quality image while

Hardware-Accelerated Dynamic Volume Rendering for RealñTime Surgical Simulation

We developed a direct volume rendering technique, that supports low latency real time visual feed... more We developed a direct volume rendering technique, that supports low latency real time visual feedback in parallel with physical simulation on commod- ity graphics platforms. In our approach, a fast approximation of the diffuse shad- ing equation is computed on the y by the graphics pipe-line directly from the scalar data. We do this by exploiting the possibilities offered by

FOX

Proceedings of the 10th International Conference on Virtual Reality Continuum and Its Applications in Industry - VRCAI '11, 2011

Implementation and evaluation of an interactive volume visualization system on a lightfield display

ABSTRACT

Mastoidectomy simulation with combined visual and haptic feedback

Studies in health technology and informatics, 2002

Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this... more Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this paper we describe our preliminary results in the realization of a virtual reality mastoidectomy simulator. Our system is designed to work on patient-specific volumetric object models directly derived from 3D CT and MRI images. The paper summarizes the detailed task analysis performed in order to define the system requirements, introduces the architecture of the prototype simulator, and discusses the initial feedback received from selected end users.

Tracking the movement of surgical tools in a virtual temporal bone dissection simulator

by Marco Agus and Andrea Giachetti

In this paper we present the current state of our research on simulation of temporal bone surgica... more In this paper we present the current state of our research on simulation of temporal bone surgical procedures. We describe the results of tests performed on a virtual surgical training system for middle ear surgery. The work is aimed to demonstrate how expert surgeons and trainees can effectively use the system for training and assessment purposes. Preliminary kinematic and dynamic analysis of simulated mastoidectomy sessions are presented. The simulation system used is characterized by a haptic component exploiting a bone-burr contact and erosion simulation model, a direct volume rendering module as well as a timecritical particle system to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.

Hierarchical Higher Order sFace Cluster Radiosity for Global Illumination Walkthroughs of Complex Non-Diffuse Environments

Computer Graphics Forum, 2003

We present an algorithm for simulating global illumination in scenes composed of highly tessellat... more We present an algorithm for simulating global illumination in scenes composed of highly tessellated objects with diffuse or moderately glossy reflectance. The solution method is a higher order extension of the face cluster ra- diosity technique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order bases with a modified progressive shooting iteration to rapidly produce visually continuous solutions

Automatic geometric calibration of projector-based light field displays

by Marco Agus and Alberto Jaspe

ABSTRACT Continuous multiview (light-field) projection-based displays employ an array of projecto... more ABSTRACT Continuous multiview (light-field) projection-based displays employ an array of projectors, mirrors, and a selectively transmissive screen to produce a light field. By appropriately modeling the display geometry, the light beams can emulate the emission from physical objects at fixed spatial locations, providing multiple freely moving viewers the illusion of interacting with floating objects. This paper presents a novel calibration method for this class of displays using a single uncalibrated camera and four fiducial markers. Calibration starts from a simple parametric description of the display layout. First, individual projectors are calibrated through parametric optimization of an idealized pinhole model. Then, the overall display and projector parameterization is globally optimized. Finally, independently for each projector, remaining errors are corrected through a rational 2D warping function. The final parameters are available to rendering engines to quickly compute forward and backward projections. The technique is demonstrated in the calibration of a large-scale horizontal-parallax-only 35MPixels light field display.

Practical line rasterization for multi-resolution textures

by Marco Agus and Alberto Jaspe

SOAR: Stochastic Optimization for Affine global point set Registration

by Marco Agus and Alberto Jaspe

We introduce a stochastic algorithm for pairwise affine registration of partially overlapping 3D ... more We introduce a stochastic algorithm for pairwise affine registration of partially overlapping 3D point clouds with unknown point correspondences. The algorithm recovers the globally optimal scale, rotation, and translation alignment parameters and is applicable in a variety of difficult settings, including very sparse, noisy, and outlierridden datasets that do not permit the computation of local descriptors. The technique is based on a stochastic approach for the global optimization of an alignment error function robust to noise and resistant to outliers. At each optimization step, it alternates between stochastically visiting a generalized BSP-tree representation of the current solution landscape to select a promising transformation, finding point-to-point correspondences using a GPU-accelerated technique, and incorporating new error values in the BSP tree. In contrast to previous work, instead of simply constructing the tree by guided random sampling, we exploit the problem structure through a low-cost local minimization process based on analytically solving absolute orientation problems using the current correspondences. We demonstrate the quality and performance of our method on a variety of large point sets with different scales, resolutions, and noise characteristics.

Interactive mapping of indoor building structures through mobile devices

ABSTRACT We present a practical system to map and reconstruct multi-room indoor structures using ... more ABSTRACT We present a practical system to map and reconstruct multi-room indoor structures using the sensors commonly available in commodity smartphones. Our approach combines and extends state-of-the-art results to automatically generate floor plans scaled to real-world metric dimensions and to reconstruct scenes not necessarily limited to the Manhattan World assumption. In contrast to previous works, our method introduces an interactive method based on statistical indicators for refining wall orientations and a specialized merging algorithm for building the final rooms shape. The low CPU cost of the method makes it possible to support full execution by commodity smartphones, without the need of connecting them to a compute server. We demonstrate the effectiveness of our technique on a variety of multi-room indoor scenes, achieving remarkably better results than previous approaches.

Exploring virtual prototypes using time-critical rendering

Abstract. We present an application of our time-critical multiresolution rendering algorithm to t... more Abstract. We present an application of our time-critical multiresolution rendering algorithm to the visual and possibly collaborative exploration of large digital mock-ups. Our technique relies upon a scene description in which objects are represented as multiresolution meshes. We perform a constrained optimization at each frame to choose the resolution of each potentially visible object that generates the best quality image while meeting timing constraints. We present numerical and pictorial results of the experiments performed that ...

IERAPSI. Surgical simulator software kernel

by Marco Agus and Andrea Giachetti

IERAPSI. Petrous bone surgical simulation platform

by Marco Agus and Andrea Giachetti

Haptic simulation of bone dissection

by Marco Agus and Andrea Giachetti

Bone dissection is an important component of many surgical procedures. We discuss a haptic implem... more Bone dissection is an important component of many surgical procedures. We discuss a haptic implementation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. We use a physically motivated model to describe the burr-bone interaction process. The model includes haptic forces evaluation, the bone erosion process and the resulting debris. The current implementation, directly operating on a voxel discretization of patient-specific 3D imaging data, is efficient enough to provide real-time feedback on a low end multi processing PC platform.

HuMoRS: huge models mobile rendering system

ABSTRACT We present HuMoRS, a networked 3D graphics system for interactively streaming and explor... more ABSTRACT We present HuMoRS, a networked 3D graphics system for interactively streaming and exploring massive 3D mesh models on mobile devices. The system integrates a networked architecture for adaptive on-device rendering of multiresolution surfaces with a simple and effective interactive camera controller customized for touch-enabled mobile devices. During interaction, knowledge of the currently rendered scene is exploited to automatically center a rotation pivot and to propose context-dependent precomputed viewpoints. Both the object of interest and the viewpoint database are resident on a web server and adaptive transmission is demonstrated over wireless and phone connections in a Cultural Heritage application for the exploration of sub-millimetric colored reconstructions of stone statues. We report also on a preliminary user-study comparing the performances of our camera navigation method with respect to the most popular Virtual TrackBall implementations, with and without pivoting.

IsoCam: Interactive visual exploration of massive cultural heritage models on large projection setups

ABSTRACT We introduce a novel user interface and system for exploring extremely detailed 3D model... more ABSTRACT We introduce a novel user interface and system for exploring extremely detailed 3D models in a museum setting. 3D models and associated information are presented on a large projection surface controlled by a touch-enabled surface placed at a suitable distance in front of it. Our indirect user interface, dubbed IsoCam, combines an object-aware interactive camera controller with an interactive point-of-interest selector and is implemented within a scalable implementation based on multiresolution structures shared between the rendering and user interaction subsystems. The collision-free camera controller automatically supports the smooth transition from orbiting to proximal navigation, by exploiting a distance-field representation of the 3D object. The point-of-interest selector exploits a specialized view similarity computation to propose a few nearby easily reachable interesting 3D views from a large database, move the camera to the user-selected point of interest, and provide extra information through overlaid annotations of the target view. The capabilities of our approach have been demonstrated in a public event attended by thousands of people, which were offered the possibility to explore sub-millimetric reconstructions of 38 stone statues of the Mont&#39;e Prama Nuragic complex, depicting larger-than-life human figures, and small models of prehistoric Nuraghe (cone-shaped stone towers). A follow-up of this work, using 2.5m-high projection screens, is now included in permanent exhibitions at two Archeological Museums. Results of a thorough user evaluation, involving quantitative and subjective measurements, are discussed.

Creating and Presenting Real and Artificial Visual Stimuli for the Neurophysiological Investigation of the Observation/Execution Matching System

Recent neurophysiological experiments have shown that the visual stimuli that trigger a particula... more Recent neurophysiological experiments have shown that the visual stimuli that trigger a particular kind of neurons located in the ventral premo- tor cortex of monkeys and humans are very selective. These mirror neurons are activated when the hand of another individual interacts with an objects but are not activated when the actions, identical in purpose, are made by manipulated mechanical

An Integrated Environment for Stereoscopic Acquisition, Off-line 3D Elaboration, and Visual Presentation of Biological Actions

We present an integrated environment for stereoscopic acquisition, off-line 3D elaboration, and v... more We present an integrated environment for stereoscopic acquisition, off-line 3D elaboration, and visual presentation of biological hand actions. The system is used in neurophysiological experiments aimed at the investigation of the parameters of the external stimuli that mirror neurons visually extract and match on their movement related activity.

Hierarchical Higher Order Face Cluster Radiosity

We present an algorithm for simulating diffuse interreflection in scenes composed,of highly tesse... more We present an algorithm for simulating diffuse interreflection in scenes composed,of highly tessellated objects. The method,is a higher order extension of the face cluster radiosity technique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order bases with a modified progressive shooting iteration to rapidly produce visually continuous solutions with limited memory,requirements. The output of the method,is a

Exploring Virtual Prototypes Using Time-Critical Multiresolution Rendering

We present an application of our time-critical multiresolution rendering algorithm to the visual ... more We present an application of our time-critical multiresolution rendering algorithm to the visual and possibly collaborative exploration of large digital mock-ups. Our technique relies upon a scene description in which objects are represented as multiresolution meshes. We perform a constrained optimization at each frame to choose the resolution of each potentially visible object that generates the best quality image while

Hardware-Accelerated Dynamic Volume Rendering for RealñTime Surgical Simulation

We developed a direct volume rendering technique, that supports low latency real time visual feed... more We developed a direct volume rendering technique, that supports low latency real time visual feedback in parallel with physical simulation on commod- ity graphics platforms. In our approach, a fast approximation of the diffuse shad- ing equation is computed on the y by the graphics pipe-line directly from the scalar data. We do this by exploiting the possibilities offered by

FOX

Proceedings of the 10th International Conference on Virtual Reality Continuum and Its Applications in Industry - VRCAI '11, 2011

Implementation and evaluation of an interactive volume visualization system on a lightfield display

ABSTRACT

Mastoidectomy simulation with combined visual and haptic feedback

Studies in health technology and informatics, 2002

Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this... more Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this paper we describe our preliminary results in the realization of a virtual reality mastoidectomy simulator. Our system is designed to work on patient-specific volumetric object models directly derived from 3D CT and MRI images. The paper summarizes the detailed task analysis performed in order to define the system requirements, introduces the architecture of the prototype simulator, and discusses the initial feedback received from selected end users.

Tracking the movement of surgical tools in a virtual temporal bone dissection simulator

by Marco Agus and Andrea Giachetti

In this paper we present the current state of our research on simulation of temporal bone surgica... more In this paper we present the current state of our research on simulation of temporal bone surgical procedures. We describe the results of tests performed on a virtual surgical training system for middle ear surgery. The work is aimed to demonstrate how expert surgeons and trainees can effectively use the system for training and assessment purposes. Preliminary kinematic and dynamic analysis of simulated mastoidectomy sessions are presented. The simulation system used is characterized by a haptic component exploiting a bone-burr contact and erosion simulation model, a direct volume rendering module as well as a timecritical particle system to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.

Hierarchical Higher Order sFace Cluster Radiosity for Global Illumination Walkthroughs of Complex Non-Diffuse Environments

Computer Graphics Forum, 2003

We present an algorithm for simulating global illumination in scenes composed of highly tessellat... more We present an algorithm for simulating global illumination in scenes composed of highly tessellated objects with diffuse or moderately glossy reflectance. The solution method is a higher order extension of the face cluster ra- diosity technique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order bases with a modified progressive shooting iteration to rapidly produce visually continuous solutions

Automatic geometric calibration of projector-based light field displays

by Marco Agus and Alberto Jaspe

ABSTRACT Continuous multiview (light-field) projection-based displays employ an array of projecto... more ABSTRACT Continuous multiview (light-field) projection-based displays employ an array of projectors, mirrors, and a selectively transmissive screen to produce a light field. By appropriately modeling the display geometry, the light beams can emulate the emission from physical objects at fixed spatial locations, providing multiple freely moving viewers the illusion of interacting with floating objects. This paper presents a novel calibration method for this class of displays using a single uncalibrated camera and four fiducial markers. Calibration starts from a simple parametric description of the display layout. First, individual projectors are calibrated through parametric optimization of an idealized pinhole model. Then, the overall display and projector parameterization is globally optimized. Finally, independently for each projector, remaining errors are corrected through a rational 2D warping function. The final parameters are available to rendering engines to quickly compute forward and backward projections. The technique is demonstrated in the calibration of a large-scale horizontal-parallax-only 35MPixels light field display.

Practical line rasterization for multi-resolution textures

by Marco Agus and Alberto Jaspe

SOAR: Stochastic Optimization for Affine global point set Registration

by Marco Agus and Alberto Jaspe

We introduce a stochastic algorithm for pairwise affine registration of partially overlapping 3D ... more We introduce a stochastic algorithm for pairwise affine registration of partially overlapping 3D point clouds with unknown point correspondences. The algorithm recovers the globally optimal scale, rotation, and translation alignment parameters and is applicable in a variety of difficult settings, including very sparse, noisy, and outlierridden datasets that do not permit the computation of local descriptors. The technique is based on a stochastic approach for the global optimization of an alignment error function robust to noise and resistant to outliers. At each optimization step, it alternates between stochastically visiting a generalized BSP-tree representation of the current solution landscape to select a promising transformation, finding point-to-point correspondences using a GPU-accelerated technique, and incorporating new error values in the BSP tree. In contrast to previous work, instead of simply constructing the tree by guided random sampling, we exploit the problem structure through a low-cost local minimization process based on analytically solving absolute orientation problems using the current correspondences. We demonstrate the quality and performance of our method on a variety of large point sets with different scales, resolutions, and noise characteristics.

Interactive mapping of indoor building structures through mobile devices

ABSTRACT We present a practical system to map and reconstruct multi-room indoor structures using ... more ABSTRACT We present a practical system to map and reconstruct multi-room indoor structures using the sensors commonly available in commodity smartphones. Our approach combines and extends state-of-the-art results to automatically generate floor plans scaled to real-world metric dimensions and to reconstruct scenes not necessarily limited to the Manhattan World assumption. In contrast to previous works, our method introduces an interactive method based on statistical indicators for refining wall orientations and a specialized merging algorithm for building the final rooms shape. The low CPU cost of the method makes it possible to support full execution by commodity smartphones, without the need of connecting them to a compute server. We demonstrate the effectiveness of our technique on a variety of multi-room indoor scenes, achieving remarkably better results than previous approaches.

Exploring virtual prototypes using time-critical rendering

Abstract. We present an application of our time-critical multiresolution rendering algorithm to t... more Abstract. We present an application of our time-critical multiresolution rendering algorithm to the visual and possibly collaborative exploration of large digital mock-ups. Our technique relies upon a scene description in which objects are represented as multiresolution meshes. We perform a constrained optimization at each frame to choose the resolution of each potentially visible object that generates the best quality image while meeting timing constraints. We present numerical and pictorial results of the experiments performed that ...

IERAPSI. Surgical simulator software kernel

by Marco Agus and Andrea Giachetti

IERAPSI. Petrous bone surgical simulation platform

by Marco Agus and Andrea Giachetti

Haptic simulation of bone dissection

by Marco Agus and Andrea Giachetti

Bone dissection is an important component of many surgical procedures. We discuss a haptic implem... more Bone dissection is an important component of many surgical procedures. We discuss a haptic implementation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. We use a physically motivated model to describe the burr-bone interaction process. The model includes haptic forces evaluation, the bone erosion process and the resulting debris. The current implementation, directly operating on a voxel discretization of patient-specific 3D imaging data, is efficient enough to provide real-time feedback on a low end multi processing PC platform.

HuMoRS: huge models mobile rendering system

ABSTRACT We present HuMoRS, a networked 3D graphics system for interactively streaming and explor... more ABSTRACT We present HuMoRS, a networked 3D graphics system for interactively streaming and exploring massive 3D mesh models on mobile devices. The system integrates a networked architecture for adaptive on-device rendering of multiresolution surfaces with a simple and effective interactive camera controller customized for touch-enabled mobile devices. During interaction, knowledge of the currently rendered scene is exploited to automatically center a rotation pivot and to propose context-dependent precomputed viewpoints. Both the object of interest and the viewpoint database are resident on a web server and adaptive transmission is demonstrated over wireless and phone connections in a Cultural Heritage application for the exploration of sub-millimetric colored reconstructions of stone statues. We report also on a preliminary user-study comparing the performances of our camera navigation method with respect to the most popular Virtual TrackBall implementations, with and without pivoting.

IsoCam: Interactive visual exploration of massive cultural heritage models on large projection setups

ABSTRACT We introduce a novel user interface and system for exploring extremely detailed 3D model... more ABSTRACT We introduce a novel user interface and system for exploring extremely detailed 3D models in a museum setting. 3D models and associated information are presented on a large projection surface controlled by a touch-enabled surface placed at a suitable distance in front of it. Our indirect user interface, dubbed IsoCam, combines an object-aware interactive camera controller with an interactive point-of-interest selector and is implemented within a scalable implementation based on multiresolution structures shared between the rendering and user interaction subsystems. The collision-free camera controller automatically supports the smooth transition from orbiting to proximal navigation, by exploiting a distance-field representation of the 3D object. The point-of-interest selector exploits a specialized view similarity computation to propose a few nearby easily reachable interesting 3D views from a large database, move the camera to the user-selected point of interest, and provide extra information through overlaid annotations of the target view. The capabilities of our approach have been demonstrated in a public event attended by thousands of people, which were offered the possibility to explore sub-millimetric reconstructions of 38 stone statues of the Mont&#39;e Prama Nuragic complex, depicting larger-than-life human figures, and small models of prehistoric Nuraghe (cone-shaped stone towers). A follow-up of this work, using 2.5m-high projection screens, is now included in permanent exhibitions at two Archeological Museums. Results of a thorough user evaluation, involving quantitative and subjective measurements, are discussed.