2007
Conference article
Open Access
Extending geometrical acoustics to highy detailed architectural environments
Tsingos N, Dachsbacher C, Lefebvre S, Dellepiane M
Geometrical acoustics (GA) is a widely used approximation for simulating sound propagation in virtual 3D environments. However, GA is a high-frequency approximation and therefore very detailed models, containing features small compared to audible wavelengths, may fall outside its validity domain. Including finer geometrical details might actually degrade the quality of the simulation, as supported by a number of previous studies. Furthermore, the cost of running GA-based simulations significantly increases with the geometrical complexity. In this paper, we propose an extension to GA for highly detailed environments. In particular, we pre-compute a representation of the scattering behavior off complex geometry using finite element techniques. We then use this representation within classical GA frameworks, such as radiosity or ray-casting, to compute impulse responses and auralize the corresponding acoustical effects.
Tsingos N, Dachsbacher C, Lefebvre S, Dellepiane M
Geometrical acoustics (GA) is a widely used approximation for simulating sound propagation in virtual 3D environments. However, GA is a high-frequency approximation and therefore very detailed models, containing features small compared to audible wavelengths, may fall outside its validity domain. Including finer geometrical details might actually degrade the quality of the simulation, as supported by a number of previous studies. Furthermore, the cost of running GA-based simulations significantly increases with the geometrical complexity. In this paper, we propose an extension to GA for highly detailed environments. In particular, we pre-compute a representation of the scattering behavior off complex geometry using finite element techniques. We then use this representation within classical GA frameworks, such as radiosity or ray-casting, to compute impulse responses and auralize the corresponding acoustical effects.
See at:
CNR IRIS 
| www.sea-acustica.es | CNR IRIS 
2007
Conference article
Restricted
Instant Sound Scattering
Tsingos N, Dachsbacher C, Lefevbre S, Dellepiane M
Real-time sound rendering engines often render occlusion and early sound reflection effects using geometrical techniques such as ray or beam tracing. They can only achieve interactive rendering for environments of low local complexity resulting in crude effects which can degrade the sense of immersion. However, surface detail or complex dynamic geometry has a strong influence on sound propagation and the resulting auditory perception. This paper focuses on high-quality modeling of first-order sound scattering. Based on a surface-integral formulation and the Kirchhoff approximation, we propose an efficient evaluation of scattering effects, including both diffraction and reflection, that leverages programmable graphics hardware for dense sampling of complex surfaces. We evaluate possible surface simplification techniques and show that combined normal and displacement maps can be successfully used for audio scattering calculations. We present an auralization framework that can render scattering effects interactively thus providing a more compelling experience. We demonstrate that, while only considering first order phenomena, our approach can provide realistic results for a number of practical interactive applications. It can also process highly detailed models containing millions of unorganized triangles in minutes, generating high-quality scattering filters. Resulting simulations compare well with on-site recordings showing that the Kirchhoff approximation can be used for complex scattering problems.
Tsingos N, Dachsbacher C, Lefevbre S, Dellepiane M
Real-time sound rendering engines often render occlusion and early sound reflection effects using geometrical techniques such as ray or beam tracing. They can only achieve interactive rendering for environments of low local complexity resulting in crude effects which can degrade the sense of immersion. However, surface detail or complex dynamic geometry has a strong influence on sound propagation and the resulting auditory perception. This paper focuses on high-quality modeling of first-order sound scattering. Based on a surface-integral formulation and the Kirchhoff approximation, we propose an efficient evaluation of scattering effects, including both diffraction and reflection, that leverages programmable graphics hardware for dense sampling of complex surfaces. We evaluate possible surface simplification techniques and show that combined normal and displacement maps can be successfully used for audio scattering calculations. We present an auralization framework that can render scattering effects interactively thus providing a more compelling experience. We demonstrate that, while only considering first order phenomena, our approach can provide realistic results for a number of practical interactive applications. It can also process highly detailed models containing millions of unorganized triangles in minutes, generating high-quality scattering filters. Resulting simulations compare well with on-site recordings showing that the Kirchhoff approximation can be used for complex scattering problems.
See at:
diglib.eg.org | CNR IRIS | CNR IRIS
2007
Other
Metadata Only Access
Investigation of auditory-visual integration in VR Environments
Nguyen K, Dellepiane M, Viauddelmon I, Warusfel O
Investigating the time and spatial constraints under which visual and auditory stimuli are perceived as a unique percept or as spatially coincident has been a topic of numerous researches. However, these findings have been derived up to now in extremely simplified stimulation context consisting in the combination of elementary auditory and visual stimuli usually displayed in dark and anechoic conditions. The present experiment is conducted in a VR environment using a passive stereoscopic display and binaural audio rendering. Subjects have to indicate the point of subjective spatial alignment (PSSA) between a horizontally moving visual stimulus that crosses the direction of a stationary sound. Auditory stimuli are displayed on headphones using individualized head-related transfer functions and the visual stimulus is integrated in a visual background texture in order to convey visual perspective. Two types of audio stimuli are used to evaluate the influence of auditory localisation acuity on the auditory-visual integration: periodic white noise bursts providing optimal localisation cues and periodic 1kHz tone bursts. The present study will indicate whether previous findings (Lewald et al., Behavioural Brain Research, 2001) still hold in more complex audio-visual contexts such as those offered by cutting edge VR environments.
Nguyen K, Dellepiane M, Viauddelmon I, Warusfel O
Investigating the time and spatial constraints under which visual and auditory stimuli are perceived as a unique percept or as spatially coincident has been a topic of numerous researches. However, these findings have been derived up to now in extremely simplified stimulation context consisting in the combination of elementary auditory and visual stimuli usually displayed in dark and anechoic conditions. The present experiment is conducted in a VR environment using a passive stereoscopic display and binaural audio rendering. Subjects have to indicate the point of subjective spatial alignment (PSSA) between a horizontally moving visual stimulus that crosses the direction of a stationary sound. Auditory stimuli are displayed on headphones using individualized head-related transfer functions and the visual stimulus is integrated in a visual background texture in order to convey visual perspective. Two types of audio stimuli are used to evaluate the influence of auditory localisation acuity on the auditory-visual integration: periodic white noise bursts providing optimal localisation cues and periodic 1kHz tone bursts. The present study will indicate whether previous findings (Lewald et al., Behavioural Brain Research, 2001) still hold in more complex audio-visual contexts such as those offered by cutting edge VR environments.
See at:
CNR IRIS
2006
Software
Metadata Only Access
TexAlign
Ganovelli M, Dellepiane M
Il pacchetto software permette di allineare un set di fotografie digitali ad un modello 3D stimando opportunamente i parametri della camera.
Ganovelli M, Dellepiane M
Il pacchetto software permette di allineare un set di fotografie digitali ad un modello 3D stimando opportunamente i parametri della camera.
See at:
CNR IRIS
2013
Conference article
Restricted
Scene analysis for automatic object segmentation and view suggestion in assisted multi-view stereo reconstruction
Cavarretta E, Dellepiane M, Cignoni P Scopigno R
Multi-view stereo reconstruction methods can provide impressive results in a number of applications. Nevertheless, when trying to apply the state-of-the-art methods in the case of a more structured 3D acquisition, the lack of feedback on the quality of the reconstruction during the photo shooting can be problematic. In this poster we present a framework for the assisted reconstruction from images of real objects. In particular, the framework is able to separate the object of interest from the background and suggests missing points of view to the user, without any previous knowledge of the shape of the scene and the acquisition path. This is obtained by analyzing the sparse reconstruction and the connection between the reconstructed points and the input images. The framework has been tested on a variety of practical cases, and it has proved to be effective not only to obtain more complete reconstructions, but also to reduce the number of images needed and the processing time for dense reconstruction.
Cavarretta E, Dellepiane M, Cignoni P Scopigno R
Multi-view stereo reconstruction methods can provide impressive results in a number of applications. Nevertheless, when trying to apply the state-of-the-art methods in the case of a more structured 3D acquisition, the lack of feedback on the quality of the reconstruction during the photo shooting can be problematic. In this poster we present a framework for the assisted reconstruction from images of real objects. In particular, the framework is able to separate the object of interest from the background and suggests missing points of view to the user, without any previous knowledge of the shape of the scene and the acquisition path. This is obtained by analyzing the sparse reconstruction and the connection between the reconstructed points and the input images. The framework has been tested on a variety of practical cases, and it has proved to be effective not only to obtain more complete reconstructions, but also to reduce the number of images needed and the processing time for dense reconstruction.
2014
Book
Restricted
Introduction to special issue on interacting with the past
Hachet M, Dellepiane M
The current special issue joins together such examples of fascinating works dedicated to interaction with cultural heritage covering a wide range of possible examples.Source: ACM JOURNAL ON COMPUTING AND CULTURAL HERITAGE
Hachet M, Dellepiane M
The current special issue joins together such examples of fascinating works dedicated to interaction with cultural heritage covering a wide range of possible examples.Source: ACM JOURNAL ON COMPUTING AND CULTURAL HERITAGE
See at:
dl.acm.org | CNR IRIS | CNR IRIS
2014
Conference article
Metadata Only Access
Site-specific art and 3D: an example of spatial analysis and reconstruction
Dellepiane M, De Matteis M
Site-specific art is a concept that goes back to the beginning of human race: the works of art were often created by artists taking into account not only their shape and appearance, but also the context in which they would be put. For this reason, moving the artifacts from its original placement (or the changes which happen around it) tend to decrease its impact, and possibly weaken its potentials. Site-specific art is a very powerful concept also for contemporary artists. This paper focuses on the analysis of L.O.V.E., a sculpture from the controversial artist Maurizio Cattelan. Cattelan donated the sculpture to Milano, under the condition that it should not be moved from its original place (in front of Milano Stock Exchange). The aim of the paper is to use 3D reconstruction techniques to show and analyse the monument, stressing its relation with the context around it. A multi-view stereo matching campaign was perfomed to have an accurate reconstruction of the context, then the photos provided by the community were integrated in the reconstruction to show the "point of view" of the people. These data provide interesting indications about the aims of the authors, and they provide additional material for the interpretation of the work of artProject(s): V-MUST.NET
Dellepiane M, De Matteis M
Site-specific art is a concept that goes back to the beginning of human race: the works of art were often created by artists taking into account not only their shape and appearance, but also the context in which they would be put. For this reason, moving the artifacts from its original placement (or the changes which happen around it) tend to decrease its impact, and possibly weaken its potentials. Site-specific art is a very powerful concept also for contemporary artists. This paper focuses on the analysis of L.O.V.E., a sculpture from the controversial artist Maurizio Cattelan. Cattelan donated the sculpture to Milano, under the condition that it should not be moved from its original place (in front of Milano Stock Exchange). The aim of the paper is to use 3D reconstruction techniques to show and analyse the monument, stressing its relation with the context around it. A multi-view stereo matching campaign was perfomed to have an accurate reconstruction of the context, then the photos provided by the community were integrated in the reconstruction to show the "point of view" of the people. These data provide interesting indications about the aims of the authors, and they provide additional material for the interpretation of the work of artProject(s): V-MUST.NET
See at:
CNR IRIS
2006
Journal article
Restricted
Visualization of colour information on highly detailed 3D models
Dellepiane M, Callieri M
The evolution of technology and important advances in the field of visualization of huge 3D datasets mean that it is now possible to acquire and display detailed 3D models. However, in order to achieve a completely realistic result, high quality colour information must be added to the geometric structure.Source: ERCIM NEWS, vol. 67, pp. 53-54
Dellepiane M, Callieri M
The evolution of technology and important advances in the field of visualization of huge 3D datasets mean that it is now possible to acquire and display detailed 3D models. However, in order to achieve a completely realistic result, high quality colour information must be added to the geometric structure.Source: ERCIM NEWS, vol. 67, pp. 53-54
2005
Other
Open Access
Extracting meta-information from 3-dimensional shapes with protégé
Borgo R, Dellepiane M, Cignoni P, Papaleo L, Spagnuolo M
Connection between material objects and human perceptions conveys a varied amount of information by means not only of pure registrable data but also concepts with a formalizable objective meaning. Thanks to the advancing of current technology acquisition and registration of such data is become a daily routine. An incredible amount of tool exists as support to the visualization of phenomena in terms of their appearance and attributes, not an equally wide range of tool is available to interact with the semantic information conveyed by such phenomena. To address this issue we developed a tool called TriMeshInfo that aims at supporting the process of switching between the three basic levels of shape-knowledge representation: geometric, structural and semantic.
Borgo R, Dellepiane M, Cignoni P, Papaleo L, Spagnuolo M
Connection between material objects and human perceptions conveys a varied amount of information by means not only of pure registrable data but also concepts with a formalizable objective meaning. Thanks to the advancing of current technology acquisition and registration of such data is become a daily routine. An incredible amount of tool exists as support to the visualization of phenomena in terms of their appearance and attributes, not an equally wide range of tool is available to interact with the semantic information conveyed by such phenomena. To address this issue we developed a tool called TriMeshInfo that aims at supporting the process of switching between the three basic levels of shape-knowledge representation: geometric, structural and semantic.
See at:
CNR IRIS | ISTI Repository | vcg.isti.cnr.it | CNR IRIS
2011
Conference article
Restricted
Improving high-speed scanning systems by photometric stereo
Larue F, Dellepiane M, Scopigno R
High-speed scanning systems can be extremely valuable for Cultural Heritage applications, especially when large collections of small objects have to be acquired. However, fine details may not be acquired using this technology. Nevertheless, it is possible to try to recover them by taking advantage of the additional data provided by these systems: the calibrated video sequence of the acquisition, and the position of the projector light for each frame. In this paper, we propose a workflow that processes the video sequence with a photometric stereo approach, in order to refine the coarse geometry provided by the scanner. A normal map is first extracted by a method that accounts for the unevenly distributed sampling that generally results from the particular trajectory followed by this kind of scanners during the acquisition. This normal map is then integrated in order to recover missing geometric features. Good performances are achieved, since the whole workflow is particularly suited to GPU programming.Project(s): 3D-COFORM
Larue F, Dellepiane M, Scopigno R
High-speed scanning systems can be extremely valuable for Cultural Heritage applications, especially when large collections of small objects have to be acquired. However, fine details may not be acquired using this technology. Nevertheless, it is possible to try to recover them by taking advantage of the additional data provided by these systems: the calibrated video sequence of the acquisition, and the position of the projector light for each frame. In this paper, we propose a workflow that processes the video sequence with a photometric stereo approach, in order to refine the coarse geometry provided by the scanner. A normal map is first extracted by a method that accounts for the unevenly distributed sampling that generally results from the particular trajectory followed by this kind of scanners during the acquisition. This normal map is then integrated in order to recover missing geometric features. Good performances are achieved, since the whole workflow is particularly suited to GPU programming.Project(s): 3D-COFORM
2009
Conference article
Restricted
Image guided reconstruction of un-sampled data: a coherent filling for uncomplete cultural heritage models
Dellepiane M, Venturi A, Scopigno R
Nowadays, 3D scanning is widely applied to Cultural Heritage applications. In this peculiar context, the fact that the 3D models obtained from scanning are usually uncomplete can be an issue, especially because automatic hole filling techniques can create inaccurate surfaces. In this paper, we present a method to reconstruct unsampled portions of the 3D models by inferring information about the real shape of the missing part from an image. The needed data for surface creation are extracted from a predefined pattern which is projected on the real object, in the zone where the geometry of the 3D model is missing. The procedure, which is almost completely automatic, analyzes the image in order to extract the pattern and estimate the projector position. Then, the extracted information is used to obtain a hole filling which is coherent with the real shape of the object. A series of test on real objects proves that our method is able to recover geometrical features that cannot be reconstructed using state-of-the-art methods. Consequently, it can be used to obtain complete 3D models without creating false data.
Dellepiane M, Venturi A, Scopigno R
Nowadays, 3D scanning is widely applied to Cultural Heritage applications. In this peculiar context, the fact that the 3D models obtained from scanning are usually uncomplete can be an issue, especially because automatic hole filling techniques can create inaccurate surfaces. In this paper, we present a method to reconstruct unsampled portions of the 3D models by inferring information about the real shape of the missing part from an image. The needed data for surface creation are extracted from a predefined pattern which is projected on the real object, in the zone where the geometry of the 3D model is missing. The procedure, which is almost completely automatic, analyzes the image in order to extract the pattern and estimate the projector position. Then, the extracted information is used to obtain a hole filling which is coherent with the real shape of the object. A series of test on real objects proves that our method is able to recover geometrical features that cannot be reconstructed using state-of-the-art methods. Consequently, it can be used to obtain complete 3D models without creating false data.
See at:
CNR IRIS | CNR IRIS | vcg.isti.cnr.it
2010
Conference article
Open Access
Removing shadows for color projection using sun position estimation
Dellepiane M, Benedetti L, Scopigno R
The result of an outdoors 3D scanning acquisition campaign is usually an accurate 3D model of the site, but in most of the cases the quality of the color acquired by the scanner is not satisfying. Alternative solutions, like the projection of a photographic dataset acquired in a different stage, are still dependent on the quality of the initial images. The short time for the acquisition campaigns and the weather conditions often force the shooting of images taken under a strong direct sun illumination. This generates colored models of poor quality. In this paper we present a method to estimate the sun position starting from a geo-referenced 3D model and a set of images. The sun position can enhance both the image alignment and color projection phases. Moreover, the detection and removal of the shadows from the images produces a better and more coherent color in the final 3D model. Using this kind of approach, outdoor sites can be acquired producing a high quality color information together with an accurate geometric measurementProject(s): 3D-COFORM
Dellepiane M, Benedetti L, Scopigno R
The result of an outdoors 3D scanning acquisition campaign is usually an accurate 3D model of the site, but in most of the cases the quality of the color acquired by the scanner is not satisfying. Alternative solutions, like the projection of a photographic dataset acquired in a different stage, are still dependent on the quality of the initial images. The short time for the acquisition campaigns and the weather conditions often force the shooting of images taken under a strong direct sun illumination. This generates colored models of poor quality. In this paper we present a method to estimate the sun position starting from a geo-referenced 3D model and a set of images. The sun position can enhance both the image alignment and color projection phases. Moreover, the detection and removal of the shadows from the images produces a better and more coherent color in the final 3D model. Using this kind of approach, outdoor sites can be acquired producing a high quality color information together with an accurate geometric measurementProject(s): 3D-COFORM
See at:
diglib.eg.org | CNR IRIS | CNR IRIS
2010
Conference article
Restricted
Using Lego pieces for camera calibration: a preliminary study
Baronti L, Dellepiane M, Scopigno R
Camera calibration is an important operation for a number of applications in the field of Computer Graphics and Computer Vision. In particular, if the intrinsic parameters of the camera are known in advance, the accuracy of results is extremely improved. For this reason, several easy procedures to calibrate a camera have been proposed. The accuracy and ease-of-use of these procedures is strongly related to the needed calibration target, which is usually a single 2D printed pattern (i.e. a checkerboard). In this paper we propose the use of an alternative: a Lego structure. Lego pieces exhibit several strong-points, like the off-the-shelf availability and the geometric accuracy. Additionally, it's easy to prepare a structure and obtain the corresponding 3D model using freeware tools. Hence, we present the preliminary tests on the use of Lego structures for camera calibration. The tests have been performed on a user-friendly ad-hoc tool, which takes advantage of the peculiar features of Lego to automatically correct the positions of the 2D and 3D correspondences used for calibration. Results show that it's possible to obtain accurate results starting from a few photos, and that the entire procedure can be completed in a very short time.Source: EUROGRAPHICS TECHNICAL REPORT SERIES, pp. 97-100. Norrkoping, Sweden, 4-7 May 2010
Baronti L, Dellepiane M, Scopigno R
Camera calibration is an important operation for a number of applications in the field of Computer Graphics and Computer Vision. In particular, if the intrinsic parameters of the camera are known in advance, the accuracy of results is extremely improved. For this reason, several easy procedures to calibrate a camera have been proposed. The accuracy and ease-of-use of these procedures is strongly related to the needed calibration target, which is usually a single 2D printed pattern (i.e. a checkerboard). In this paper we propose the use of an alternative: a Lego structure. Lego pieces exhibit several strong-points, like the off-the-shelf availability and the geometric accuracy. Additionally, it's easy to prepare a structure and obtain the corresponding 3D model using freeware tools. Hence, we present the preliminary tests on the use of Lego structures for camera calibration. The tests have been performed on a user-friendly ad-hoc tool, which takes advantage of the peculiar features of Lego to automatically correct the positions of the 2D and 3D correspondences used for calibration. Results show that it's possible to obtain accurate results starting from a few photos, and that the entire procedure can be completed in a very short time.Source: EUROGRAPHICS TECHNICAL REPORT SERIES, pp. 97-100. Norrkoping, Sweden, 4-7 May 2010
See at:
diglib.eg.org | CNR IRIS | CNR IRIS
2011
Journal article
Restricted
Image guided reconstruction of un-sampled data: a filling technique for cultural heritage models
Dellepiane M, Venturi A, Scopigno R
Cultural Heritage (CH) is one of the major fields of application of 3D scanning technologies. In this context, one of the main limitations perceived by the practitioners is the uncompleteness of the sampling. Whenever we scan a complex artifact, the produced sampling usually presents a large number of unsampled regions. Many algorithmic solutions exist to close those gaps (from specific hole-filling algorithms to the drastic solution of using water-tight reconstruction methods). Unfortunately, adding patches over un-sampled regions is an issue in CH applications: if the 3D model should be used as a master document over the shape (and status) of the artwork, informed CH curators usually do not accept that an algorithm is used to {em guess} portions of a surface. In this paper, we present a low-cost setup and related algorithms to reconstruct un-sampled portions of the 3D models by inferring information about the real shape of the missing region from photographs. Data needed to drive the surface completion process are obtained by coupling a calibrated pattern of laser diodes to a digital camera. Thus, we are proposing a simple active acquisition device (based on consumer components and more flexible than standard 3D scanning devices) to improve selectively the sampling produced by a standard 3D scanning device. After acquiring one or more images with the laser-enhanced camera, an almost completely automatic process analyzes the image/s in order to extract the pattern, to estimate the laser projector intersections over the surface and determining coordinates of those points (using the consolidated triangulation approach). Then, the gathered geometric data are used to steer the hole filling in order to obtain a patch which is coherent with the real shape of the object. A series of tests on real objects proves that our method is able to recover geometrical features that cannot be reconstructed using state-of-the-art methods. Consequently, it can be used to obtain complete 3D models without creating plausible but false data.Source: INTERNATIONAL JOURNAL OF COMPUTER VISION, vol. 94 (issue 1), pp. 2-11
Project(s): 3D-COFORM
Dellepiane M, Venturi A, Scopigno R
Cultural Heritage (CH) is one of the major fields of application of 3D scanning technologies. In this context, one of the main limitations perceived by the practitioners is the uncompleteness of the sampling. Whenever we scan a complex artifact, the produced sampling usually presents a large number of unsampled regions. Many algorithmic solutions exist to close those gaps (from specific hole-filling algorithms to the drastic solution of using water-tight reconstruction methods). Unfortunately, adding patches over un-sampled regions is an issue in CH applications: if the 3D model should be used as a master document over the shape (and status) of the artwork, informed CH curators usually do not accept that an algorithm is used to {em guess} portions of a surface. In this paper, we present a low-cost setup and related algorithms to reconstruct un-sampled portions of the 3D models by inferring information about the real shape of the missing region from photographs. Data needed to drive the surface completion process are obtained by coupling a calibrated pattern of laser diodes to a digital camera. Thus, we are proposing a simple active acquisition device (based on consumer components and more flexible than standard 3D scanning devices) to improve selectively the sampling produced by a standard 3D scanning device. After acquiring one or more images with the laser-enhanced camera, an almost completely automatic process analyzes the image/s in order to extract the pattern, to estimate the laser projector intersections over the surface and determining coordinates of those points (using the consolidated triangulation approach). Then, the gathered geometric data are used to steer the hole filling in order to obtain a patch which is coherent with the real shape of the object. A series of tests on real objects proves that our method is able to recover geometrical features that cannot be reconstructed using state-of-the-art methods. Consequently, it can be used to obtain complete 3D models without creating plausible but false data.Source: INTERNATIONAL JOURNAL OF COMPUTER VISION, vol. 94 (issue 1), pp. 2-11
Project(s): 3D-COFORM
See at:
CNR IRIS | CNR IRIS | link.springer.com
2012
Contribution to book
Restricted
Automatic texturing without illumination artifacts from in-hand scanning data flow.
Larue F, Dellepiane M, Hamer H, Scopigno R
This paper shows how to improve the results of a 3D scanning system to allow to better fit the requirements of the Multi-Media and Cultural Heritage domains. A real-time in-hand scanning system is enhanced by further processing its intermediate data, with the goal of producing a digital 3D model with a high quality color texture and an improved representation of the high-frequency shape detail. The proposed solution starts from the usual output of the scanner, a 3D model and a video sequence gathered by the scanner sensor, for which the rigid motion is known at each frame. The produced color texture is deprived of the typical artifacts that generally appear while creating textures from several pictures: ghosting, shadows and specular highlights. In the case of objects made of diffuse materials, the system is also able to compute a normal map, thus improving the geometry acquired by the scanner. Results demonstrate that our texturing procedure is quite fast (a few minutes to process more than a thousand images). Moreover, the method is highly automatic, since only a few intuitive parameters must be tuned by the user, and all required computations are particularly suited to GPU programming, making the method convenient and scalable to graphics hardware.Source: COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE (PRINT), pp. 14-26
Project(s): 3D-COFORM
Larue F, Dellepiane M, Hamer H, Scopigno R
This paper shows how to improve the results of a 3D scanning system to allow to better fit the requirements of the Multi-Media and Cultural Heritage domains. A real-time in-hand scanning system is enhanced by further processing its intermediate data, with the goal of producing a digital 3D model with a high quality color texture and an improved representation of the high-frequency shape detail. The proposed solution starts from the usual output of the scanner, a 3D model and a video sequence gathered by the scanner sensor, for which the rigid motion is known at each frame. The produced color texture is deprived of the typical artifacts that generally appear while creating textures from several pictures: ghosting, shadows and specular highlights. In the case of objects made of diffuse materials, the system is also able to compute a normal map, thus improving the geometry acquired by the scanner. Results demonstrate that our texturing procedure is quite fast (a few minutes to process more than a thousand images). Moreover, the method is highly automatic, since only a few intuitive parameters must be tuned by the user, and all required computations are particularly suited to GPU programming, making the method convenient and scalable to graphics hardware.Source: COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE (PRINT), pp. 14-26
Project(s): 3D-COFORM
See at:
CNR IRIS | CNR IRIS | www.springerlink.com
2012
Conference article
Metadata Only Access
Teaching 3D acquisition for cultural heritage: a theory and practice approach.
Dellepiane M, Scopigno R
The paper presents the experience of a course (3D Graphics for Cultural Heritage) in the context of Humanistic Informatics degree. The goal of the course was to present an overview of the techniques for the acquisition of 3D models of real objects. The focus was put on freeware/open source solutions that could give the students the possibility to experiment directly on the data, and possibly apply them in their future activities. The acquisition techniques were divided in three groups: 3D scanning, Dense Stereo Reconstruction and Re-Lightable Images. Moreover, general concepts about 3D Graphics, remote visualization, and planning of projects were part of the subjects. The final project for each student consisted in a practical acquisition of a real objects, using one of the proposed techniques. The results of the projects showed that high quality 3D acquisition is now possible even with low-cost devices and freeware tools, and that it can be a strongpoint for the career of future young CH professionals.
Dellepiane M, Scopigno R
The paper presents the experience of a course (3D Graphics for Cultural Heritage) in the context of Humanistic Informatics degree. The goal of the course was to present an overview of the techniques for the acquisition of 3D models of real objects. The focus was put on freeware/open source solutions that could give the students the possibility to experiment directly on the data, and possibly apply them in their future activities. The acquisition techniques were divided in three groups: 3D scanning, Dense Stereo Reconstruction and Re-Lightable Images. Moreover, general concepts about 3D Graphics, remote visualization, and planning of projects were part of the subjects. The final project for each student consisted in a practical acquisition of a real objects, using one of the proposed techniques. The results of the projects showed that high quality 3D acquisition is now possible even with low-cost devices and freeware tools, and that it can be a strongpoint for the career of future young CH professionals.
See at:
diglib.eg.org | CNR IRIS
2013
Conference article
Open Access
Which infrastructure support for visual data creation, archiving and visualization?
Scopigno R, Dellepiane M
Visual data are nowadays a basic component of the massive data gathered in archaeology. With the term visual data we mean any visual representation that could be associated to an artwork, architecture or site, to describe its shape in terms of visual and geometric elements. Therefore, different representations are included: 2D images (standard images, panoramic images, Reflection Transformation Images - RTI), 2D graphical representations such as maps or drawings (usually represented by standard digital image files), 3D models (either sampled or reconstructed with modelling systems) or finally videos (grabbed from reality or computer animations). In the framework of the ARIADNE project, we are focusing on the services that an infrastructure for archaeological documentation should provide for managing these media. Our first goal is to present to users the capabilities of current technology (both commercial tools and resources produced in few recent EU projects) and to understand how to map the real needs of the user community on existing technologies and potential services for production, sharing and visualization. Training is an important component of an infrastructure project, due to the many media available and the complexity of both mastering data creation/presentation and of understanding which media fits better the specific documentation or visual analysis needs. Our purpose will be to help our community in building a clear view of the affordances of particular genres of representations, clarifying their documentation potential and the possible limitations wrt. storing, discovery, accessing, connecting with other data, and rendering. Designing an infrastructure requires also focusing on configuration and/or development (e.g. customization to user needs of open source solutions and of academic prototypes developed by EU projects). Obviously, visual data cannot be treated isolated from the other data. Integration should be designed to allow advanced visual data creation and visualization to inter-operate with standard databases and repositories.Project(s): ARIADNE
Scopigno R, Dellepiane M
Visual data are nowadays a basic component of the massive data gathered in archaeology. With the term visual data we mean any visual representation that could be associated to an artwork, architecture or site, to describe its shape in terms of visual and geometric elements. Therefore, different representations are included: 2D images (standard images, panoramic images, Reflection Transformation Images - RTI), 2D graphical representations such as maps or drawings (usually represented by standard digital image files), 3D models (either sampled or reconstructed with modelling systems) or finally videos (grabbed from reality or computer animations). In the framework of the ARIADNE project, we are focusing on the services that an infrastructure for archaeological documentation should provide for managing these media. Our first goal is to present to users the capabilities of current technology (both commercial tools and resources produced in few recent EU projects) and to understand how to map the real needs of the user community on existing technologies and potential services for production, sharing and visualization. Training is an important component of an infrastructure project, due to the many media available and the complexity of both mastering data creation/presentation and of understanding which media fits better the specific documentation or visual analysis needs. Our purpose will be to help our community in building a clear view of the affordances of particular genres of representations, clarifying their documentation potential and the possible limitations wrt. storing, discovery, accessing, connecting with other data, and rendering. Designing an infrastructure requires also focusing on configuration and/or development (e.g. customization to user needs of open source solutions and of academic prototypes developed by EU projects). Obviously, visual data cannot be treated isolated from the other data. Integration should be designed to allow advanced visual data creation and visualization to inter-operate with standard databases and repositories.Project(s): ARIADNE
2013
Conference article
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Edge detection on polynomial texture maps
Brognara C, Corsini M, Dellepiane M, Giachetti A
In this paper we propose a simple method to extract edges from Polynomial Texture Maps (PTM) or other kinds of Reflection Transformation Image (RTI) files. It is based on the idea of following 2D lines where the variation of corresponding 3D normals computed from the PTM coefficients is maximal. Normals are estimated using a photometric stereo approach, derivatives along image axes directions are computed in a multiscale framework providing normal discontinuity and orientation maps and lines are finally extracted using non-maxima suppression and hysteresis thresholds as in Canny's algorithm. In this way it is possible to discover automatically potential structure of interest (inscriptions, small reliefs) on Cultural Heritage artifacts of interest without the necessity of interactively recreating images using different light directions. Experimental results obtained on test data and new PTMs acquired in an archaeological site in the Holy Land with a simple low-end camera, show that the method provides potentially useful results.
Brognara C, Corsini M, Dellepiane M, Giachetti A
In this paper we propose a simple method to extract edges from Polynomial Texture Maps (PTM) or other kinds of Reflection Transformation Image (RTI) files. It is based on the idea of following 2D lines where the variation of corresponding 3D normals computed from the PTM coefficients is maximal. Normals are estimated using a photometric stereo approach, derivatives along image axes directions are computed in a multiscale framework providing normal discontinuity and orientation maps and lines are finally extracted using non-maxima suppression and hysteresis thresholds as in Canny's algorithm. In this way it is possible to discover automatically potential structure of interest (inscriptions, small reliefs) on Cultural Heritage artifacts of interest without the necessity of interactively recreating images using different light directions. Experimental results obtained on test data and new PTMs acquired in an archaeological site in the Holy Land with a simple low-end camera, show that the method provides potentially useful results.
See at:
CNR IRIS | CNR IRIS | CNR IRIS | link.springer.com
2013
Conference article
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Digital reconstruction and visualization in archaeology. Case-study drawn from the work of the Swedish Pompeii Project
Dell'Unto N, Ferdani D, Leander A, Dellepiane M, Callieri M, Lindgren S
The Swedish Pompeii Project started in 2000 as a research and fieldwork activity initiated by the Swedish Institute in Rome. The aim was to record and analyze an entire Pompeian city-block, Insula V 1. Since autumn 2011 a new branch of advanced digital archaeology, involving 3D reconstructions and documentation methods, was added to the project agenda. The insula was completely digitized using laser scanner technology and the raw data were employed to develop different research activities in the area of digital visualization. This paper presents the recent results of the 3D interpretation of the house of Caecilius Iucundus. This research activity was developed employing a large variety of historical and archaeological sources such as: archaeological reports, historical image documentation (printed as well as in edited material) and analysis of the in situ structures. This work was characterized by the experimentation of a new workflow of data development, where the elaboration of the interpreted structures took place directly in virtual space, using the scanned model as geometrical reference. This method easily connected all the historical and archaeological sources collected for the interpretation, opening a new discussion about different possible interpretation of the house. Moreover, a Cave Automatic Virtual Environment (CAVE) was used in different occasions as platform where the different hypotheses could be discussed in the context given by the actual state of the archaeological structures. The use of an accurate and resolute replica of the site as a backdrop for the virtual reconstruction allowed a high level of control on the proposed hypotheses during the interpretation process. This study enabled the acquisition of new and important information about the house, thus, bringing a significant contribution to the archaeological analysis of Insula V 1, suggested as pilot project for wider use.
Dell'Unto N, Ferdani D, Leander A, Dellepiane M, Callieri M, Lindgren S
The Swedish Pompeii Project started in 2000 as a research and fieldwork activity initiated by the Swedish Institute in Rome. The aim was to record and analyze an entire Pompeian city-block, Insula V 1. Since autumn 2011 a new branch of advanced digital archaeology, involving 3D reconstructions and documentation methods, was added to the project agenda. The insula was completely digitized using laser scanner technology and the raw data were employed to develop different research activities in the area of digital visualization. This paper presents the recent results of the 3D interpretation of the house of Caecilius Iucundus. This research activity was developed employing a large variety of historical and archaeological sources such as: archaeological reports, historical image documentation (printed as well as in edited material) and analysis of the in situ structures. This work was characterized by the experimentation of a new workflow of data development, where the elaboration of the interpreted structures took place directly in virtual space, using the scanned model as geometrical reference. This method easily connected all the historical and archaeological sources collected for the interpretation, opening a new discussion about different possible interpretation of the house. Moreover, a Cave Automatic Virtual Environment (CAVE) was used in different occasions as platform where the different hypotheses could be discussed in the context given by the actual state of the archaeological structures. The use of an accurate and resolute replica of the site as a backdrop for the virtual reconstruction allowed a high level of control on the proposed hypotheses during the interpretation process. This study enabled the acquisition of new and important information about the house, thus, bringing a significant contribution to the archaeological analysis of Insula V 1, suggested as pilot project for wider use.
See at:
CNR IRIS | CNR IRIS | www.digitalheritage2013.org
2013
Conference article
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Global refinement of image-to-geometry registration for color projection
Dellepiane M, Scopigno R
The management, processing and visualization of color information is a critical subject in the context of the acquisition and visualization of real objects. Especially in the context of Cultural Heritage, artifacts are so complex or hard to handle that the appearance information has to be extracted from a set of images. The images usually have to be registered to the 3D model of the objects, in order to transfer the needed information. Hence, the problem of image-to-geometry registration has been thoroughly studied by the Computer Graphics and Computer Vision community. Several methods have been proposed, but a fully automatic and generic solution is still missing. Moreover, small misalignments often lead to visible artifacts in the final colored 3D models. In this paper, we propose a method to refine the alignment of a group of images which has been already registered to a 3D model. Taking advantage of the overlapping among the images, and applying a statistical global method based on Mutual Information, the registration error is distributed among all the elements of the dataset. Hence, the quality of color projection is improved, especially when dealing with small details. The method was tested on a number of heterogeneous Cultural Heritage objects, bringing to a visible improvement in the rendering quality. The method is fully automatic, and it does not need powerful hardware or long processing time. Hence, it represents a valid solution for a wide application on CH artifacts.Project(s): HARVEST4D
Dellepiane M, Scopigno R
The management, processing and visualization of color information is a critical subject in the context of the acquisition and visualization of real objects. Especially in the context of Cultural Heritage, artifacts are so complex or hard to handle that the appearance information has to be extracted from a set of images. The images usually have to be registered to the 3D model of the objects, in order to transfer the needed information. Hence, the problem of image-to-geometry registration has been thoroughly studied by the Computer Graphics and Computer Vision community. Several methods have been proposed, but a fully automatic and generic solution is still missing. Moreover, small misalignments often lead to visible artifacts in the final colored 3D models. In this paper, we propose a method to refine the alignment of a group of images which has been already registered to a 3D model. Taking advantage of the overlapping among the images, and applying a statistical global method based on Mutual Information, the registration error is distributed among all the elements of the dataset. Hence, the quality of color projection is improved, especially when dealing with small details. The method was tested on a number of heterogeneous Cultural Heritage objects, bringing to a visible improvement in the rendering quality. The method is fully automatic, and it does not need powerful hardware or long processing time. Hence, it represents a valid solution for a wide application on CH artifacts.Project(s): HARVEST4D
See at:
CNR IRIS | CNR IRIS | www.digitalheritage2013.org