Novel data registration techniques for art diagnostics and 3D heritage visualization

In the last decade, 3D active sensors, like laser scanners or structured light systems, have been used for both documentation and analysis of historical and archaeological finds. Although remarkable results have been obtained, the high cost of the 3D sensors and of the processing software required has been a limiting factor for an extensive application of these technologies to the Cultural Heritage field. Recently, however, a very low-cost 3D scanning device has been introduced to the market, with nominal performances comparable with those of far more expensive systems. The objective of this contribution is the evaluation and characterization of such type of sensor, by means of a set of comparative tests with two other widely diffused laser scanners. The tests are focused on their instrumental performances, in terms of precision and accuracy, as well as on actual results on a few small archeological finds

Restoration of Aged Photos by Color Transplant

Starting from XVIII century, images have been used to testify the historical memories of the society. Among others, they are used for the representation of ancient documents, art objects, and similar. Even if the photographic technique has got several improvements since its origin, photos are still liable for several damages, both concerning the physical support and the colors and figures which are depicted in it: scratches or rips are examples of common physical injuries, while the fading or red (or yellow) toning of its colors are representative of “chemical” damages. In this paper, a novel method able to infer the original beauty of digital reproductions of aged photos is presented. It is based on the comparison between the degraded image and a not-degraded one, showing similar contents; that is, it is possible to transplant the colors coming from the not-degraded image in the degraded one. Similarly, the method can be also applied to digital reproductions of faded goods. The key point is a dualism between analytical mechanics and color theory; that is, the scatter plot diagrams of x and y normalized coordinates of the colors of both the images are computed, and each of them are accounted as a system of point masses, thus provided of an inertia ellipsoid and inertia axes. To perform the color correction of the degraded image, the inertia ellipsoid of it is moved up to overlap the not-degraded one, thus performing a transplant of colors

Restoration of aged photos by color transplant

Starting from XVIII century, images have been used to testify the historical memories of the society. Among others, they are used for the representation of ancient documents, art objects, and similar. Even if the photographic technique has got several improvements since its origin, photos are still liable for several damages, both concerning the physical support and the colors and figures which are depicted in it: scratches or rips are examples of common physical injuries, while the fading or red (or yellow) toning of its colors are representative of \u201cchemical\u201d damages. In this paper, a novel method able to infer the original beauty of digital reproductions of aged photos is presented. It is based on the comparison between the degraded image and a not-degraded one, showing similar contents; that is, it is possible to transplant the colors coming from the not-degraded image in the degraded one. Similarly, the method can be also applied to digital reproductions of faded goods. The key point is a dualism between analytical mechanics and color theory; that is, the scatter plot diagrams of x and y normalized coordinates of the colors of both the images are computed, and each of them are accounted as a system of point masses, thus provided of an inertia ellipsoid and inertia axes. To perform the color correction of the degraded image, the inertia ellipsoid of it is moved up to overlap the not-degraded one, thus performing a transplant of colors

Automated multispectral texture mapping of 3D models

Recently, thanks to the diffusion of scanning devices and the availability of powerful 3D modelling software, as well as to the improvements in the automation of the image-based modelling approach, 3D models are more and more considered in several research fields, such as inspection, navigation, object identification, visualisation and animation, and recently also in Cultural Heritage. Documentation in case of loss or damage, virtual tourism and museum, education resources, interaction (without risk of damage), and so forth are only few examples of applications where they has become a fundamental step. However, 3D models obtained with these technologies are often lacking a suitable photorealistic appearance, due to low quality acquired texture, or to the complete absence of it. Moreover, it is often of specific interest to texture with images different from photos, like multispetral/multimodal images (IR, Xrays, UV fluorescence). In such cases, a postprocessing texture mapping is needed, and it is often achieved through manual alignment of the model and the related texture. In this work, we propose a fully automatic approach for multispectral texture mapping. The method relies on the extraction from the model geometry of a depth map, in form of an image, whose pixels maintain an exact correspondence with vertices of the 3D model; the subsequent step is registratio , between such image and the chosen texture, with a very robust registration algorithm, based on Maximixation of Mutual Information. The results presented show the effectiveness of the proposed method

Automated multispectral texture mapping of 3D models

Recently, thanks to the diffusion of scanning devices and the availability of powerful 3D modelling software, as well as to the improvements in the automation of the image-based modelling approach, 3D models are more and more considered in several research fields, such as inspection, navigation, object identification, visualisation and animation, and recently also in Cultural Heritage. Documentation in case of loss or damage, virtual tourism and museum, education resources, interaction (without risk of damage), and so forth are only few examples of applications where they has become a fundamental step. However, 3D models obtained with these technologies are often lacking a suitable photorealistic appearance, due to low quality acquired texture, or to the complete absence of it. Moreover, it is often of specific interest to texture with images different from photos, like multispetral/multimodal images (IR, Xrays, UV fluorescence). In such cases, a postprocessing texture mapping is needed, and it is often achieved through manual alignment of the model and the related texture. In this work, we propose a fully automatic approach for multispectral texture mapping. The method relies on the extraction from the model geometry of a depth map, in form of an image, whose pixels maintain an exact correspondence with vertices of the 3D model; the subsequent step is registratio , between such image and the chosen texture, with a very robust registration algorithm, based on Maximixation of Mutual Information. The results presented show the effectiveness of the proposed method

Performances evaluation of a low cost active sensor for Cultural Heritage documentation

In the last decade, 3D active sensors, like laser scanners or structured light systems, have been used for both documentation and analysis of historical and archaeological finds. Although remarkable results have been obtained, the high cost of the 3D sensors and of the processing software required has been a limiting factor for an extensive application of these technologies to the Cultural Heritage field. Recently, however, a very low-cost 3D scanning device has been introduced to the market, with nominal performances comparable with those of far more expensive systems. The objective of this contribution is the evaluation and characterization of such type of sensor, by means of a set of comparative tests with two other widely diffused laser scanners. The tests are focused on their instrumental performances, in terms of precision and accuracy, as well as on actual results on a few small archeological finds