A Full Scale Camera Calibration Technique with Automatic Model Selection – Extension and Validation

This thesis presents work on the testing and development of a complete camera calibration approach which can be applied to a wide range of cameras equipped with normal, wide-angle, fish-eye, or telephoto lenses. The full scale calibration approach estimates all of the intrinsic and extrinsic parameters. The calibration procedure is simple and does not require prior knowledge of any parameters. The method uses a simple planar calibration pattern. Closed-form estimates for the intrinsic and extrinsic parameters are computed followed by nonlinear optimization. Polynomial functions are used to describe the lens projection instead of the commonly used radial model. Statistical information criteria are used to automatically determine the complexity of the lens distortion model. In the first stage experiments were performed to verify and compare the performance of the calibration method. Experiments were performed on a wide range of lenses. Synthetic data was used to simulate real data and validate the performance. Synthetic data was also used to validate the performance of the distortion model selection which uses Information Theoretic Criterion (AIC) to automatically select the complexity of the distortion model. In the second stage work was done to develop an improved calibration procedure which addresses shortcomings of previously developed method. Experiments on the previous method revealed that the estimation of the principal point during calibration was erroneous for lenses with a large focal length. To address this issue the calibration method was modified to include additional methods to accurately estimate the principal point in the initial stages of the calibration procedure. The modified procedure can now be used to calibrate a wide spectrum of imaging systems including telephoto and verifocal lenses. Survey of current work revealed a vast amount of research concentrating on calibrating only the distortion of the camera. In these methods researchers propose methods to calibrate only the distortion parameters and suggest using other popular methods to find the remaining camera parameters. Using this proposed methodology we apply distortion calibration to our methods to separate the estimation of distortion parameters. We show and compare the results with the original method on a wide range of imaging systems

From ”Sapienza” to “Sapienza, State Archives in Rome”. A looping effect bringing back to the original source communication and culture by innovative and low cost 3D surveying, imaging systems and GIS applications

Applicazione di tecnologie mensorie integrate Low Cost,web GIS,applicazione di tecniche di Computational photography per la comunicazione e condivisione dei dati, sistemi di Cloud computing.Archiviazione Grandi DatiHigh Quality survey models, realized by multiple Low Cost methods and technologies, as a container to sharing Cultural and Archival Heritage, this is the aim guiding our research, here described in its primary applications. The SAPIENZA building, a XVI century masterpiece that represented the first unified headquarters of University in Rome, plays since year 1936, when the University moved to its newly edified campus, the role of the main venue for the State Archives. By the collaboration of a group of students of the Architecture Faculty, some integrated survey methods were applied on the monument with success. The beginning was the topographic survey, creating a reference on ground and along the monument for the upcoming applications, a GNNS RTK survey followed georeferencing points on the internal courtyard. Dense stereo matching photogrammetry is nowadays an accepted method for generating 3D survey models, accurate and scalable; it often substitutes 3D laser scanning for its low cost, so that it became our choice. Some 360°shots were planned for creating panoramic views of the double portico from the courtyard, plus additional single shots of some lateral spans and of pillars facing the court, as a single operation with a double finality: to create linked panotours with hotspots to web-linked databases, and 3D textured and georeferenced surface models, allowing to study the harmonic proportions of the classical architectural order. The use of free web Gis platforms, to load the work in Google Earth and the realization of low cost 3D prototypes of some representative parts, has been even performed

Robotic Micromanipulation and Microassembly using Mono-view and Multi-scale visual servoing.

International audienceThis paper investigates sequential robotic micromanipulation and microassembly in order to build 3-D microsystems and devices. A mono-view and multiple scale 2-D visual control scheme is implemented for that purpose. The imaging system used is a photon video microscope endowed with an active zoom enabling to work at multiple scales. It is modelled by a non-linear projective method where the relation between the focal length and the zoom factor is explicitly established. A distributed robotic system (xy system, z system) with a twofingers gripping system is used in conjunction with the imaging system. The results of experiments demonstrate the relevance of the proposed approaches. The tasks were performed with the following accuracy: 1.4 m for the positioning error, and 0.5 for the orientation error

Positioning in time and space: cost-effective exterior orientation for airborne archaeological photographs

Since manned, airborne aerial reconnaissance for archaeological purposes is often characterised by more-or-less random photographing of archaeological features on the Earth, the exact position and orientation of the camera during image acquisition becomes very important in an effective inventorying and interpretation workflow of these aerial photographs. Although the positioning is generally achieved by simultaneously logging the flight path or directly recording the camera's position with a GNSS receiver, this approach does not allow to record the necessary roll, pitch and yaw angles of the camera. The latter are essential elements for the complete exterior orientation of the camera, which allows – together with the inner orientation of the camera – to accurately define the portion of the Earth recorded in the photograph. This paper proposes a cost-effective, accurate and precise GNSS/IMU solution (image position: 2.5 m and orientation: 2°, both at 1σ) to record all essential exterior orientation parameters for the direct georeferencing of the images. After the introduction of the utilised hardware, this paper presents the developed software that allows recording and estimating these parameters. Furthermore, this direct georeferencing information can be embedded into the image's metadata. Subsequently, the first results of the estimation of the mounting calibration (i.e. the misalignment between the camera and GNSS/IMU coordinate frame) are provided. Furthermore, a comparison with a dedicated commercial photographic GNSS/IMU solution will prove the superiority of the introduced solution. Finally, an outlook on future tests and improvements finalises this article

Integration of photogrammetric and terrestrial laser scanning techniques for heritage documentation

[EN] This paper presents the preliminary works of the Integration of Photogrammetric and Terrestrial Laser Scanner Techniques for Heritage Documentation Research Project (IFOTEL TIN2009-09939; Ministry of Science and Innovation, National Programme R+D+I, 2008-2011). The IFOTEL project aims with the improvement and optimization of heritage documentation by means of combination and integration of different methods and techniques, mainly close range photogrammetry (both terrestrial and aerial with light platforms), terrestrial laser scanner and surveying, joining the advantages of the different methods but also minimizing the disadvantages of each single technique.[ES] Este trabajo presenta las ideas y trabajos preliminares del proyecto Integración de Técnicas de Fotogrametría y Escáner Láser Terrestre para la Documentación Patrimonial (IFOTEL TIN2009-09939; Ministerio de Ciencia e Innovación, Plan Nacional I+D+i, 2008-2011), con el que se pretende buscar la mejora y optimización de la documentación del patrimonio cultural mediante la combinación de diferentes métodos, especialmente de fotogrametría (tanto terrestre como aérea mediante el uso de plataformas ligeras), técnicas de barrido láser (LÍDAR terrestre) y topografía, que aúnen las ventajas de todos ellos minimizando sus inconvenientes.The present study has been financed by grant TIN2009-09939 (IFOTEL Project) from the Ministry of Science and Innovation, National Programme R+D+I, 2008-2011, European Regional Development Funds (FEDER) and TEP-213 Research Group (PAI, Junta de Andalucía).Cardenal Escarcena, FJ.; Mata De Castro, E.; Pérez García, JL.; Mozas Calvache, AT.; Fernández Del Castillo, T.; Delgado García, J.; Ureña Cámara, M.... (2011). Integration of photogrammetric and terrestrial laser scanning techniques for heritage documentation. Virtual Archaeology Review. 2(3):53-57. https://doi.org/10.4995/var.2011.4605535723CIPA (2010). CIPA_Heritage Documentation: Objectives and Activities. In: http://cipa.icomos.org/index.php?id=40 (last accessed April 2010).EVARAERTS, J. (2008). Unmanned aerial vehicles for photogrammetry and remote sensing. In:Advances in Photogrammtery, Remote Sensing and Spatial Information sciences:2008 ISPRS Congress Book. Eds. Li, Chen y Baltsavias. Chapter 9, 117-126. CRC Press, Taylor and Francis Gr. London. http://dx.doi.org/10.1201/9780203888445.ch9HABIB, A. (2009). Integration of LIDAR and Photogrammetric Data: Triangulation and Orthorectification. In: Topographic Laser Ranging and Scanning. Principles and Processing. Eds.: Shan & Toth. Chap. 13, 371-402, CRC Press, Taylor and Francis Gr. London.MOZAS, A., PEREZ-GARCIA, J.L., BARBA, V., LOPEZ-ARENAS, A. (this congress). Estudio geométrico de piezas arqueológicas a partir de un modelo virtual 3D. II International Meeting on Graphic Archaeology and Informatics, Cultural Heritage and Innovation. Arqueologica 2.0. Sevilla, June 16-19 2010.PATIAS, P. GRUSSENMEYER, P., HANKE, K. (2008). Applications in Cultural Heritage Documentation. In:Advances in Photogrammtery, Remote Sensing and Spatial Information sciences:2008 ISPRS Congress Book. Eds. Li, Chen y Baltsavias. Chapter. 27, 363-383. CRC Press, Taylor and Francis Gr. London.PEREZ-GARCIA, J.L., MOZAS, A., CARDENAL, J. (this congress). Fotogrametría de bajo coste para la modelización de edificios históricos. II International Meeting on Graphic Archaeology and Informatics, Cultural Heritage and Innovation. Arqueologica 2.0. Sevilla, Jun