Towards a demonstrator for autonomous object detection on board Gaia Shan Mignot To cite this version: Shan Mignot. Towards a demonstrator for autonomous object detection on board Gaia. Signal and Image processing. Observatoire de Paris, 2008. English. tel-00340279v2 HAL Id: tel-00340279 https://tel.archives-ouvertes.fr/tel-00340279v2 Submitted on 21 Nov 2008 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. OBSERVATOIRE DE PARIS ECOLE´ DOCTORALE ASTRONOMIE ET ASTROPHYSIQUE D'^ILE-DE-FRANCE Thesis ASTRONOMY AND ASTROPHYSICS Instrumentation Shan Mignot Towards a demonstrator for autonomous object detection on board Gaia (Vers un demonstrateur pour la d´etection autonome des objets `abord de Gaia) Thesis directed by Jean Lacroix then Albert Bijaoui Presented on January 10th 2008 to a jury composed of: Ana G´omez GEPI´ - Observatoire de Paris President Bertrand Granado ETIS - ENSEA Reviewer Michael Perryman ESTEC - Agence Spatiale Europ´eenne Reviewer Daniel Gaff´e LEAT - Universit´ede Nice Sophia-Antipolis Examiner Michel Paindavoine LE2I - Universit´ede Bourgogne Examiner Albert Bijaoui Cassiop´ee- Observatoire de la C^ote d'Azur Director Gregory Flandin EADS Astrium SAS Guest Jean Lacroix LPMA - Universit´eParis 6 Guest Gilles Moury Centre National d'Etudes´ Spatiales Guest Acknowledgements The journey to the stars is a long one. If the poet may with one swift movement of his imagination sweep the reader off his feet to embark at their summons on a voyage to the blinking stars, for the multitude, the path remains undecipherable. Many an intriguing stratagems have been devised by generations of men yearning for such freedom and, alas, of those who have succeeded little remains but awe for their genius or for their folly. By no means do we hope to compare with them. Instead, with the sand at our feet to the stars above our heads, we venture to construct a ladder, grain per grain, and with infinite patience and method, eventually, step by step. May the readers forgive the means, overlook the ticking of the inflexible clock and bear with us long enough to either discard our laborious undertaking with evidence or to contribute their own grain. for such an endeavour cannot be a solitary one. And, indeed, a solitary one it has not been. From the start, the buzz of the contradictors and of the collaborators was heard surrounding our molehill. Certainly, the improbable balance in which it now stands owes much to the varied views of the scientists, of the engineers, of the agencies as of industry. Pray, accept our gratitude for doubts, good counsels, militant beliefs, patient contributions, precise criticisms have shaped the edifice, sometimes like a wind bringing down feverish protrusions, sometimes like a lever. Of all, special praise must be given to my directors and my proofreaders, and among them to Philippe Laporte who has not only groped for viable solutions in the realm of hardware in our company, but has also bravely ventured in inspecting every single portion of this text where many dangers lay in hidding. Family, friends and our sweetheart have also played a decisive role. Some with earthly, and others with not so earthly means. Let them not be forgotten, for if we have come within reach of the stars it is certainly because they have made us stand as on the shoulders of giants. ii Contents Foreword xiii I Introduction 1 1 The Gaia mission 3 1.1 Introduction . 3 1.2 Scientificreturn................................................. 5 1.3 Thesatellite................................................... 7 1.3.1 Measurement principle . 7 1.3.2 Overview of operation . 9 1.3.3 CCD technology . 13 1.4 Conclusion . 17 2 On-board processing 19 2.1 Introduction . 19 2.2 Functional needs . 20 2.2.1 Processing flow . 20 2.2.2 Specifications . 21 2.2.3 Processing capabilities . 26 2.3 Constraints . 26 2.3.1 Space . 26 2.3.2 Radiations . 27 2.4 Quality assurance . 28 2.4.1 Component policy . 28 2.4.2 Availability . 29 2.4.3 Qualification . 29 2.5 Architecture . 30 2.5.1 Paradigms . 30 2.5.2 PDHS.................................................. 30 2.6 Conclusion . 31 II Algorithms 33 3 Algorithmic framework 35 3.1 Introduction . 35 3.1.1 A bit of history. 35 3.1.2 Models ................................................. 36 3.2 Image model . 37 3.2.1 Acquisition . 37 3.2.2 Simulation . 39 3.3 Needs ...................................................... 40 3.4 Approaches . 43 3.4.1 Transforms . 43 3.4.2 Local analysis . 44 3.4.3 Segmentation . 44 3.5 Processing flow . 45 iv CONTENTS 3.5.1 Software & hardware partition . 45 3.5.2 Overview . 46 3.6 Conclusion . 49 4 Pre-calibration 53 4.1 Introduction . 53 4.2 Motivation . 54 4.2.1 Effects . 54 4.2.2 Policy.................................................. 54 4.3 Algorithms . 55 4.3.1 Linear transform . 55 4.3.2 Dead samples . 57 4.4 Architecture . 59 4.4.1 Processing flow . 59 4.4.2 Sample replacement . 60 4.5 Conclusion . 60 5 Background estimation 61 5.1 Introduction . 61 5.1.1 Need . 61 5.1.2 Contributors . 62 5.2 Background statistic . 63 5.2.1 Regional background . 63 5.2.2 Estimator . 64 5.2.3 Replacement strategy . 66 5.2.4 Background map . 68 5.3 Performances . 69 5.3.1 Precision . 70 5.3.2 Robustness . 70 5.3.3 Representativity . 71 5.4 Algorithms . 72 5.4.1 Histograms . 72 5.4.2 Mode determination . 73 5.4.3 Interpolation . ..