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| GEOG0234-1 | Photogrammetry
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| Duration : | 30h Th, 15h Pr |
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| Number of credits : |
| Master in Geographical Sciences, general orientation, in-depth approach, 1st year | | 5 |
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| Master in Geographical Sciences, general orientation, didactic approach, 1st year | | 5 |
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| Master en sciences géographiques, orientation générale, à finalité spécialisée en développement territorial et géomatique, 1st year | | 5 |
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| Master in Geographical Sciences, general orientation, specialized approach, 1st year | | 5 |
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| Master en sciences géographiques, orientation géomatique et géométrologie, à finalité spécialisée, 1st year | | 5 |
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| Master en sciences géographiques, orientation générale, à finalité spécialisée en géomorphologie, 1st year | | 5 |
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| Lecturer : | Yves Cornet |
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Language(s) of instruction :
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| French language |
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Organisation and examination :
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| Teaching in the first semester, examination in June |
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Course contents :
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| Theory
I. Introduction (historical reminder, definition, aim)
II. Exploitation of one photograph
1. Characteristics of an aerial photograph
2. Geometric concepts of the central projection
3. Frame of reference
4. Perspective rays bundle
5. Fundamental relationship of geometric optics
6. Distant object (p'=f)
7. Scale of the photograph
III. Exploitation of two photographs (stereoscopic couple)
1. Stereo-photgrammetry, frames of reference, common covering zone, base, homologous points
2. Some survey reminders (direct or indirect survey or short base) and the links with photogrammetry
IV. Photographic rectification
V. Principles of aerial stereo-photogrammetry
VI. Fundamental formula of the parallax
VII. Exploitation of the transversal parallax formula
VIII. Distortions of a stereo-photogrammetric model
IX. Internal orientation
X. Relative analogical empirical orientation
XI. Absolute orientation
XII. Analytical photogrammetry
XIII. Creation of epipolar documents, automation of the search for homologous points and MNS and ortho-images production
XIV. Accuracy of stereophotogrammetry
XV. Preparation of a mission
Practical work
Practical work is carried out under controlled autonomy.
A stereo couple of scanned photographs, known 2D coordinate points and the certificate of calibration of the chamber are supplied to students.
They also have a series of practicables programmed in VBA and DDPS software developed in our unit.
They are required to use the two software programs to carry out the different stages of the photogrammetric procedure. They must also reproduce some objects in 3D and validate the results. A comparison of the precision resulting from this validation with the expected accuracy based on the geometric characteristics of flight and acquisitions on one hand and the calibration certificate on the other must also be carried out. The students will then have to write a report. |
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Learning outcomes of the course :
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| The student will be able to
* Understand the geometric model for acquiring aerial photographs (perspective model-central projection).
* Understand the interest of calibrating the chamber and the application of the calibration model during the later orientation.
* Understand the formation of the 3D model obtained by relative orientation (collinearity, coplanarity, scale condition).
* Understand the geometric transformations of absolute orientation from 3D coordinates resulting from internal and relative orientations.
* Understand the geometric transformations of calculating epipolar coordinates from 3D coordinates resulting from internal and relative orientations.
* Understand the interest of changing to epipolar coordinates (automated search for homologous points) and the calculation procedure for MNS and ortho-images (only under DDPS).
* Become aware of the problem of precision and its a priori and a posteriori estimation.
* With the exception of aerotriangulation involving more than one couple, all the procedures studied should enable students to manage an operational photogrammetric project, in the professional environment, with the necessary rigour and thanks to a perfect understanding of the techniques by adopting professional software solutions that are generally available in this area.
A future evolution of the course is envisaged. It will consist of the integration of a chapter on aerotriangulation in the theory course and practical exercises. The programming of the different stages (Matlab, Octave or Python) and the use of free software during practical work (MicMac developed by 'ENSG) also constitute a foreseeable evolution. Given the limited number of hours in this course of the first masters, these problems could nonetheless be the subject of the course GEOG0271-A-a of "Special questions on the acquisition of spatial data" delivered in the 2nd year of the Masters. |
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Prerequisites and co-requisites/ Recommended optional programme components :
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| The course uses notions of geometry and matrix calculus from the mathematics course. Notions of geometrcal optics from the physics course and least squares adjustment from the numerical computation, statistics and error theory courses constitute another prerequisite. In addition, several notions from the remote sensing course are also used.
Finally, the way of thinking and analytical rigour developed during scientific courses of the three years of the Baccalaureat and secondary studies also constitute an advantage for those taking this photogrammetry course and who wish to reach the required performance level in the professional world. |
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Planned learning activities and teaching methods :
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| The theory course is of the ex-cathedra type. Many complementary reminders to the digital support material made available to students will be written on the blackboard. At the beginning of each session, a period of fifteen minutes is planned so that the students can ask questions about the material seen during the previous session.
The practical work which begins after the theory course is supervised and carried out autonomously. The emphasis is placed on the technical manipulation aspect of the two software tools made available to the students by establishing a strong link with the theoretical concepts. The complete photogrammetric procedure must be executed with the help of the two software programs. At the end of the practical work, the students must write a report describing the technical procedures and demonstrating the procedure and demonstrating a good understanding of the significance of inputs and outputs for each stage. The specificities of the technical solutions suggested by each software programme must also be listed and explained.
It is also important to mention that the students can install the software programs developed in our unit on their PCs and used during practical sessions (Executables VBA and DDPS - Didactical Digital Photogrammetric Software). These software programs are available on eCampus and the explanatory manuals for calculation methods and use are also available.
In order to analyse the reference data (spot heights), students are recommended to use the software program Quantum GIS. In order to select homologous points on the images, they can use the software program Idrisi. The user license for this software program is available through the VPN of ULg. If they wish, they can freely choose another working environment than that of the practical work sessions. To obtain information on access to Idrisi and other software programs, they can consult the following web address: http://www.gitan.ulg.ac.be/cms. If they wish to have access to computerized rooms B5a/4/18 et B5a/2/35 to work on or develop their practical project work, they can contact the staff of the Geomatics Unit. |
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Mode of delivery (face-to-face ; distance-learning) :
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| The teaching will be face-to-face.
The theory classes will be ex cathedra and autonomous and supervised practical work will take place on Thursday afternoons in the room B5a/2/35 or B5a/4/18. Presence at the practical work sessions is obligatory. |
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Recommended or required readings :
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| Karl Kraus, Peter Waldhäusl, 1998. Manual of photogrammetry. Principles and fundamental procedures. Hermès - Lavoisier, 406p. http://www.eyrolles.com/Sciences/Livre/manuel-de-photogrammetrie-9782866016562. |
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Assessment methods and criteria :
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| Assessment is carried out orally. The questions asked of the student are inspired by imprecisions observed on reading the practical work report. The number of questions is a function of the importance of the imperfections of this report. The students receive their questions and report assessment at the beginning of the exam and prepare their answers by open book. They explain their answers orally and later use the blackboard to explain the formulae and create diagrams and graphs.
The duration of the exam (preparation and explanation included) does not exceed one half-day.
This standard assessment procedure can be changed by agreement with the students who will then be informed of any changes.
The assessment criteria are as follows: clarity, coherence, logic, rigor, precision, completeness, brevity, relevance, cross-cutting nature (within the course and between courses), quality of mathematical (mathematical meaning of the different coefficients of the equation, e.g.), physics (dimensions and units, order of magnitude - scaling, e.g.) and geographical (single and multivariate spacial and temporal interaction - type- and meaning of the variables e.g.) interpretations. Critical thinking with respect to the data used (qualification, nature, meaning, representativeness normalization ...) and methodological choices (justification of choice of methods, appropriate thresholds, ...) will also be taken into account when evaluation. Furthermore, answers will also be evaluated based on the quality and the originality of the graphic illustration since graphic expression is the scientist's specificity. It further allows demonstrating a good understanding of the phenomenon. Finally, enriching an answer with a wide personal scientific culture will also be considered a factor of excellence in the assessment. |
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Work placement(s) :
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| Nil |
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Organizational remarks :
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| Nil |
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Contacts :
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| Yves CORNET, Professor
Geomatics Unit, Allée du 6 Août, 17 (B5a), 4000 Liège
Tel. 04 3665371
Mail : ycornet@ulg.ac.be
Web: http://139.165.44.35/cms/index.php |
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| Items online : |
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| Course notes |
| The documents can be downloaded from the e-Campus of the University of Liege. |
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