GEOG0234-1

Duration

30h Th, 15h Pr

Number of credits

	Master in geography : geomatics and surveying (120 ECTS)	4 crédits

Lecturer

Yves Cornet

Language(s) of instruction

French language

Organisation and examination

Teaching in the first semester, review in January

Units courses prerequisite and corequisite

Prerequisite or corequisite units are presented within each program

Learning unit contents

Theory
I. Introduction (historical reminders, definition, aim)

II. Exploitation of one photograph
1. Characteristics of an aerial photograph
2. Geometric concepts of the central projectionFrame of reference
3. Perspective rays bundle and colinearity
4. Fundamental relationship of geometric optics
5. Distant object (p'=f)
6. Scale of the photograph

III. Exploitation of two photographs (stereoscopic pair)
1. Stereo-photogrammetry, reference frames, 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 equation of the parallax
VII. Exploitation of the transversal parallax equation
XIII. Creation of epipolar documents, automation of the search for homologous points, DSM and ortho-images production
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, DSM and ortho-images production

XIV. Accuracy of stereophotogrammetry

XV. Preparation of a mission

Practical sessions
Practical work sessions are carried out under controlled autonomy.
A stereo-pair of scanned photographs or digital aerial images, Ground Control Points with known 3D coordinate and the certificate of calibration of the photogrammetric camera are supplied to students.
They also have a series of practicables programmed in VBA by A. Collignon, DDPS software developed in our unit and Matlab and Octave codes implemented by Y. Cornet.
They are required to use the different software tools to carry out the different steps of the photogrammetric procedure. They must also perform the 3D restitution of some objects and validate the results. A comparison of the accuracy and précision resulting from this validation with the expected ones based on the geometric characteristics of flight and acquisitions on one hand and the calibration certificate on the other must also be performed.
The students will then have to write a report that will serve as reference for the evaluation of their theoretical knowledge.

Learning outcomes of the learning unit

The student will be able to
* Understand the geometric model for acquiring aerial photographs (perspective model - central projection).
* Understand the interest of calibrating the photogrammetric camera and the application of the calibration model during the inner orientation.
* Understand the formation of the 3D stero-model resulting from 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 for automated search for homologous points and the computation procedure of DSM and ortho-images.
* To apprehend the problem of a priori and a posteriori geometric uncertainty.
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 using professional software solutions that are generally available in this surveying domain.
This course is a prerequisite for the course "Supplement of photogrammetry" given during the 2d year of the Master. This specialized course will cover close-range photogrammetry (DLT, for example), aerotriangulation, satellite photogrammetry using linear digital sensors. During this specialized course, students will have the opportunity to program some solutions using Matlab, Octave or Python and to operate free photogrammetry software (MicMac developed for example).

Prerequisite knowledge and skills

The course uses notions of geometry and matrix calculus from the course of mathematics. Notions of geometrical optics from the physics courses and least squares adjustment from the numerical computation, statistics and error theory courses constitute another pre- or co-requisite. In addition, several notions from the remote sensing courses and the programming skill developped during the courses of computer sciences during the bachelor's degree are also exploited.
Finally, the way of thinking and analytical rigour developed during scientific courses of the bachelor's degree and secondary school also constitute advantages for those attending this photogrammetry course and who wish to reach the required performance level in the professional world.

Planned learning activities and teaching methods

The theory course is of the ex-cathedra type. Many reminders that are complementary 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 lessons which begins after the theory course are supervised and carried out autonomously. The emphasis is placed on the technical manipulation aspect of the 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 available software tools. At the end of the practical lessons, the students must write a report describing the technical procedures and demonstrating a good understanding of the meaning of inputs and outputs of each step. The specificities of the technical solutions suggested by each software tool must also be listed and explained.
It is also important to mention that the students can install the available software tools (MatLab et Octave Scripts, VBA executables, DDPS - Didactical Digital Photogrammetric Software, MicMac). These software tools and explanatory manuals for calculation methods are available on eCampus.
In order to analyse the reference data (elevation points), students are recommended to use the software program Quantum GIS.
In order to select homologous points on the images, they can use the free Erdas Viewfinder viewer or the Idrisi software made available. The user license for this software 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, the students can voluntarily discover different working environments than that of practical work.
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.

Mode of delivery (face-to-face ; distance-learning)

The teaching will be face-to-face.
The ex cathedra theory classes and autonomous and supervised practical lessons will take place according to the course schedule (http://www.facsc.ulg.ac.be/cms/c_253095/fr/horaires) in the room B5a/2/35 or B5a/4/18.
Presence at the practical sessions is mandatory.

Assessment methods and criteria

Permanent non-certificational evaluation and self-assessment are provided during the pratictical exercise sessions through a strong interaction between students and teachers.
Certificational evaluation is carried out orally. The questions asked to the student are inspired by imperfections of on the practical work report. The number of questions is a function of the severity of those imperfections. The students receive their questions and report assessment at the beginning of the exam and prepare their answers by open book. They then explain their answers orally using the blackboard to explain the equations and create diagrams and graphs.
The duration of the exam (preparation and explanation included) does not exceed half a 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 interpretations (mathematical meaning of the different coefficients of the equation, e.g.), physical interpretaions (dimensions and units, order of magnitude - scaling, e.g.) and geographical interpretations (single and multivariate spatial and temporal interactions - type - and meaning of the variables e.g.).
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 evaluating.
Furthermore, answers will also be evaluated based on the quality and the originality of the graphic illustrations 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 as a factor of excellence in the assessment.

Work placement(s)

Nil

Organizational remarks

Nil

Contacts

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

Items online

Photogrammetry
Photogrammetry

Photogrammetry