Computer Graphics and Human-Computer Interaction at the University of Zaragoza, Spain

Transcription

1 Computer Graphics and Human-Computer Interaction at the University of Zaragoza, Spain Abstract Francisco José Serón, Sandra Baldassarri, Juan Antonio Magallón, Pedro Latorre Grupo de Informática Gráfica Avanzada* Departamento de Informática e Ingeniería de Sistemas Centro Politécnico Superior University of Zaragoza {seron,sandra,platorre,magallon}@posta.unizar.es * This paper stems from the educational experience of the Research and Development (R+D) Advanced Computer Graphics Group (GIGA), which belongs to the Computer Systems and Languages Area of the Computer and System Engineering Department of the University of Zaragoza. The teaching activity focuses basically on Computer Engineering in relation to the group of subjects collectively known as Computer Graphics and on the subject of Human-Computer Interaction. The Computer Graphics group consists of three subjects. First, Computer Graphics, which describes the basis of synthetic image generation. Second, Geometric Modeling, which determines the shape of objects by means of mathematical and algorithmic model-description. And finally, Visual Modeling and Animation, which is concerned with the visual appearance of objects and their kinematics and dynamics. Human-Computer Interaction, on the other hand, provides insight into the design process of user-centered interactive systems. The lecturing of Computer Graphics group subjects is based on the learning methodology of problem-solving. Human-Computer Interaction, however, is taught following the behaviorist paradigm which, due to its informative nature, is based on master classes. The paper sets forth a general overview of our didactic approach to the fore-mentioned subjects, developing their aims, teaching methodology and assessment system. Also shown are their contents, practical sessions, evaluation of students performance, comparison with other curricular proposals, analysis of the academic results and recommended bibliography. Finally, few conclusions resulting from our teaching experience involving these subjects have been formulated. Keywords Teaching, Computer Graphics, Human-Computer Interaction, Educational Environment. 1

2 1 Work Environment Four Superior Engineering studies, postgraduate courses and Ph.D. programs are taught at the Superior Polytechnic Center of Engineers of the University of Zaragoza: Industrial, Telecommunications, Computer Science and Chemical Engineering. Their study plans are structured in two five-semester terms. The first one supplies the basic training. If we rule out freechoice subjects, optional possibilities are null or very limited at this level. The possibility of specialization becomes greater during the second term, in which numerous subjects can be chosen in order to have a diversified training or to center the studies around a specific specialty. The teachings which are the subject of this article can be chosen in all the studies, either as optional or free-choice subjects, although most of the students come from Computer Science Engineering. The distribution of Computer Science Engineering credits is shown in Table 1. 1st term core and mandatory credits st term optional credits (minimum to follow) st term free-choice credits nd term core and mandatory credits nd term optional credits (minimum to follow) nd term free-choice credits 18.0 Project Thesis 20.0 Total Table 1: Credit distribution in the Computer Science Engineering Studies Schedule Within this context, the subjects related with graphics taught at Degree Level are: Computer Graphics Courses: - Computer Graphics (CG): optional second-term one semester subject. The teaching load of the subject is 6 credits, 4.5 of which correspond to theoretic and problems classes, and 1.5 to practical classes. The course is included in the sixth semester, though the students generally take it during the third year of their studies. - Geometric Modeling (GM): optional second-term one semester subject, with a teaching load of 6 credits, 4.5 of which correspond to theoretic classes and 1.5 to practical classes. Prior study of CG is recommended, so students tend to course it in the seventh semester, during the fourth year of their studies. - Visual Modeling and Animation (VMA): optional second-term one semester subject, with a teaching load of 6 credits that is distributed into 4.5 credits of theoretic classes and 1.5 of practical classes. Prior study of CG and GM is recommended. The subject is included in the 9th semester, so students generally take it during the fifth year of their studies. Human-Computer Interaction Subject Human-Computer Interaction (HCI): optional second-term one semester subject. The teaching load is of 6 credits, 4.5 of which correspond to the theoretic part and 1.5 to practical classes. However, because of the restrictions on subject structures, all the hours are imparted as theoretical classes. 2

3 Students can gain access to this subject from the third year of their studies, but they usually do so during the fifth year. Project Theses in these thematic areas are available (examples of them are shown in Moreover, Computer Graphics-related teaching is imparted in Postgraduate studies and also in Ph.D. courses. For general information purposes, we have listed the most recent here: Postgraduate Studies - Communication in digital language: Image, Sound and Multimedia Technologies Ph.D. Courses - Solid Geometric Modeling - Fractals - Scientific Data Visualization 2 Computer Graphics Courses Description The main features of each subject that belongs to the Computer Graphics block are described in this section, itemized in the following order: didactic outline, contents, practical sessions, evaluation, comparison with other curricular proposals, academic results analysis and recommended bibliography. 2.1 Didactic Approach The didactic system is comprised of these four elements: the teacher, the students, a subject (in our case, Computer Graphics) and a medium. In this instance, emphasis will be placed on the knowledge pole. Traditionally, the problems involved in the teaching of a content are ascribed to the learning difficulties of students; the specific problematic that we intend to study emerges from the analysis of the teaching difficulties due to the very nature of the content developed in the classroom and the aims sought. The questions that the following conceptual framework attempts to solve are: What are the aims? How is the content to be developed introduced in the classroom? How should this knowledge be required in order to ensure that the student has learned it? Aims The course s main objective is to supply the student with the knowledge and abilities needed to develop a simple but complete graphic system on his or her own. This system has to have some basic features in the first version, and evolves continuously by incorporating the concepts that are consecutively explained during the three subjects that comprise the course. The specific aims of each subject are: Computer Graphics: This subject explains why and how the computer is used for graphics and synthetic image generation. Shape, color and movement are the milestones of the visual process and therefore, of the CG course. Our educational proposal seeks to give the student the basic 3

4 training necessary to familiarize him or herself, in a professional setting, with the possibilities that CG offers nowadays. Geometric Modeling: This subject explains how information on the geometric shape of any kind of object, either natural or artificial, is described in a conceptual, mathematical and algorithmic way, in order for a computer to interpret it. Visual Modeling and Animation: This subject explains how the information regarding the appearance and cinematic and dynamic state of any kind of object is described in a conceptual, mathematical and algorithmic way, in order for a computer to interpret it Methodology The old distinction between knowledge and know-how has a fundamental epistemological character, which remains relevant in any society. Some institutions are fundamentally scientific in nature, and built around knowledge while others are fundamentally technological in nature and are built around know-how. This separation reappears in educational institutions. It is commonly the case that this fact reflects itself within them, not just in the separation between theory and practice (between theoretical classes and problem-solving or workshop classes, as often occurs in faculties and technical colleges), but also in the wide range of ways of understanding practice, and specifically problemsolving, as a result of the epistemological model implicit in the institution. The approach suggested in this paper regarding the subjects under study intends to put an end to that dichotomy in the following manner: Each subject is a formal structure which constitutes an integrated perspective on knowledge and know-how in the computer graphics world. It develops a viewpoint which embraces the double allegiance of all knowledge to its more theoretical referent, which explains it, and to its more practical one, of which it is the application. For that reason, subjects are articulated around a description of terms such as task, technique, technology and theory, which will be briefly expounded on below. The notions of task and task types are at the root of everything. A task is usually represented by a verb which correlates to a wider anthropological concept that everyday language associates with a human activity. For instance, the overall task that each of the three subjects of Computer Graphics intends to fulfill would be: to build a conventional raster type system of visualization based on geometrical models expressed by way of polygons with the first one; to expand the first system by building a more general surface modeler with the second one, and to complete the system by expanding it with a Radiosity or Ray-tracing visualization algorithm with the third one. The student that has followed and passed the three subjects finally finds himself with a general system of his own, personalized according to his own interests and capable of generating synthetic images of complex scenes. The attainment of the necessary skills to solve the type of tasks we have mentioned requires a way of carrying out such tasks. A given way of doing receives the name technique (from the Greek tekhnê, to know how). Following the example of the computer graphics subjects, the necessary techniques would be those related to geometrical algorithms, visualization algorithms and animations algorithms. Increasing the level of abstraction, by technology we mean a rational discourse (logos) about technique (tekhnê), the primary goal of which is to rationally justify the technique to ensure that it allows the realization of the intended tasks, in our case, Technology related to Geometric Modeling, Visual Modeling and with movement or animation Modeling. 4

5 For its part, technological discourse contains more or less explicit statements, an explanation of which may be demanded. This leads to a superior level of justification-explanation-production, that of theory, which takes up the role regarding technology that the latter had regarding technique. In our case, it would be found in the world of Geometry, Optics and Mechanics. The status of what has been called theory here is in fact an ingredient of increasing abstraction, which grows and increases from the tasks to the techniques, the technologies and theories. As may be observed, in this form of organization of the subject, theoretical discourse is not opposed to practical activity (the task) as if they were two independent activities, each deriving its form from its own specific logic (as so frequently seems to be the case when analyzing the teaching practices in educational institutions). On the contrary, the didactic organization set forth makes the (dynamic) affiliation between theory and practice evident. Should the student analyze the educational surroundings he is immersed in, he or she will observe that around a certain type of tasks a tupla comprised of techniques, technologies and theories can be found. This type of logical structural organization follows the problems-theory structure although at a more refined level, appearing as a practical-technical block on the one hand, and as a technological-theoretical block on the other. To sum up, the didactic approach set out teaches students knowledge as the use of the part of scientific knowledge which is extracted and presented as the necessary technical knowledge to arrive at the solution of problems through know-how. This teaching methodology is rooted in problem-solving based learning [12] [13]. Problem solving is a process that requires the knowledge of a major discipline and of the techniques and skills needed to bridge the gap between the problem and the solution. Thus problem-solving is understood as a productive process in which the individual requires an incubation period followed by a sudden intuition through which the structure of the problem is mentally reorganized. In our environment, the initial problem is the Development of a Viewing System that must satisfy certain minimal features. Later, in the second year, the system must increase the ability to model the geometry and, in the third year, the system must increase the performance of the shading model employed. From a global point of view, it can be considered an open problem because it allows for a variable number of solutions (a different one for each student). The Problem-Solving process, as the teaching strategy for our subjects, forces the students to find the most suitable procedure for each case. Moreover, the process forces them to modify the point of view of their solutions as the technical possibilities change as they progress in their studies and elaborate their own knowledge. Success in this area allows the student to describe, interpret and justify all the components that constitute their own viewing system. The majority of the students doubts and problems arise during the development process of the part of the visualization system in which he or she is involved, and are normally solved by the student himself. Given that the work tool is a computer, this becomes the problem-solving tool, as the use of experiments and checking techniques is immediate. In this way, the learning-process becomes a highly interactive, individualized, flexible and autonomous process, in contrast to the more frequent present-day passive methods. Each group of students that follows the thematic group has the same professor throughout the three subjects (CG, GM and VMA) in order to give homogeneity to the contents, the explanation and the recommended bibliography. 5

6 2.1.3 Assessment System In these subjects, students apply the knowledge acquired through the development of a viewing system which allows them to know and link their theoretical study with real life systems, and which opens the doors of the exploration and innovation world for them. Regarding the assessment of students performance, emphasis is placed on the comprehension of the underlying concepts and the skills demonstrated by the system that the student submits, such as the completeness of the system, the quality of the scenes developed, the complexity of the models used, implementation efficiency, etc. 2.2 Contents and desired students level of expertise The contents of the Computer Graphics Courses are detailed in Table 2. In order to explain the student's desired degree of expertise, a key follows every subject. This key has been labeled as follows: I: Informative level. The student should be aware of the general ideas concerning the subject, and handle related software with fluency. A: Advanced level. Student should be able to read and understand a textbook related with the subject, and design and implement applications that carry on that issue. E: Expert level. Student should be able to read and understand an expert level paper related with the subject, to design and implement applications that carry on that issue and, in some cases, propose new or improved methods or algorithms. COMPUTER GRAPHICS GEOMETRIC MODELING VISUAL MODELING AND ANIMATION 6

7 Introduction (I) Presentation Human Perception and Computer Graphics Historic Evolution (I) Graphic Hardware (I) Output Devices Input Devices Graphic Accelerator Cards Basic ideas (A) Scan converting lines Polygonal Objects Modeling Elements involved in Image Definition Geometric Transformations (E) 2D Transformations 3D Transformations Geometric Projections (E) Planar Geometric Projections Parallel and Perspective Projections 3D Viewing Systems (E) Rendering (A) Face Culling Clipping Surface Culling Rasterization Basic Illumination Model (I) Graphic Standards Open-GL (A) RenderMan (I) Introduction (I) Presentation Historic Evolution Basic concepts of: Analytic Geometry (I) Differential Geometry (I) Interpolation and Approximation (A) Geom. Mod. of Euclid Objects: Curves (A) Plane Curves: Parametric and not parametric curves: Conic Sections. Space Curves: Spline, Bézier and B-spline Curves. Fitting and Subdivision. Parabolic Blending. Surfaces (A) Surfaces of Revolution. Sweep and Quadric Surfaces Bilinear, Ruled, Developable and Coons surfaces. Bézier and B-spline Surfaces. Fitting and Subdivision. Solids (I) Geom. Mod. of Fractal Obj. (I) Deterministic (Linear and Nor Linear) Random Implementation Techniques Direct Procedural Practical Examples Introduction (I) Presentation Historic Evolution Local Shading Models (I) The Local Equation Calculus algorithms Advanced Effects: texturing, roughness Global Shading Models The Rendering Equation (I) Algorithms for Shading Radiosity (A) Ray Tracing (A) Radiance Techniques (I) Colorimetry (A) Color Representation Color Models Device Independent Device Dependent Animation (I) Interpolation Direct and Inverse Kinematics. Restrictions Dynamic Behavior Control Table 2: The Computer Graphics Group subjects. Syllabus and desired student expertise level 2.3 Practical Sessions The behavior of the algorithms introduced in the subjects can be analyzed during practice sessions. The laboratory credits assigned in the course schedule result in a total of 5 practical thematic sessions, divided into 7 sessions of 2 hours each. 7

8 The contents of the practical sessions are shown in Table 3. CG GM VMA Practice 1 Introduction Curve Interpolation: Cubic Spline Local Shading Models: materials and sources Practice 2 Transformations I Curve Approximation: B-splines Practice 3 Transformations II Surface Interpolation: Coons Surfaces Practice 4 Basic Lighting Surface Approximation: NURBS Surfaces Simple Textures Advanced Textures Global Models: ray tracing in ALEPH Practice 5 Basic Shading and Materials Fractals: Julia and Mandelbrot Sets Global Models: radiosity in ALEPH Table 3: Practices of the Computer Graphics group subjects Practice sessions have been designed in order for the student to be able to attain two goals: First, to understand how the algorithms explained in class work and to analyze the possible implementation details that may be considered important. One of the goals of the practice sessions is to understand the low-level working of the algorithms. Second, to handle high level systems that implement their functionality based on the previously analyzed algorithms, in order that the student may analyze where each algorithm is used, how different high level systems encapsulate the said algorithms using a more or less friendly interface, and how they affect the output of these systems. Given the limited time that can be devoted to their use and the wide set of systems available, it was decided to lay more emphasis on those that are more easily available to the student, as is the case with low-level libraries OpenGL, leaving the rest at the level of guided use that may serve him or her as a double experience, that which is directly related to the concepts which are the object of the practice sessions and that which is related to the knowledge of the existence of commercial tools. The type of tools selected for the implementation of these practice sessions are: Standard low-level libraries for the generation of graphics in real time, which require programming knowledge. OpenGL was selected for practice sessions: it is a standard graphic geared toward low level handling of graphic accelerators and rendering over the said systems. Low-level commercial tools for the generation of high quality images. These are tools that allow the use of the full potential of the implemented algorithms and which allow for detailed analysis of the behavior of the said algorithms. Although they do not require programming knowledge, their interface is not suitable for use without prior knowledge of graphics. Libraries developed within the group for the generation of high quality photorealistic graphics. ALEPH is a photorealistic lighting and rendering simulation system developed and implemented by the GIGA group itself. It is based on the resolution of the lighting equation through MonteCarlo techniques. The system offers a series of high level programming libraries 8

9 (in C and C++) which allow the student to work with a complex simulation system, the level and quality of which is superior to present commercial systems. In this manner, the student can appreciate the problematics of a high level simulation system. Commercial tools with user-friendly graphic interfaces for the modeling and generation of synthetic images. These are commercial modeling, animation and rendering environments which allow the demonstration of integration in a single piece of software of many of the techniques mentioned with an interactive professional style user interface. Tools generated within the group and specifically geared toward teaching: MEIIGA (Material para la Enseñanza Interactiva de la Informática Gráfica Avanzada). MEIIGA is an interactive multimedia application for the teaching of subjects related to Computer Graphics and their possibilities. It follows the thematic distribution and the material developed to date for the teaching of the block s three subjects as well as incorporating new interactive material. The teaching goal is to allow improvement in the understanding of concepts through the showing in class of text and fixed images, the relation between concepts through hypertext and interactive examples. The present version, which is in fact at an advanced stage of its development, has been conceived as a tool for the teacher, replacing the traditional slides, and for the student, complementing the basic text. At a second stage, we intend to add material in order for the student to carry out practice sessions, and possibly some sort of self-assessment module. This varied set of tools allows the achievement of the goals previously mentioned. 2.4 Evaluation Didactic intentions (regarding the knowledge which is the object of this investigation) are made apparent in the curricula of the subjects adapted by the teacher for transmission in the classroom, so that what is known as effectively-classroom-imparted-knowledge comes into existence. After the instruction process and for evaluation purposes, the student must express his or her relative familiarity with the knowledge at stake. Thus we arrive at the last link in the transition from a didactic institution type of knowledge and it is possible to speak of effectively-classroom-learnedknowledge. To achieve this, two examinations are undergone in the three subjects: - A theoretical exam, in which the student s knowledge of basic concepts is evaluated. - An individual practical assignment, which is evaluated in an interview where the student demonstrates, with the aid of a computer, the performance of the viewing system that he/she has previously developed, while answering questions about the system or about the subject s concepts. The student passes if the examination is a success and if the individual assignment fulfills the basic requirements. The final qualification of the assignment depends on the system s quality and on the additional features implemented. To summarize, these are the requirements for each case: CG: Following a given viewing system pseudo-code based in polygonal geometric model a personal implementation must be done. The system must include a simple user interface and must allow the wire frame and Gouraud visualization. GM: Starting out from the viewing system previously developed during the Computer Graphics Course, a pre-processor that handles geometric models based in Bezier, B-splines, Nurbs and other techniques must be implemented. VMA: Starting out again from the viewing system previously developed, new suitable extensions must be added, or new viewing systems can be created. Usually, the students focus on one of the three following topics: texture mapping following any of the existing possibilities, implementation 9

10 of a new viewing system based in radiosity or implementation of a new viewing system based on ray tracing. A few examples of images generated with the viewing systems developed by the students throughout the three subjects can be appreciated in figure 1. Figure 1: Examples of images generated with the viewing systems developed by the students. Each of them focuses on an aspect that the author wished to emphasize: a)recursive lighting in ray-tracing systems. b)procedural Modeling of fractal elements. c)handling of complex and textured models. d)rendering of procedural primitives without explicit handling of polygonal models 2.5 Teaching and learning the most difficult topics The most important difficulties encountered in the transmission of knowledge may be classified in two groups: those that are due to a lack of scientific basis in the previous curriculum and those that are due to inherent conceptual difficulty or the level of knowledge demanded. The lack of previous knowledge of more than elementary Geometry forces the explanation of such knowledge from the outset. Therefore, part of the CG curricula and the greater part of GM are devoted to these issues. On the other hand this is also advantageous, because the concepts are introduced in a way which is totally geared to their application in Computer Graphics. The following subjects are part of this group: CG: Geometric Transformations, Geometric Projections. GM: Basic concepts of Analytic Geometry, Differential Geometry and Interpolation and Approximation 10

11 Geometric Modeling of Euclid Objects: Curves and Surfaces The case is the same for knowledge related to Physics (Optics and Mechanics), in particular the following concepts, which are imparted in VMA: The Rendering Equation Algorithms for Shading: Radiosity, Ray Tracing, Radiance Techniques Colorimetry: Color Representation, Color Models Animation: Interpolation, Direct and Inverse Kinematics. Restrictions. Direct and Inverse Dynamics. Initially, subjects are imparted in master classes, including many examples developed step by step. According to the students opinion, the most difficult concepts to understand are usually (reasons included): CG: - Geometric Projections and 3D Viewing Systems. Problems are due to the complexity of array treatment of transformations and projections. GM: - Basic concepts of Differential Geometry. Mathematical treatment is totally novel. - Geometric Modeling of Euclid Objects (Curves and Surfaces), problems are located in the comprehension of parametric representations. VMA: - Radiosity Techniques. The major difficulty lies in the technical complexity of its implementation. A problem common to all these subjects is the evident initial difficulty of imagining concepts visually on the part of the student. Most of the student s doubts and problems arise and are solved during the development process of the part of the visualization system he or she is involved with. In any case, the previously mentioned MEIIGA project, which allows visualization on the computer or classroom screen of texts, images and other audiovisual material, was embarked upon in order to assist the better comprehension of the subjects mentioned before. The most novel contribution lies within a collection of interactive examples which the teacher (or the student) may manipulate by modifying the definition parameters, points of view, lights, etc, while the relevant concept is being explained or studied, at the same time that the visual effect achieved can be observed. For example, when imparting the concepts of 3D geometrical transformations, MEIIGA allows working with a simple geometric shape, which is drawn in the upper part of the screen, while the transformation matrix appears in the lower part. Changes can be made with regard to the matrix s figures, choosing the operation (scaling, turn, etc) and the effect can be instantly seen, both in the matrix and in the figure. The examples used to explain the concepts of curves and surfaces also allow the modification of parameters (position and number of control points, weights, etc) and of the point of view from which the object is seen. Examples related to the concepts of VMA are presently being developed. The use of this tool during classes has been very welcome, and it has ostensibly improved the opinion (and results) of students. 11

12 2.6 Comparison with other curricular proposals Different courses related with Computer Graphics have been designed in universities of several countries [1 7]. For checking the correspondence of the topics explained in our three Computer Graphics subjects with other curricular proposals, the study mentioned in [14] is taken into account. The contents imparted in 23 institutions of the United States are compared therein. The following table shows the results of that comparison. The topic is indicated in the first column. The second column corresponds with the number of institutions where the topic is taught. And finally, the third one shows in which of our subjects (CG, GM, VMA) that topic is imparted, should that be the case. 12

13 Some contents are explained in the Human Computer Interaction (HCI*) subject, which is not included in the Computer Graphics curricula. Topic N Included in Topic N Included in Viewing transforms/ camera 19 CG Math foundations/review 5 CG/GM Hardware/terminology 15 CG 2D transformations 4 CG Lighting models 15 CG/VMA 3D rendering 4 CG/VMA 3D transformations 14 CG Fractals 4 GM User interaction 14 HCI* Coordinate systems 3 CG Object representation 11 CG Photorealistic methods 3 VMA Shading models 11 VMA Antialiasing 2 CG/VMA Color/color models 10 VMA Hidden-line removal 2 CG Curves 10 GM Pipeline details 2 CG Hidden-surface removal 10 CG Virtual reality 2 HCI* Rasterization 9 CG VRML 2 HCI* Implementation particulars 7 CG/GM/VMA 2D ray tracing 1 Supporting data structs/models 7 CG/GM/VMA Computational geometry 1 GM Texture mapping 7 VMA Global illumination 1 VMA Clipping 6 CG Interactive internet app. 1 HCI* Ray tracing 6 VMA Projections 1 CG Surfaces 6 GM Scientific visualisation 1 2D drawing 5 CG/GM Shadows 1 VMA Animation 5 VMA Time-critical applications 1 Table 4: Summary of the topics imparted in Computer Graphics, according to [14]. Columns show the topic, the number of institutions where topic is imparted and their correspondence with the courses imparted in the CPS. As can be appreciated, courses cover all the issues most frequently imparted in other institutions in regard to Computer Graphics. 13

14 2.7 Level of acceptance of the methodology employed A simple definition of quality for these courses is the correlation between the training goals defined in the specifications (requirements) and the measurable goals finally achieved by the students that took part in the learning process developed during the relevant course. The satisfaction and fulfillment of students and teachers expectations must be taken into account when the moment of measuring the quality of the course arrives. Universities, just like any other contemporary organization, require a rapid and accurate process allowing them to attain a flow of information on results, preferences and behavior of their target population; therefore, opinion polls are an essential tool in the search for this information, which is vital for making safe decisions in such complex environments as are those which belong to the area of training. In order to assess the chosen methodology s level of acceptance (both in teaching and in evaluation) on the part of students, the results achieved in the polls carried out throughout the entire university within its annual teaching quality measurement plan are shown here. The results achieved in the opinion polls of the entire university within its annual plan for the measurement of teaching quality are shown in order to assess the level of acceptance of the methodology used on the part of the student body, both in teaching and evaluation. The polls have been designed by the Insitute of Educational Sciences of the University of Saragossa; they are carried out at the end of each four-month period, prior to the assessment of each subject and following rigorous procedures of information control. Aspects which these polls intend to quantify are related to: What (goals expressed in contents, knowledge, skills, competence, comprehension goals, among others). How (the method, the assessment system, the grading system). Context (activities, learning spaces). The appropriate relationship between these aspects is what provides coherence to the course designed and developed under the guidance of a teacher. The average values corresponding to the subjects of Computer Graphics, Geometric Modeling and Visual Modeling and Animation are shown in the following tables in comparison with the remaining the subjects imparted in the Area (Definition of Area: Computer languages and systems, 40 different subjects), the remaining subjects imparted by the Department (Definition of Department: Size of the sample, 62 teachers, 2 areas of knowledge) and all the subjects imparted in the Center (Definition of Center: size of the sample students, 15 departments, 30 areas of knowledge, 335 teachers). Question: the student attends classes: (1) regularly (2) frequently (3) occasionally (4) minimally CG GM VMA Area Department Center Question: The goals and contents of the subject have been defined: 14

15 (1) with great precision (2) with considerable precision (3) somewhat imprecisely (4) vaguely (5) they have not been defined CG GM VMA Area Department Center Question: You consider this subject: (1) very difficult (2) difficult (3) reasonably difficult (4) easy (5) very easy CG GM VMA Area Department Center Question: You consider the extent/scope of the programme to be: (1) very broad (2) broad (3) adequate (4) limited (5) very limited CG GM VMA Area Department Center Question: Regarding your training, you consider the contents of the subject: (1) very important (2) important (3) of some importance (4) unimportant (5) irrelevant CG GM VMA Area Department Center Question: Material recommended by the teacher (1) excellent to (5) very inadequate CG GM VMA Area Department Center Question: Coordination between the theoretical part and the subject s remaining activities (1) excellent to (5) very inadequate CG GM VMA Area Department Center Question: Teacher s command of the material imparted (1) excellent to (5) very inadequate CG GM VMA Area Department Center Question: Use of didactic means and resources (1) excellent to (5) very inadequate CG GM VMA Area Department Center

16 Question: The subject s assessment criteria have been defined: (1) with great precision (2) with considerable precision (3) somewhat imprecisely (4) vaguely (5) they have not been defined CG GM VMA Area Department Center Question: the application of theoretical concepts in practice sessions is (1) excessive (2) frequent (3) adequate (4) scarce (5) insufficient CG GM VMA Area Department Center Question: Does the programme overlap with other subjects? (1) no (2) only by way of reference (3) minimally (4) significantly (5) excessively CG GM VMA Area Department Center Taking into account that teaching and assessment methodologies are different from those of the remaining area, department and center, the polls carried out prove that the students are satisfied with the subjects taught in the computer graphics block and with the methods used, and this is reflected when comparing the results of the polls: the graphics block always gets better marks. 2.8 Academic Results Analysis During each academic year, students have three possible exam dates, of which they may use two. If the subject belongs to the first semester the possible dates are within the following months: February, June and September. If the subject belongs to the second semester the dates will be in June, July and September. Table 5 shows the historical evolution of the number of registered students, the percentage of students who passed during each call for exams and the total results in the Computer Graphics group of subjects during the period from 1994/95 to 1999/2000. Registered 1 st Exam 2 nd Exam 3 rd Exam Total CG % % % % CG % % % % GM % 7.69 % % % CG % 4.39 % % % GM % % % % VMA % % % % CG % 8.54 % % % GM % % % % 16

17 VMA % % 9.68 % % CG % 4.61 % % % GM % 7.27 % % % VMA % % % % CG % 4.29 % % % GM % 6.66 % % % VMA % 3.12 % 50 % % Table 5: Registered students and percentage of students who took each exam in the three subjects The following conclusions may be reached by analyzing the table: The average number of students registered in each course is 100, the subject of Computer Graphics is very popular and most students take it. The subject is useful for them to increase their global knowledge in relation to the overall knowledge related to Computer Science. Students who take the other two are those who have a greater interest and are more inclined towards computer graphics. The evaluation methodology by means of an assignment makes most of the students sit the exams after summer, during the last examination call. Although all the subjects in this block are optional, the average percentage of students who attended is considerably high, 65.49%. The qualification distribution obtained over the total number of students who sit the exams in each subject can be observed in Table 6. 17

18 D - E C B A CG % % % CG 7.02 % % % % GM % % CG % % % GM % % % VMA % % % CG 3.28 % % % 3.28 % GM % % % VMA 3.57 % % % % CG % % 4.88 % GM % % % VMA % % CG % % % GM % % % 9.53 % VMA % % % Table 6: Distribution according to the obtained marks in relation to the total number of students took the examinations. Students usually hand in good quality practical assignments as well, and generally receive high scores: B or A. 2.9 Recommended bibliography for the students of Computer Graphics Subjects The recommended bibliography for the student is based on selected chapters of the following bibliographic list can be classified in two blocks: Core level and Advanced level Core level: At the end of the courses, the student should know the ideas contained in this type of books Foley J. D., van Dam A, Feiner S. K., Hughes J. F.: Introducción a la graficación por computadora, Ed. Addison-Wesley Foley J. D., van Dam A, Feiner S. K., Hughes J. F.: Computer Graphics. Principles and Practice. Second Edition, Addison-Wesley This is a very general book dealing with practically all aspects of computer graphics. It could almost be considered the Bible of mandatory reference of all subjects (available in English and Spanish, althoug spanish edition is a reduced version of the original). Hearn D., Baker M.P.: Gráficas por computadora. 2ª edición, Ed. Prentice- Hall Like Foley s book, an overall guide but less in-depth on certain subjects. 18

19 Rogers A.: Mathematical Elements for Computer Graphics. Ed. McGraw-Hill. Second Edition, Introduces the necessary basics for the handling of the mathematical elements which appear in the geometric modeling subjects: vectors, transformations, curves, surfaces. Watt A., Watt M.: Advanced Animation and Rendering Techniques. Addison-Wesley, Watt A.: 3D Computer Graphics. Addison-Wesley, Both these books include the majority of concepts used in the courses taught. OpenGL Architecture Review Board OpenGL Programming Guide, Addision-Wesley, The OpenGL reference book. Not a mere command reference manual; it describes the necessary steps in order to apply the available techniques in OpenGL to achieve the desired visualization. Advanced level: At postgraduate level interested students may continue studying the ideas contained in these type of books. Glassner A.S.: Principles of Digital Image Synthesis. Volúmenes I y II. Morgan Kaufmann Pblsh. San Francisco, Offers a compendium of the theoretical basics necessary for the generation of fotorealistic images, from the theory of color, light transportation systems, to advanced visualization algorithms such as radiosity, ray-tracing o global lighting algorithms. Rogers A.: Procedural Elements for Computer Graphics. Ed. McGraw-Hill. Introduces the better known rendering procedures at algorithmic level. A difficult book. Mäntyla M.: An Introduction to Solid Modeling. Computer Science Press, One of the few books which elaborates on matters relative to solid modeling. A complex book. Barnsley M. F.: The science of fractal images. Springer-Verlag, This book introduces fractal modeling methods, and offers the necessary mathematical basis, as web as introducing many examples to absorb complex concepts, for example the fractal dimension. Ebert D.S.: Texturing and Modeling. Academic Press, Focuses on advanced texturing and shadowing methods, dealing with procedural techniques: definition of advanced lighting and texturing models. 19

20 3 Human-Computer Interaction Subject Description The main features of the Human-Computer Interaction subject are described in this section, listed in the following order: didactic approach, contents, practical sessions, evaluation, comparison with other curricular proposals, academic results analysis and recommended bibliography. 3.1 Didactic Approach Aims The general aim of the Human-Computer Interaction subject, included in the Information Systems thematic block of subjects, is to offer the student a perspective on the world of user-interface engineering, describing its possibilities, principles and analysis, design and implementation methods. Students come to the subject without any previous knowledge of the concepts and methodologies relating to human-computer interaction. Due to this lack, and to the range of topics involved and their rapid and continuous evolution, this subject attempts to give a wide and global vision of the new technologies, so that students interested in these topics can work and research later by themselves, having been provided with the necessary foundation, terminology, reference for information research, etc. Besides the general aims commented before, the specific objectives of each part that constitute the subject are the following: Principles of Interface Design for Human-Computer Interaction: This part deals with the basic processes of acquisition and processing of information by human beings. The introduction of the analysis, design and evaluation techniques of user interfaces is established on this basis. Architecture and Implementation of the Graphic User Interfaces: This part presents the existing basic concepts and development methods for the construction of applications that interact with the user through a visual interface. The topics the students are intended to absorb focus on the several methods of inner performance of user interfaces (IU), the philosophy of programming an application based on a graphic interface and the different development and support programming systems. Multimedia Systems and Applications: The objective of this part is the study of the different elements that constitute a multimedia application: text, graphics, sound, image, video and databases. The student is also intended to absorb the methodology of multimedia project development, the physical devices that can be used and the software tools for the integration of the fore-mentioned elements. Multisensorial Systems, Virtual Reality and Augmented Reality: This part attempts to allow the student to identify all the elements and components required for solving a problem by using immersive techniques, with ease and in a systematic way. The most recently published experiences must be familiar to the student, who ought to be aware of specific applications Methodology This subject is characterized by a remarkable variety of present-day contents, taught in a very short time period, as its teaching load is restricted to 60 hours. That is why the subject was divided in four thematic parts, and the pure master class technique (behaviorist paradigm) was adopted as didactic methodology [15] [16]. 20

21 Clear lectures for pointing out the basic principles are adequate for the introduction to a new subject and for presentation of subjects not included in books. They are valuable as a source of discussion of problems and possible solutions and are considered the best method for difficult subjects in which aid is essential; they are also the most economical way of updating subjects that can easily become obsolete. Moreover, they allow access to larger audiences Assessment System A theoretical examination, in which the basic knowledge of the four parts of the subject must be demonstrated, is used to test the students performance. Likewise, a practical assignment, which assesses the student s capacity for innovation, research and problem-solving, must be undertaken and handed in. 3.2 Contents and desired students level of expertise The Human-Computer Interaction contents are described in Table 7. HCI Part 1: Interface Design Principles for Human-Computer Interaction Part 2: Architecture and Implementation of Graphic User Interfaces Part 3: Multimedia Systems and Applications Part 4: Multisensorial Systems, Virtual Reality and Augmented Reality Introduction: Human, Computer, Interaction Practical Principles of the UI design: Analysis, Design, Implementation Evaluation: The Standards and their Applicability Development of User Interfaces for Networking: Languages, Style Guides and Interface Evaluation 2D Interaction Systems Based in Windows Software Architecture of the Window Systems: Client-Server Programming Paradigms: Event Loops and Notification Standard APIs and 2D UI Programming Development Systems for UI Advanced Topics: 3D User Interfaces and Net Interfaces Introduction and General Description of the Multimedia Elements Interactivity, Text, Graphics, Data Bases Image, Audio and Video: Acquisition, Compression and Processing Design and Production of Multimedia Applications Project Development Present and Future Areas of Development Historical Introduction Virtual Reality (VR) Definition VR Devices Architecture for the VR Systems Evaluation of the VR Systems Applications Augmented Reality Table 7: Syllabus of the Human-Computer Interaction Subject The required students expertise is at informative level for the entire theoretical content, and advanced or expert level for the issues chosen in order to complete the final course assignment (see evaluation). 21

22 3.3 Practical Sessions The variety and range of topics imparted, added to the lack of necessary infrastructure, poses difficulties for including all the contents in practice sessions. The practical mastery of the concepts studied is acquired during the realization of the final course assignment, as described in the following section. 3.4 Evaluation Two examinations are established for evaluating and measuring the information received by the student. A theoretical exam on the basic contents graded either as suitable or not suitable. General questions on all the topics explained in class are included. A final course assignment in one of the 4 areas. These tasks can be classified in two groups: - Theoretical: Research and documentation tasks regarding new products and techniques related with the contents belong to this category. - Practical: The use and integration of tools described in class. The material used varies considerably depending on the kind of work and the area selected. Theoretical work is distinguished by a great effort in the search for recent bibliography (books and magazines) and Internet information. Practical work focuses on the use of specific tools or methods described in class. In both cases tasks can be suggested either by the student or by the professor. A few of the assignments carried out in each block during the years in which the subject was imparted can be seen in table 8. 22

23 Human Computer Interaction Part 1: Interface Design Principles for Human- Computer Interaction Part 2: Architecture and Implementation of Graphic User Interfaces Interfaces design using a style guide and a previously designed evaluation method. The 9241 ISO standard and its application in Internet based environments Lo-Fi techniques application to the design of a domestic electronic system interface Website design Development systems comparison: the use of several toolkits (Qt, Gtk, Jx, Vx, ViewKit) when an application is developed Portability studies: available tools for different platforms Implementation of a graphic interface over textual oriented applications Part 3: Multimedia Systems and Applications The use of authoring tools for developing of CD-ROMs Animation techniques: comparison and exemplification Comparison of audio systems and their compression methods Implementation of image compression Part 4: Multisensorial Systems, Virtual Reality and Augmented Reality Immersive environments and simulation Real time visualization over large scenarios Virtual reality and education Immersive environments and spare time Immersive environments and medicine Architecture, revisualization and virtual reality Augmented reality experiences Table 8: Assignments carried out in the Human-Computer Interaction subject. The final assignment allows the teacher to evaluate the knowledge acquired on a specific topic, as well as originality in the resolution and the process used by the student regarding data selection, abstraction and coding, application, analysis, synthesis or generalization of knowledge, memory, etc. The teacher of the corresponding part, who revises the contents, the depth of the work and the clarity of its exposition, assesses each work first. Afterwards, a group revision is done, so that all the teachers can have a global vision of the works handed in and the mark of the student can be determined. 23

24 A few examples of final assignments can be seen in figure 2. Figure 2: Examples of final assignments of the HCI students. Each of them focuses on the area which the author decided to emphasize:a)interactive multimedia presentation. b)web page on digital sound. c)presentation on special effects in cinema. d)presentation on static image and digital treatment of images 3.5 Teaching and learning the most difficult topics Given that the content of the subject is fundamentally informative, no important difficulties in the absorption of knowledge have been registered. On the other hand, the subject is usually taken during the tenth and last semester of the degree course, when the strudent s training in related matters (Programming, Computer Graphics, Software Engineering) is already very advanced. 3.6 Comparison with other curricular proposals 24