WWW as a source supporting computer graphics studies

Abstract. A short survey of existing learning material in the Web for introductory computer graphics courses is given. A bilingual (partly Finnish, partly English) hypertext and hypermedia interface to the Web-material is designed and implemented. The merits and dismerits of the approach are discussed.

1 Background and motivation

The main pattern has been unchanged since the 80's. We have observed similar conservatism all over the world. The contents and the structure of the most widely used textbooks, such as Newman&Sproull [12], Hearn&Baker [6] and Foley&vanDam&al [4] are very similar, and most introductory computer graphics courses are based on these texts. Perhaps this reflects the fact that teaching computer graphics is a tedious task.

However, a tremendous progress in hardware, algorithms and applications is going on in an accelerating manner. Powerful networked personal computers are now available for every student. The needs of graphics education have changed. Also the pedagogical views of learning and teaching have changed as the results of cognitive psychology and costructivist learning theories have been widely accepted. The role of computers in education has changed [10].

So, there is a need to reorganize both the contents of the introductory computer graphics course and also the ways of teaching it. New techniques and ideas are needed for using computers and computer graphics in this education. Interactive courses and multimedia presentations can significantly improve learning in graphics courses. But how to tackle these problems? We know a few published attempts [15, 20, 17, 16].

The benefits of computer support in teaching and learning are now widely accepted. Interactive computer courses and multimedia presentations can significantly improve learning [1]. But producing high-quality material for computer based education is, and will continue to be, tedious and very time consuming and expensive. Widespread use and reuse of high-quality basic learning materials is the most practical way to share the costs for the development of these computer based learning environments [7].

It is a general belief that the Web offers limitless research opportunities for the students, and the educational uses of the Web are widespread. The latest advances in computers should be available in the Web. Is it thus possible that the Web already contains the study material needed? Guided by this question we decided to make an inexpensive preliminary experimental study which consisted of two parts:
1) a short survey of existing materials in the Web supporting teaching and learning of introductory computer graphics, and
2) a hypertext and hypermedia implementation of an interface that will encourage the students to use the diverse learning material already available in the Web.

The project has been financially supported by the Faculty of Science.

2 An overview of materials in the Web

A thorough surveying throughout the Web resulted a long list of interesting material although not all Web sites visited are worth mentioning. The most relevant sources are given in the Appendix: Material for computer graphics education.

The Web offers learning environments and fragments of learning materials available at scattered sites for free usage. Some of the programs are for self study, others are demonstration software to be used in a lecture. Some cover almost the entire graphics course. Part of the software are just for visualizing some minor concept, such as a line drawing algorithm.

The two large-scale projects HyperGraph [13] and Graphica [2] (see Appendix) cover the introductory computer graphics course. Both hypermedia projects have run for years, but are still under construction and not ideal as an only study material even though they have been used as a primary text [14, 2]. The material does not essentially differ from ordinary text books, probably due to high production costs of a meaningful interactive hypermedia.

A few interactive software are also available from the Web. They focus on a limited field of computer graphics. Therefore, it has been possible to finish them to serve the purpose they were designed for. Worth mentioning are Rosalee Wolfe's TERA [19], Indira Vidyaprakash's Camera and Perspective Transforms, and Dino Schweitzer's demonstration programs [18] (see Appendix). In addition to interactive material, there are also several lecture notes and slide shows available. Some of these sets are of high quality. Good examples are SIGGRAPH slide shows and lecture notes from the Universities of Waterloo, Toronto, Manchester, Stanford and Brown (see Appendix).

3 A simple interface to the best materials in the Web

A plain list of links is not a satisfactory user interface for the students to study the diverse Web-material. It is tempting to build a learning environment to the Web because the wide accessibility is combined with the ease of use.

As the Web is not designed for educational purposes, there are only a few attempts to provide such an environment and even fewer successes [9]. However, it is clearly possible to create a comprehensive and pedagogically meaningful learning environment, if the content is previously fixed.

We have designed a simple interface to the graphics material chosen from the available Web resources (available at http://www.cs.helsinki.fi/group/goa/). The original material is left unaltered, but sometimes copied at our site in order to avoid long transfer times and to prevent changing links. The implementation supports lectures as well as serves as a source for independent learning and reviewing.

Our starting point has been a learning process model. In a Web-based learning environment, as well as in other more traditional learning, much of the learning efficiency is dependent of a well defined learning process. The process itself can be divided into six stages [3]. Motivation means connection of studied topic to the previous learned material. In our case, motivation can be provided by telling how computer graphics is connected to the other areas of computer science. Orientation is to get an overall picture of the topic. In our opinion, this could be provided with the usage of a concept map showing relations of various concepts within the field of computer graphics. Internalizing is the actual learning of the topic. For this part of the process, existing texts and pictures from the Web-material are used.

The last three stages of the learning process demand interactivity. Externalizing means to apply the gathered knowledge to other situations. This could be provided also by the interactive programs available from the Web. Evaluation means to evaluate learning and a possibility to revise a certain topic when needed. A possible solution to this stage could be to offer several different clarifications of the same topic so that the student can view the topic from various viewpoints. Comparing has to be done to determine whether the learning goals have been met. This is particularly important when the system is used for self-study. Comparing could be done by interactive programs, or simply by questions and answers found from the Web resources.

The logical structure of our learning environment is based on the learning process. To ease the access to the learning environment for Finnish students, the logical structure consists of two levels. In the upper level, there are introductions to various concepts in Finnish. The aim is that the student become familiar with the Finnish terminology and vocabulary. At the same time these pages show a guided tour through the material. In the lower, more detailed level, there are full illustrated explanations extracted from the Web (Figure 1). To avoid the possibility to be lost in a hyperspace, all the navigation takes place in the upper level and there are no links between pages in the lower level.

In addition to a guided tour, the starting page contains links to the concept map, glossary, and help pages.

Figure 1: Two-level structure of the learning environment.

4 Difficulties in implementation

When we started to plan the implementation, we already knew on the basis of J. Kurhila's thesis work [8] that the Web contains much ready-to-use material to support both the teachers and the students tasks. However, there were several difficulties related to the usage of this material.

Difficulties in creating the learning process. Intentional plan of the subject matter and contents is often considered the most important factor in designing beneficial computer-assisted learning. Our design principle was to collect ready to use material from the Web and integrate it to our learning environment without alterations. Also, our intentions were to provide a learning environment where the content is of equal quality. The material in the Web is yet versatile and of different quality. If we had wanted to provide constant quality, we would have been forced to write or at least revise most of the material, because there were good material from only the most essential concepts of computer graphics. Thus, it was not possible to use a detailed pedagogical plan to construct a complete course material. The result is characterized by the accidental content of the Web.

The integration of the existing material is also problematic. For example, different terms are used for common concepts, and prerequisites are prone to vary from a source to source.

Confirmation of learning. In computer-based learning environments, there are often too few possibilities to confirm learning, even though it does not require interactive programs. Simple questions and answers are sufficient. However, there are not many Web-sources that contain questions and possible or model answers. To produce pedagogically reasonable questions is a laborious task. Therefore, we were not able to include sections which offer opportunity to confirm learning.

Lack of interactive material. One main advantage in computer-based learning environments compared to classical classroom setting is the ability to involve true interaction. It is possible to provide programs that allow learning by experimenting. There are ways to ease the understanding of a difficult concept with interactivity (e.g. concepts such as 3D view transformation). Therefore, it is a pity that valuable programs are device dependent. Only a few Java programs exist which can be used as a part of a meaningful learning process.

Limitations in HTML. WWW and HTML have not been developed for educational use. It is impossible to construct learning paths similar to the traditional computer-based learning environments. Also, HTML lacks text formatting options and does not support mathematical symbols and equations. Some of these limitations could be solved with expert programming.

The absence of software tools to create Web-based learning environments caused problems when altering the visual appearance or the structure of the environment, as well as constructing a concept map of computer graphics. Efficient Java-based tools have not been available until just recently.

Question of copyright. To reuse and publicly present material other than own requires a permission from the copyright owner. We found that it was not difficult to receive a permission to use material, as long as it was used for non-profit educational purposes. However, the copyrights should be paid more attention to than usually offered.

5 Conclusions

In principle the Web offers the required possibilities to implement learning environments of high quality and flexibility, which will follow pedagogic plans and satisfy the different demands of large user groups. Hypertext and hypermedia encourage the use of diverse study materials and methods. It is still a tedious task to plan and implement such an environment. Easy to use and flexible assisting software tools are lacking. A large team of many types of experts is needed. The process will be very time consuming and expensive. Are such huge systems really necessary?

Probably the only solution would be a world wide shared effort of collaborative teaching in computer graphics. However, it must be carefully planned, coordinated, and conducted. The participants must obligate themselves to their chosen subtasks. The maintenance will be a problem in the rapidly changing computer world. Only a loose connection between the parts is possible. Our experiment is a modest trial to see what is possible when using existing material and implementing nothing but an interface.

Our experiences have been both positive and negative. From the students' point of view the accessibility of the Web-material is better although at the moment the students' reactions are missing. Web presentations offer alternative approaches, notations, terminology and supplementary readings to the text book material. This will force the student to reconsider his/her understanding. However, the non-uniform presentations are of course disturbing. The missing parts should be added. Especially a large collection of exercises and problems with hints and answers for self-assessment are needed. Anyway, we think that our experiment has been worth doing.

The reuse and loose coupling of existing materials have many drawbacks. The presentation of the material is not uniform. The present material is mainly quite old and not originally planned for the Web-use but merely an automatic transformation of old notes to the Web-format. The material does not cover all the required topics. The interactivity and hypermedia features are not fully used. Active participation, group work and shared cognition during studies are not supported.

References

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D. Carlson, M. Guzdial, C. Kehoe, V. Shah, and J. Stasko. WWW Interactive Learning Environments for Computer Science Education. ACM SICGSE Bulletin, 28(1):290-294, 1996.

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J. Foley, A. van Dam, S. Feiner, J. Hughes, and R.L. Phillips. Introduction to Computer Graphics. Addison-Wesley, 1994.

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J. Kurhila. Graafisen tietojenkäsittelyn opetus ja opetusmateriaali World Wide Webissä. M.Sc. Thesis, 1997. Department of Computer Science, University of Helsinki, C-1997-26.

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J. Kurhila. Verkkokäyttöiinen tietokonegrafiikan oppiaineisto. In M. Rahkila and T. Takala, editors, Tietokoneavusteinen opetus, pages 121-132. Department of Computer Science and Engineering, Helsinki University of Technology, TLM-C1, 1997.

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Appendix: Material for computer graphics education

Teaching computer graphics using hypermedia

Graphica - A course of computer graphics in WWW http://www.cc.gatech.edu/gvu/multimedia/nsfmmedia/graphics/edulib/CSA.html

Computer Graphics On-Line (in X-windows environment) http://www.cs.curtin.edu.au/units/cg252-502/notes/.index.html

Educational computer graphics Java applets

Demonstration of usage of BSP trees to solve hidden surface elimination (Brown Univ.) http://numinous.com/_private/people/pjl/graphics/bsptreedemo/bsptreedemo.html

A ray tracer written in Java for educational purposes (Brown Univ.) http://www.cs.brown.edu/people/dlg/java/trace/home.html

Bezier, hermite and B-spline curves (Simon Fraser Univ.) http://fas.sfu.ca:80/1/cs/people/GradStudents/heinrica/personal/curve.html

DDA- and Bresenham-algorithms for generating lines (Curtin Univ. of Tech, Australia) http://www.cs.curtin.edu.au/units/cg252-502/notes/bres1.html

Excellent applet on 3D viewing (Cornell) http://www.tc.cornell.edu/Visualization/contrib/cs490-95to96/indira/Camera.html

Visualizing surfaces (Cornell) http://www.tc.cornell.edu/Visualization/contrib/cs490-95to96/seena/Project/User/

Visualization of 3D-transformations (Univ. of Toronto) http://www.dgp.toronto.edu/people/van/courses/csc418/applets/trans/trans.html

Tutorials on modelling transformations, curves and surfaces (Utah) http://www.cs.utah.edu/~bbachman/gtutor/

Material for computer graphics teachers and students (e.g. lecture notes)

Manchester University: ITTI Gravigs - Texts, notes and demonstration software (PostScript, software SunOS, HP-UX)
http://info.mcc.ac.uk/CGU/ITTI/gravigs.html

SIGGRAPH Slide Sets 1991 and 1993 (GIF-pictures)
http://www.siggraph.org/publications/slide-set/slide_sets.html

Univ. of Washington: Introduction to Computer Graphics course material (PostScript)
http://www.cs.washington.edu/education/courses/457/

Carnegie Mellon University: Computer Graphics 2 course material (PostScript)
http://www.cs.cmu.edu/afs/andrew/scs/cs/15-463/pub/www/notes.html

Univ. of Princeton: Computer Graphics course material (html)
http://www.cs.princeton.edu/courses/archive/fall95/cs426/lectures/index.html

Univ. of Waterloo: Introduction to CG course material (html)
http://www.undergrad.math.uwaterloo.ca:80/~cs488/ln.HTML/html.html

Univ. of California, Davis: Computer Graphics - on-line notes (html)
http://graphics.cs.ucdavis.edu/GraphicsNotes/Graphics-Notes.html

Arizona State Univ: Introductory Computer Graphics course material (html)
http://www.eas.asu.edu/~cse470/

Florida Institute of Technology: CG course material (html)
http://cs.fit.edu/courses/cse5255/thesis/index/index.html

Brown University: CS 123 Introductory Computer Graphics (PostScript)
http://www.cs.brown.edu/courses/cs123/lectures/index.html

CG Online Notes, University of Toronto (html)
http://www.dgp.toronto.edu/people/van/courses/csc418/fall96.html

Stanford University: CS 248 Introduction to Computer Graphics (PostScript and html/GIF)
http://www-graphics.stanford.edu/courses/cs248-96-winter/Lectures/

Oregon State University: CS 450/550 Introduction to Computer Graphics (PostScript)
http://www.cs.orst.edu/~tgd/classes/450/450.html

Berkeley University: CS 184 Foundations of Computer Graphics (html)
http://www-inst.eecs.berkeley.edu/~cs184/

Introduction to C++ and Computer Graphics (html) (Univ. of Limerick, Ireland)
http://www.ul.ie/~flanagan/ce4704/ce4704.html

Central Queensland Univ., Australia: Computer Graphics (html)
http://138.77.37.27/HomePage/Rons/html/contents

Worcester Polytechnic Institute: Advanced topics in Computer Graphics (html)
http://cs.wpi.edu/~matt/courses/cs563/

Software to ease computer graphics education

MRT - software to ease graphics programming in a graphics course
http://hyperg.cs.uni-bonn.de/0x83dc0a3a_0x0001f9a8

uisGL - A portable toolkit of C++ classes to support computer graphics education
http://www.uis.edu/~grissom/UISGL/Welcome.html