Magdy F. Iskander, J. Corey Catten, Antony Jones, Rex Jameson, and Albert Balcells
CAEME Center
College of Engineering
University of Utah
Salt Lake City, Utah 84112
Recent studies show that computer-aided instruction (CAI) provides a significant opportunity to improve the quality of teaching profoundly and cost-effectively. It has been reported that CAI may present a 50 percent increase in retention, a significant improvement in the learning rate, an increase in course completion, and a decrease in the overall cost of education, particularly when distance learning is involved. Based on these statistics and as the computer technology, simulation tools, and graphics software continue to grow, expand, and improve, the development of technology-based educational tools-interactive multimedia software-is not only justifiable but also commendable [1].
Technology-based education is expected to significantly change curricula structure and offerings, change the development of teaching laboratories, and even influence the role of a university faculty in classroom teaching. In addition to the traditional utilization of computers for number crunching, the solution of a large system of equations, and the graphical display of results, there has been a recent move to use the power of high-performance computing to teach physical sciences and engineering based on fundamental and basic principles rather than by using mathematical models and equations [2-3]. One such project is known as the CoLoS (Conceptual Learning of Science) USA project founded by the Hewlett-Packard Company in collaboration with the CAEME Center for Multimedia Education and Technology. Eleven universities-including Massachusetts Institute of Technology, Northeastern University, Rutgers, Stanford University, University of California-Berkeley, University of California-Davis, University of California-Los Angeles, University of California-San Diego, University of Illinois at Chicago, University of Utah, and Washington State University-are participating in the CoLoS USA project. The development of interactive multimedia lessons is the cornerstone in realizing the CoLoS philosophy [4].
In this paper, we review the software and hardware components necessary for developing interactive multimedia lessons. Examples of developed multimedia software for electromagnetics, calculus, and physics will be described to illustrate the role of each of the development components in the overall quality of the educational multimedia module.
It is emphasized that, in spite of the fact that multimedia production requires extensive software and hardware resources, the major development components are readily available and affordable, and educators are encouraged to take advantage of these recent advances to develop highly successful educational modules.
Content is the foremost concern of any educational product, and computer tutorials are no exception. Not all topics are suitable for computer-based instruction, so care must be taken to select only those topics which benefit from the use of computers. Abstract and difficult to visualize concepts generally work well in tutorials where the visualization capabilities of the computer can be emphasized. Electromagnetic waves are an example of an abstract concept which students often have difficulty integrating into their intuition. The computer, however, can represent electromagnetic waves graphically, with distinct intensities and phase fronts. Futhermore, interaction of electromagnetic waves with materials, motion of charged particles in electric and magnetic fields, and explanations of the basic principles of radiation can be better explained and certainly better comprehended when presented in association with computer graphics. When developing multimedia tutorials, it is generally a good idea that instructors continually ask themselves if the advantage gained by computer-aided instruction is worth the development effort.
Though content is the basis on which tutorials should be judged, good presentation is vital to convey the content to the student. In a designing a multimedia tutorial, instructors have more latitude in presentation than they would in writing a textbook. The use of hyperlinks allows students to control the sequence of concepts presented. Interaction between the student and the computer can engage the student more fully and lead the student to an understanding of the ideas being covered rather than merely present the concepts. Finally, because multimedia tutorials present information through graphics, animations, video, and sound, educational multimedia modules may appeal to some students who find textbook learning rather difficult or boring.
The flexibility gained by presenting material in a multimedia tutorial comes at a price. To make full use of the computer's interactive possibilities requires a great deal of programming to accommodate a variety of student responses. Developing graphics, animations, video, and sound consumes a great deal of time, and these additions require huge amounts of computer storage space. Ultimately, this means that tutorials cannot exhaustively cover a subject and retain the features which distinguish them from textbooks. While developing the software, a balance between desirable flexibility and the available computer resources must be carefully considered. The CAEME center typically spends six person-months to develop each lesson which generally contain two to three hours of instruction.
Simulation software and multimedia assets are considered to be the building blocks of a multimedia software package. Simulation software provides students and faculty with the ability to simulate and solve a wide variety of problems and to emphasize practical applications of some of the concepts. Multimedia assets, on the other hand, enhance these simulations with video, sounds, and animated discussions. Multimedia assets include computer graphics, computer animations, digital videos, and digital sound. CAEME has developed an extensive database of multimedia assets including graphics and animations of physical phenomena, videos of laboratory demonstrations, and packages of simulation software [5-7]. In the development of a new lesson, these existing assets will be used when possible and new assets will be developed and added to the collection.
Subject to the fact that simulation software packages are available, which is the case in electromagnetics using Vol. I and Vol. II of the CAEME Software Book (see Appendices A and B for contents), the development of multimedia assets can be broken down into three general areas: (1) computer graphics production, (2) video production, and (3) sound production. In the following sections, each of these topics will be discussed in more detail.
The development of quality computer graphics is essential to presenting visual ideas clearly. Three-dimensional animated computer graphics are especially useful in simulating real situations in semi-immersive virtual reality. The computer graphics that will be developed for the lessons are either two-dimensional, three-dimensional, or three-dimensional with animation. For a given idea, the graphics format is chosen based on a tradeoff between the impact of the graphics versus the computer resources necessary to produce the image. All the graphic images developed by CAEME are produced by a graphic artist in cooperation with the curriculum specialist and technical staff.
Two-dimensional graphics development can consist of scanned images or computer-generated images. Scanned images will be captured from a photograph of the graphic idea with a suitable resolution scanner. Once images are scanned, Adobe Photoshop [8] may be used to correct any imperfections in the image. Computer-generated images are produced using an object-oriented application such as Macromedia Freehand [9] or Adobe Illustrator [10]. These images are then imported into Adobe Photoshop where modifications and/or special effects can be added.
Three-dimensional graphics development of still images involves a three-step process. First, the object is modeled in either an organic modeling environment or a mechanical modeling environment, depending on the desired shape or complexity of the object. The difference between the two modeling environments is that the former utilizes a spline mesh for optimal modeling of curved shapes and the latter utilizes a square mesh for optimal modeling of objects composed of polygons. Once the modeling environment is determined, the object is created in wireframe form.
The second step in three-dimensional graphics development is the texture mapping of the model. Each wireframe surface in the model is assigned a ``texture'' which is a picture of a surface. The modeling software used will wrap the texture around a complex object giving it the desired appearance of the surface. At this step of the process, surfaces that are transparent (glass) or translucent are identified and textured appropriately. Light sources are then used judiciously to create the desired shadows and the 3D model is rendered to create the desired image.
The final step in three-dimensional graphics development is the rendering of the image. In this part of the process, the computer calculates the light, texture map, and shadow of each pixel in the image based on the light sources in the model. There are two rendering schemes that are used to create the final images: phong shading and ray tracing. Phong shading can be used when a sharp, high-resolution image is not necessary. This type of rendering does not take into account obstacles between an area in the image and a light source, and consequently does not calculate shadows. Therefore, phong rendering is quick and is used when shadows are not necessary or to test the placement of objects in a model without performing a slower ray-trace rendering. Ray tracing is a complete rendering scheme that takes into account the rays of light on each pixel in the image coming from each light source. This rendering scheme also calculates reflections of light from objects.
Another possible rendering scheme is ray painting. This is a special-effect rendering scheme. Ray painting, for example, would be used to make an image appear to be oil-painted on a canvas or air-brushed onto a metal surface. This rendering scheme is only used if the special effect would add impact to the lesson under development.
Three-dimensional animation development is an expansion of 3D still graphic image development. In animation development, the 3D model is developed and textures are mapped and then the animation is defined. Defining an animation involves applying motion to an object or objects in the model, arranging the lighting, calculating the chronology of the animation or the required frame rate, placing the camera with the correct perspective, applying motion to the camera, and simplifying the model to enhance motion and focus attention. Special effects may also be applied to an animation such as object morphing, explosions, motion blur, and different levels of transparencies.
The CAEME Center has experimented with several different modeling and rendering packages to produce 3D images and animations. The Power Macintosh has been found to be a viable platform for the development of 3D images. Power Macintosh native versions of Strata Studio Pro [11] and InfiniD by Specular [12] are used to develop images for lessons.
Video production for use in a multimedia education environment is a multistep process. A video must first be made on tape which involves full-scale movie production. CAEME has been successful in producing quality video in-house. The most important issue that must be considered in producing a video for computer playback is the impact of the video versus the play time. Disk space is a limiting factor, so a video clip must make its point clearly in the shortest time possible. The movement of the subject and the camera is another important issue. A video for computer playback has a limited amount of data that can be updated to the computer screen; so to avoid choppy motion or skips, camera motion must be limited.
Once a movie has been recorded on video tape, the movie must be digitally captured to the computer. CAEME has successfully captured video using an Intel Indeo Video Capture/Compression board in a 486 66-MHz PC and the Microsoft Video for Windows software [13], Adobe Premiere [14], or the Macintosh Power PC 8100-AV and Quicktime. The number of frames per second captured is chosen based on the content of the movie, the disk space available for the movie, and the desired motion continuity. The size of the movie is also chosen based on these factors as well as logistics in the program itself. The frame rate and size have an inverse relationship, so a balance must be achieved. The frame rate is not absolute at this point because it can be changed during editing. However, it can only be reduced so it is advantageous to achieve the highest frame rate possible during the capture process.
The next step is editing the movie. Adobe Premiere is an excellent software tool for editing digital movies. In this step, portions of the raw video are cut and pasted to make the final product. Also, dissolves between video sequences are added and the sound is normalized. If any background sound is desired, it is also added. Any special effects that are desired will be performed during this part of the process.
The final procedure in the production of video is compression for CD-ROM playback. Adobe Premiere, Quicktime, Quicktime 2, and Microsoft Video for Windows are all equipped with compression algorithms. Some examples of often-used compression schemes are Microsoft Video 1, Intel Indeo r.3, Cinepak by Codec, and Quicktime. The compression scheme is chosen based on the platform on which the movie will be played as well as the desired quality of the movie versus the disk space required. For example, using one compression scheme may make a movie that requires relatively little disk space but is pixelated. Another compression scheme may produce a movie which has a high image quality but requires a relatively large amount of disk space. Once again, these tradeoffs must be considered in the context of the overall impact of the movie.
Multimedia sound assets include narration and sound effects. The sound production procedure for narration is to first write the score to be recorded. Next, a sound-proof area must be set up in which to record the narration. Using a good-quality computer microphone, the narration can be recorded directly to the computer hard drive. There are many software packages available to record sound with a computer. The CAEME Center has found Wave Studio by Creative Labs [15] in Windows and SoundEdit 16 [16] for Macintosh to be suitable for most needs.
Sound effects require either props brought into the recording area or remote recording devices taken to the sound. If a recording device is used such as a DAT tape recorder, the sound is sampled quite easily by one of the previously mentioned software packages.
Once a sound has been recorded to the computer hard drive, the sound can be edited. Editing options include mixing the sound with other sounds, changing pitch, adjusting volume, removing unwanted noise or silence, or applying special effects such as reverb, echo, and reverse play.
Once a multimedia asset has been developed, the next step in the procedure is to prepare that asset for the platform on which it will be used. Graphics file formats, animation file formats, and video file formats vary from one software package to another, not to mention from one computer platform to another. The CAEME Center uses several software tools to convert file formats including DeBabelizer [17] and Graphics Workshop [18] for image files, Adobe Premiere and Autodesk Animator Pro [19] for movies and animations, and Blaster Master [20] for sound files.
The issues to consider regarding file format conversion are changes in performance, quality, data transfer size, and disk space usage. For example, the size a given image file occupies on the disk can vary by a factor of 10 based only on the image format in which the file is written. Therefore file format conversion is not just a question of getting a given file into a format that the end product will accept, but it is also a question of what is the best available and allowed format for a given file.
Multimedia asset development and file format conversion provide the pieces with which to build the multimedia modules. However, these pieces alone are not sufficient for teaching a subject. In the next step, these multimedia assets are combined with other information and assembled into a coherent program that will become a multimedia lesson.
An authoring system is an environment in which to create a multimedia lesson in a timely and cost-efficient manner. The CAEME Center uses Macromedia's Authorware[21] with support from Macromedia's Director[22] and Novell's AppWare[23]. These authoring environments provides tools to develop user interactions, enter text, perform limited animation in two dimensions, evaluate user input, and integrate multimedia assets such as sound, animations, and graphics.
Authorware has generally been the package of choice for educational applications because of the ease in which these applications can be constructed. Macromedia's Director allows a programmer more control over the program, but at the cost of greater development time. Novell's AppWare is the most difficult of these packages to learn, but offers the greatest control to the programmer. AppWare can be described as a graphical programming language where you construct a program by connecting objects and functions. AppWare was designed to build applications for Novell's NetWare, and as such does not have a great deal of support for multimedia. But for programming problems it is both easier to use and more portable than high level languages like C or FORTRAN. Table 1 provides a brief comparison between Authorware, Director, and AppWare.
Macromedia's Authorware and Director are definitely the most widely used authoring packages. But there are a number of other packages available, and educators are encouraged to look into the capabilities of other authoring systems. Quest 5.0 [24] for Windows, for example, seems to have some very attractive features such as its built in script language based on C. However, this products does not provide cross-platform support.
During authoring, developers follow the lesson plan previously written on paper to create the tutorial. At this point, the developer has the lesson plan and the multimedia assets in the correct format for integration into the lesson. With this preparation, the task of building a lesson is reduced to entering text, performing simple animations, and defining interactions and user input. If any of the Center's collection of simulation software is to be used in the lesson, the software is also linked to the lesson and the appropriate help screens are prepared and added.
