Augmented Reality (AR) is part of the growing research area of Virtual Reality (VR). The term VR, defined as “a computer generated, interactive, three-dimensional environment in which a person is immersed” (Steve Aukstakalnis, David Blatner, Stephen P. Roth , 1992). As the field of research is growing, it is important for the researchers to enhance learning and data gathering from the environment and provide new ways to obtain knowledge. One way of achieving this is through the usage of Augmented Reality. The augmented reality system generates combinations of view for the user. In simpler definition, it is actually a combination of the real environment and virtual objects, generated to produce a combined output to the viewer. AR enhances the person's perception of the world.
Augmented Reality in medical training
AR has been used in entertainment, military training, medical, engineering design, robotics and tele-robotics, manufacturing and consumer designs for many years prior to its introduction. Fotis Liarokapis, Panos Petridis, Paul Lister and Martin White (2002) have developed “an interactive e-learning AR environ-ment” called Multimedia Augmented Reality Interface for E-Learning (MARIE) in which users can view and interact with 3D virtual objects aided by online instructors. This system uses the head-mounted display, camera, and computer for visual augmented reality to present 3D multimedia information to the learner regardless of gender or age group.
The usage of AR in medical field increases the efficiency especially in the students training area as there is no more the need to make use of real human or animal body to do analysis and surgery trial (Wenzel D., 2004). The same 3D object can be used to train a number of students instead of using one human body to train a group of students. In addition, AR enables students to learn more and become skilled in the surgery as the 3D image can be recreated and the surgery can be repeated whenever errors are made (Fuhrmann, 2001). AR is capable of creating end result of any actions taken in an artificial body similar to a real body. Students and trainee surgeons get the opportunity to learn from the consequences of each of their actions during surgery through AR.
While virtual reality is being widely explored by the computer scientists, Augmented Reality that improves the human vision and perception is becoming the focus of many researchers around the world. While virtual reality is computer generation of immersible environments based on real world, Augmented Reality is integration of graphics, text, sound, images and force feedback with real environment. Augmented reality can be the next wave that will revolutionise teaching and learning through real time interaction. This article discusses the use of AR to augment teaching and learning in classroom by presenting a simple and cost effective AR setup that merges real scenes with virtual scene or objects.
A topic on recreation of dinosaurs using DNA extracted from amber was selected to this experimental study. Storyboard was created to depict the sequence of extraction of DNA, injection into an egg and recreation of dinosaurs. 3D models were created to be merged with scenes inside classroom for interaction purposes based on the storyboard.
Virtual objects were developed
in the format of 3D using 3DS Max software. The created 3D models of dinosaurs were converted to VRML format. In order for the AR software to recognise the model, a marker was assigned to each model. Each marker had a pattern, which was unique to distinguish the recognition of virtual objects assigned to them. Markers were assigned to the models using the AR software.
The setup has three steps as explained below.
Setup digital video camera and calibrate.
The digital video camera is setup in front of the classroom. The equipment had to be set in front of the classroom in order to connect the laptop to the projector, which is already mounted in front.
Place the marker in the desired environment.
The AR markers were placed in at a location where camera is calibrated to recognise the markers to merge virtual models to augment.
Capture real scene and merge with virtual image.
Markers were placed in different locations of the classroom where the digital camera can be moved to capture the scene and the marker. AR software merged the real scene with virtual objects, which are the 3D models of dinosaurs to form augmented scene which is displayed in the monitor.This is projected on to the screen for the audience in the classroom to view.
This type of AR setting was chosen, as it is cost effective compared to using the head-mounted devices. A video camera was setup to capture the real world scenario. The video camera relayed the real environment captured. It passed through the graphics system using a Firewire card and an IEEE 394 cable connected to the video camera. Alternatively, if there is no Firewire card available, a video-capture card with attached Firewire port is also usable. The scenes were merged using AR Toolkit. A few different versions of AR software were used for these experiments. The augmented result was then projected as the output on the screen.
20 students who attended this experimental study were very excited to see the real time augmented scenes in the classroom. They interacted with markers by moving them to different location within the camera view where the virtual models were recognised. In this case, a projector is connected up from the laptop and the whole class gets to view what is displayed. However, the following limitations were found while using this setup in the classroom.
Low latency is the image registration error caused by system delays. The low latency problem can be solved by predicting the future motion or through careful system design (Azuma et al, 2001). However, this requires a thorough knowledge of the application domain to be incorporated as part of the AR system. In this case the topic for teaching selected must be analysed to create models, which are appropriate to be used with fixed AR setting. This careful planning and designing of the virtual models with the consideration of the real scenes in perspective will provide effective and enhanced learning environment for the students.
Limitation in the degree of movement and interaction
Tracking using markers and fixed camera method is currently limited in providing the degree of freedom of movement to the instructor. Camera has to be moved every time the markers are moved in order to be recognised to display the virtual models. The camera needs to be calibrated to recognise the markers when the markers are moved. Good results were obtained when the markers were fixed on the wall with fixed camera position. However, when the students want to hold the markers to interact, they had to hold the markers still in order to be captured and recognised to generate augmented scene. One way to solve the above problem might be developing teaching material that caters for fixed markers and camera in the classroom.
The virtual models developed as part of Augmented Reality can be used to train students to interact with virtual objects and real scene that allow them to visualise and understand certain topics in the subject taught in classroom better
In conclusion, the AR setup proposed for classroom in this article is feasible, cost effective, easy to setup and maintain. The virtual models developed can be used to train students to interact with virtual objects and real scene that allow them to visualise and understand certain topics in the subject taught in classroom better.
However, registration of virtual object with real scene is one of the major challenges when a student wants to interact by moving the markers in the classroom. Camera is unable to capture the marker accurately when the marker is moved or the camera is moved. This caused the recalibration of the camera, which made the recognition of the marker to be slow and time consuming. The interaction with virtual models and real scene is limited due to fixed markers and fixed camera position. The image needs to be fixed to still surface in order to get good results. Planning and designing of the teaching material that can take advantage of fixed camera and marker position may solve the problem.
Future work will focus on refined techniques and development of teaching material that can be tested with this AR setup and measurement of the outcome of learning using Augmented Reality.
Fotis Liarokapis, Panos Petridis, Paul Lister, Martin White (2002), “Multimedia Augmented Reality Interface for E-Learning (MARIE)”, World Transactions on Engineering and Technology Education 2002 UICEE Vol.1, No.2,173
Wenzel, D., (2004), “Augmented reality in Medical application”, http://www.fabuloz5.de/dirk/avr. pdf#search='augmented%20reality%20in%20 medical%20field'.
Fuhrmann, A. L., (2001), “Virtual reality in medical application”, http://www.bmvit.gv.at/sixcms_upload/media/223/virtual_reality_in_ medical_applications.pdf#search='augmented%20r eality%20in%20medical%20field', Date referred 26 May 2005.