Sehat Ullah

Haptic guides in cooperative virtual environments: Design and human performance evaluation

In this paper we simulate the use of two string based parallel robots in cooperative manipulation task. Two users standing in front of a large screen operate each robot. We propose two haptic guide models, and investigate their effects on cooperation, co-presence and users performance. In addition we also examine the effect of object-based force feedback in cooperative work. Ten volunteer subjects had to cooperatively perform a peg-in-hole task. Results revealed that haptic guides have a significant effect on task execution. They not only increase users performance but also enhance the sense of co-presence and awareness. Our investigations will help in the development of VR systems for cooperative assembly, surgical training and rehabilitation.

Factors affecting the design and tracking of ARToolKit markers

The quality of ARToolKit markers plays a vital role in the performance of Augmented Reality applications, but currently there is no algorithm or quantitative measure to guide users for designing high quality markers and their reliable tracking. This paper presents eleven factors that are important for designing and tracking ARToolKit markers. The effect of each factor on the quality (accuracy, detection speed, and inter-marker confusion) of marker tracking system is investigated and the optimal value(s) of these factors are found. Using the optimal values of these factors one can achieve the goal of reliable and robust tracking of fiducial markers.

Indoor vision-based auditory assistance for blind people in semi controlled environments

This paper presents an indoor auditory navigation system for blind and visually impaired people using computer vision based approach. In our approach, fiducial markers augmented with audio information are placed in the environment. The blind user holds a webcam attached to the system in his/her hand and navigates through the environment. The audio assistance is provided to the user whenever a particular marker is detected by the camera and thus enables him/her to independently navigate in the environment. The proposed navigation system provides two types of guidance (1) free mode guidance (2) targeted mode guidance. In the free mode guidance, the user navigates freely in the prepared environment and the system informs him/her about his/her current position through the audio information about the surrounding based on the detected marker. In the targeted mode guidance the user is guided from a source (current) position to his/her desired destination in the environment through the shortest path. Five blind users evaluated the system (both modes) in a semi controlled environment. The results obtained from the experiments indicate that the proposed system is successful in assisting blind users inside a huge and complex building. In addition the solution is low cost and gives high accuracy rate.

The Effect of Multimodal Virtual Chemistry Laboratory on Students’ Learning Improvement

This paper presents a novel Multimodal Virtual laboratory (MMVL) for the learning of chemistry experiments. MMVL is a Virtual Reality environment where the user can perform chemistry experiments like a real world chemistry lab. The user can easily interact with MMVL through 3D interaction interface. The audio and visual information about each chemical objects are provided to its users. The system improves the learning capabilities of students in chemistry education. The analysis shows that the average learning of untrained student is 32.7% while that of trained students increased to 83.5%. Experiments reveal that confidence level in practical field of students who got training in MMVL is much better than those who did not use it.

Measuring the Student’s Success Rate Using a Constraint Based Multi-modal Virtual Assembly Environment

Personnel Training is considered as the most important prerequisite in the assembly operations of any kind of equipment/apparatus ranging from simple nut-bolt assembly to complex equipment (e.g., aircraft engine) assembly. This paper presents a novel Virtual Reality Training System (VRTS) for the constraint based assembly of a 3phase step down transformer. The ARToolKit [1] markers are used for interaction with the VRTS. The system improves the technical skills of students in the real assembly environment. The analysis shows that the average success rate of untrained students is 35.7% while that of trained students increased to 81.5%.

The Effect of Learning-Based Adaptivity on Students’ Performance in 3D-Virtual Learning Environments

Research demonstrates that individualized instruction is superior to the traditional one-size-fits-all teaching approach. The use of 3D virtual environments for educational purposes is becoming attractive because of their rich presentation, user friendly interaction techniques, and adaptive capabilities. However, defining the adaptive aspect of 3D virtual learning environments (3D-VLEs) is a challenging task. In this paper, we quantitatively measure learning skill of a student through a fuzzy logic-based approach and use it as adaptation criterion for changing the contents of 3D-VLEs. The system displays customize teaching materials for different students, which results in improved learning. The experimental results show that the proposed approach is effective and can be efficiently used to enhance the learning capabilities of students in 3D-VLEs.

Multi-Layered Hierarchical Bounding Box based interaction in virtual environments

Interaction techniques play a vital role in the success and effectiveness of a virtual environment. Therefore, researchers have put much effort on the design and development of easy, realistic and intuitive interaction techniques. In this paper we present a new interaction technique specifically designed for educational environments. The technique uses a step by step and hierarchical approach to have information rich, selection/manipulation and exploration of an object and its constituent parts (objects). The technique is implemented and evaluated in a virtual environment having a human skeleton designed in 3DS max. Subjective evaluation reveals that the technique is very useful and suitable for educational virtual environments.

The applications of marker-based tracking in semi-controlled environment

Tracking the environment is the key challenge for the development of Augmented Reality (AR) applications. Marker-based tracking is most widely used technique in AR applications. This technique provides accurate, fast and robust tracking in controlled environments. On the other hand its performance degrades in semi-controlled environments due to lighting condition variation. To overcome these challenges and enhance the usability of marker-based tracking to semi-controlled environments, the concept of multiple pattern files is proposed. Multiple patterns of one marker are captured during different lighting conditions and kept in database for tracking. The proposed technique improves the marker tracking accuracy under varying brightness and contrast values. The method is compared with conventional technique of single pattern file by developing an augmented reality navigation system inside a complex building. The accuracy of conventional method is 77.36% that is increased to 95.27% by using the proposed technique.

Optimality of black to white ratio and information complexity for robust marker recognition

Fiducial markers are widely used in many Augmented Reality (AR) applications such as to manipulate AR objects, robot navigation, education and AR based games. ARToolKit is an open source, easy to configure and well-documented tracking system which is widely used for designing marker based AR applications. The quality of ARToolKit markers plays a vital role in the performance of these AR applications, but currently there is no algorithm nor quantitative measure to guide users for designing high quality markers in order to achieve reliable tracking. In this paper we experimentally analyze the effect of the two markers design attributes, including black to white ratio (B/W) and information complexity on marker recognition. Based on above analysis, we developed threshold based algorithms for optimizing the two attributes. These algorithms also provide various cognitive aids and helps to the users. The work done will help ARToolKit users to design high quality markers with little efforts and as a result will increase the efficiency and performance of their AR applications.

3D Model Visualization and Interaction Using a Cubic Fiducial Marker

Fiducial markers are generally used for tracking the camera position and orientation in augmented reality applications. The tracking performance of existing markers degrades due to marker occlusion. Similarly it does not support 3600 rotation in all axes and consequently it becomes difficult to achieve realistic/intuitive manipulation & visualization of virtual objects/contents. This paper presents the applications of a cubic marker in 3D models visualization and interaction and overcomes the above challenges. A cube having six fiducial markers, each on its face is used to be tracked from a single camera. The corners of the cubic marker are used to find its center. A 3D model is visualized on the center point of the real cubic maker. This cubic marker produces robust tracking results during occlusion. The visualization of 3D virtual models and interaction with these models are more realistic and ergonomic using the cubic marker.