Inexpensive solution for real-time video and image stitching

Image stitching is the process of joining several images to obtain a bigger view of a scene. It is used, for example, in tourism to transmit to the viewer the sensation of being in another place. I am presenting an inexpensive solution for automatic real time video and image stitching with two web cameras as the video/image sources. The proposed solution relies on the usage of several markers in the scene as reference points for the stitching algorithm. The implemented algorithm is divided in four main steps, the marker detection, camera pose determination (in reference to the markers), video/image size and 3d transformation, and image translation. Wii remote controllers are used to support several steps in the process. The built‐in IR camera provides clean marker detection, which facilitates the camera pose determination. The only restriction in the algorithm is that markers have to be in the field of view when capturing the scene. Several tests where made to evaluate the final algorithm. The algorithm is able to perform video stitching with a frame rate between 8 and 13 fps. The joining of the two videos/images is good with minor misalignments in objects at the same depth of the marker,misalignments in the background and foreground are bigger. The capture process is simple enough so anyone can perform a stitching with a very short explanation. Although real‐time video stitching can be achieved by this affordable approach, there are few shortcomings in current version. For example, contrast inconsistency along the stitching line could be reduced by applying a color correction algorithm to every source videos. In addition, the misalignments in stitched images due to camera lens distortion could be eased by optical correction algorithm. The work was developed in Apple’s Quartz Composer, a visual programming environment. A library of extended functions was developed using Xcode tools also from Apple.

Remote presence: supporting deictic gestures through a handheld multi-touch device

This thesis argues on the possibility of supporting deictic gestures through handheld multi-touch devices in remote presentation scenarios. In [1], Clark distinguishes indicative techniques of placing-for and directing-to, where placing-for refers to placing a referent into the addressee’s attention, and directing-to refers to directing the addressee’s attention towards a referent. Keynote, PowerPoint, FuzeMeeting and others support placing-for efficiently with slide transitions, and animations, but support limited to none directing-to. The traditional “pointing feature” present in some presentation tools comes as a virtual laser pointer or mouse cursor. [12, 13] have shown that the mouse cursor and laser pointer offer very little informational expressiveness and do not do justice to human communicative gestures. In this project, a prototype application was implemented for the iPad in order to explore, develop, and test the concept of pointing in remote presentations. The prototype offers visualizing and navigating the slides as well as “pointing” and zooming. To further investigate the problem and possible solutions, a theoretical framework was designed representing the relationships between the presenter’s intention and gesture and the resulting visual effect (cursor) that enables the audience members to interpret the meaning of the effect and the presenter’s intention. Two studies were performed to investigate people’s appreciation of different ways of presenting remotely. An initial qualitative study was performed at The Hague, followed by an online quantitative user experiment. The results indicate that subjects found pointing to be helpful in understanding and concentrating, while the detached video feed of the presenter was considered to be distracting. The positive qualities of having the video feed were the emotion and social presence that it adds to the presentations. For a number of subjects, pointing displayed some of the same social and personal qualities [2] that video affords, while less intensified. The combination of pointing and video proved to be successful with 10-out-of-19 subjects scoring it the highest while pointing example came at a close 8-out-of-19. Video was the least preferred with only one subject preferring it. We suggest that the research performed here could provide a basis for future research and possibly be applied in a variety of distributed collaborative settings.