the largest being Common Intermediate Format (CIF), which has an aspect ratio of 352 x 288 pixels. The previous remote visualization system therefore utilized a complex system of four single CIF streams for each eye perspective, resulting in a static aspect ratio of 4x Common Intermediate Format (4CIF) (704 x 576 pixels) and 8 streams [108].
CoWebViz allows to use a single stream, in contrast to the previous four streams, with an ar-bitrary choice of the aspect ratio. This allowed for a much easier handling and, thus, simpler client system. This can for instance be seen in the differentiation between the destinations during the first class sessions, where it was easily possible to send a specific higher aspect ratio to the Chicago classroom and a lower to the Cardiff classroom. But still, our collaborators empirical opinion at Cardiff was that the CoWebViz usage resulted in a better overall visualization quality in terms of compression artifacts and colorization. [265]
The usability of the base visualization application’s remote usage via CoWebViz is on principle equal to its direct local usage. An obvious difference of both remote applications (CoWebViz and previous system) is the slightly slower performance, because there always is a noticeable lag between the finished rendering on the server side and its presentation on the remote client. But whereas the previous remote system was only able to exactly stream the two stereoscopic streams to the client, CoWebViz also allowed for other usage patterns. Previously, both stereoscopic streams needed to be loaded on the computer that was responsible for the stereoscopic projection.
The lecturer, however, required to sit in front of the class with a separate computer to control the 2D and 3D visualization. It was therefore required to connect the lecturer’s computer via a VNC connection to the computer of the stereoscopic setup in order to control the stereoscopic visualization.
CoWebViz in contrast simply allowed to open a specific control view (see Figure 6.3c) that shows no visualization but allows to fully control the visualization without further deployment.
6.2 Other applications of CoWebViz
The previous section describes the utilization of CoWebViz 0.1 on a two-projector stereoscopic system. The optimized CoWebViz 0.2 was developed und used for other scenarios and stereoscopic setups, which are described in this section. Whereas, each of these stereoscopic content types can be used solely, they can also be used simultaneously in a single collaborative session as enabled by the parallel architecture (see Section 5.1) and illustrated in Figure 6.4.
6.2.1 Anatomical education in medical school
CoWebViz was used to teach anatomy to medical students at The University of Chicago’s Pritzker School of Medicine in August/September 2011. The class was conceptualized as an optional session additional to the standard medical anatomy class. The visualization was presented on a
(a)Client instance: stereoscopic left eye view. (b)Client instance: stereoscopic right eye view.
(c)Client instance: control view.
Figure 6.3. CoWebViz’s distinct client instances (web pages) as used in the classroom. Each can be used to control the visualization, but the control view is dedicated to this functionality.
stereoscopic two-projector system, which required two CoWebViz client instances (one for each view). Teaching assistants held the class and controlled the visualization via a CoWebViz control client instance (see Fig. 6.3c) on a Laptop. They did not have any experience with this setup before the class started. We therefore developed several additions in order to help them using it: the client side GUI controls and the visualization scripting, both described in Section 5.6.
Whereas the scripting was not used, the GUI was supportive for an instantaneous system usage.
But since they used the system the first time in class, they quickly switched to take our direct personal support with the keyboard based control. The class was only realized for two sessions.
This class was based on the same setup as the previously described anatomy class for biology students (Section 6.1), but had no second participating remote group.
6.2 Other applications of CoWebViz
Figure 6.4. Stereoscopic visualization types for a sole or simultaneous usage as provided by CoWebViz (based on [51]).
The usage of the optimized CoWebViz version 0.2 in this class showed the advantages of the revised design in a practical setting. The main observations where that the inter view lag (lag be-tween the presentation of the left and right view) was not recognizable anymore. The system was also usable without specific server side configurations, but delivered a fluent usable visualization during modification phases and maximum quality when viewing.
6.2.2 Demonstration in conference rooms
CoWebViz was and is occasionally used to present stereoscopic visualization for various reasons to current or potential future collaborators. The visualization was presented on state of the art 3DTVs at two locations, The University of Chicago Hospital and the NorthShore Univer-sity HealthSystem Research Institute. These sessions usually required several client instances of CoWebViz, one for the 3DTV and others to control it on a Laptop. Such TVs are much eas-ier deployable than two-projector setups. It was therefore also possible for a colleague to use CoWebViz instantaneously on his private 3DTV.
The technical environment was in principle and apart from the stereoscopic presentation identical to the class setup. Due to its simplified system architecture, few effort was necessary to extend CoWebViz to support a stereoscopic content type that is supported by 3DTVs (see Section 5.5).
The visualization was rendered by MedVolViz either on a visualization cluster at The University of Chicago or a high performing single computer at NorthShore University HealthSystem.
The usage in conference rooms was CoWebViz’s first usage on 3DTVs and therefore showed its feasibility.
6.2.3 Informing surgeons in the operating room
In 2013, CoWebViz was used in a pilot study3 to present stereoscopic visualization to a plastic surgeon during reconstructive surgery in the operating room, e.g. for craniofacial and free-flap breast reconstruction. While the diagnosis is raised on other systems, this stereoscopic presen-tation is an additional resource for a fast real-time guidance for the surgeon. The visualization of the patient specific imaging data is presented in stereoscopy on a 3DTV, which was specially deployed in the operating room. The system is currently not controlled by the surgeon, who is too much involved into the procedure, but by another person on his command.
A single CoWebViz client instance is used on a Laptop that is connected to the 3DTV. The visu-alization is remotely rendered on a high-performing computer at NorthShore University Health-System by MedVolViz. The distance to the operating room is about 20km.
Since this is an ongoing study, the results will follow. However, the current state of the study already shows that real-time visualization via CoWebViz is usable in the operating room of a single health corporation’s hospital with the visualization being rendered in a remote located data center.
6.2.4 Monoscopic ad-hoc collaborative usage
CoWebViz was used a single time for a truly unscheduled collaborative ad-hoc demonstration. It was used to present MedVolViz’s visualization and CoWebViz to collaborators at The University of Chicago with the visualization being rendered at the University of Chicago, but us being at NorthShore University HealthSystem. The demand for this session arose during a telephone conference. It was basically done during the phone call by starting CoWebViz and sending the URL to the collaborators via email. Both participants loaded the URL and modified as needed after oral communication.