Multi-monitor 3D model visualization

Twenty five years ago, brand new PCs were usually delivered with tiny 14-inch monitors. Nowadays, 17 inch is a minimum, and generally new PCs come with 19, 21, 24 inch monitors - or even more - and often in a panoramic format. Using a large monitor, users can see more and be more efficient (naturally this is true up to a certain point, and as long as there is enough room on one's desk...). Many graphics cards can accommodate more than one monitor. That is quite handy, as one can use two monitors simultaneously in an « extended desktop » mode. The 2 monitors then behave as a single larger monitor, with the exception that the user has to live with a seam in the middle of his desktop.

CAD visualization can take advantage of wider monitors. For instance, a larger monitor may be used to display larger views, something useful for the visualization of large models. However, in the specific case of 3D model visualization, the use of multiple monitors has a major advantage over a single panoramic monitor - and the idea comes from the world of computer games.  When multiple monitors are used in combination, they are usually positioned one next to each other, roughly on the same plane (see Fig 1A). Such a configuration makes a lot of sense, as the monitors are used in combination to represent the desktop, which is a 2D surface. However, individual monitors can also be positioned at an angle (see Fig 1B) - something that cannot be done using a single large monitor.

 

Figure 1: Two monitor placement configurations

Why is that angle configuration interesting? Let's consider a single standard monitor used to visualize a 3D city model (see figure 2). The monitor provides a standard view of the buildings. By using a larger monitor, one can get a wider view (figure 3). That is nice, but there is better.

 

Figure 2: Standard monitor model view

 

Figure 3: Panoramic monitor model view

Let's now consider a configuration in which 3 monitors are used (as in figure 1B). Instead of placing them along the same plane to create a larger monitor (as in figure 1A), they are installed to fill most of the field of view of the user. Each monitor is used to display an individual MicroStation view. Each view is rendered by its own MicroStation camera - all 3 cameras are located at the same location inside the model, but are all looking in different directions (figure 4). They are actually oriented the same way as the monitors. As a resuilt, the user would see the model the same way as if he was inside it.  By looking to the left, he would see the part of the model located to his left, or to the right if he turned in the opposite direction (see figure 5).

 

Figure 4: Multi-camera configuration

 

Figure 5: Multi-view model visualization

The idea seemed nice in theory - so we tried it. We plugged 3 monitors to a single PC (using a Matrox TripleHead2Go) and implemented a prototype that synchronizes 3 MicroStation views, each one managed by an individual camera (see figure 6). The user controls the view in the central monitor, and the left and right views are automatically updated. Our results are convincing: the system does indeed increase the feeling of being inside the model. The refresh of the views is slower though, as MicroStation has to update 3 views instead of one for each user view operation. The technique turns out to be useful for large models that the user can explore by walking or flying - which is the case of virtual city models, as the one shown in figure 6. By providing a wider field of view, the system helps the user getting a view of the model that is closer to reality, enhancing the feeling of presence, helping him navigate more efficiently and getting a better understanding of the 3D structure, size and shape of the model. It helps getting more out of standard monitors.

 

Figure 6: Our multi-monitor setup

 

Computer gamers have been using that technique for a while - adding more monitors, installed at an angle, can significantly increase the feeling of being immersed in a game. That technique applied to CAD is a tiny step that, combined with other techniques such as 3D stereo visualization, may eventually bring us closer to true virtual reality model visualization, as shown in Bruce Branit's vision "Word Builder" (see my other blog post entitled: "From Dream to (virtual) Reality".

Want to see more?  Watch the full seminar at: Enhanced Model Visualization and Remote Collaboration

Anonymous
  • Hi Bigean,

    very interesting indeed.  I was not aware of that product - thanks for pointing it out.  

    We actually experimented with the head tracking technique last year - check my seminar at: http://connected.bentley.com/viewSeminars.aspx?BEC_SS_ID=260 and you will see our demo.  However, our prototype was based on the use of a webcam, combined with image-based head tracking software.  It was far from being as smooth and fast than TrackIR though.  In the demo shown in the seminar, we combined head tracking with our 3D stereo monitor.   If you are interested in seeing it, please come and see us at the BE conference in May - we will be pleased to let you try it!

    As you pointed out, head tracking would also have potential for multi-monitor display.  We would have to program it differently than what they do in the TrackIR demo though - In their system, Yaw head movement is interpreted as yaw camera movement - this is to let the user get a wider field of view.  That feature would become less attractive in a multi-monitor display system, as the monitors are used for that very purpose (ie increasing the user's field of view).  That would deserve some thought - as there is certainly some potential.

    Thanks for your comment!

    Stéphane

  • Hi Stephane,

    nice article. The key is to couple 3 cameras moving simultaneously. I wouldn't have thought that's possible.

    Next step: Try "TrackIR". I'm using this in a specific game and that's another dimension in immersion. What does it do? A webcam-like device tracks your head movements and translates that into virtual camera control in 3D software. So if you turn your head slightly to the left, the scene turns accordingly.

    Maybe you're able to couple that to MicroStation and 3 mon's ... have fun!!!

    Look for hardware details on naturalpoint.com/trackir/

    Bigean