A Novel Human Computer Interaction Paradigm for Volume Visualization in Projection-Based Virtual Environments

Abstract

We propose a novel Human Computer Interaction (HCI) paradigm for volume visualization in projection-based immersive virtual environments (VEs). This paradigm is intuitive, highly efficient and allows accurate control over the virtual objects. A fine control mode for direct manipulation is proposed to address the low accuracy problem of virtual object manipulation in VEs. An agent object interaction method is proposed to provide more flexibility in manipulating the volume objects. A two-handed scaling method is proposed to conveniently scale the volume object along one, two, or three axes. Finally, a ghost object paradigm is proposed to address the motion constraint problem for virtual objects. An implementation using a 3-state tracked glove setup as the input interface is discussed. How basic functionality for volume visualization can be transferred from the 2D WIMP (Window, Icon, Menu, and Pointer) interface to a 3D VR interface is also systematically discussed.

Characterization of multiphase flows integrating X-ray imaging and virtual reality

“…The depth cues provided to the viewer are extremely important for their understanding of the three-dimensional structures they are viewing (Zhang et al, 2001). Because volumetric data is traditionally viewed from the outside in, the simplest method of changing the viewpoint is for the user to physically move around the volume (He et al, 2007). This is a natural interaction and helps increase both immersion and understanding (Haubner et al, 1997).…”

“…One method that has been proposed for applying clipping planes is to track the user's hands. When the user wants to add a clipping plane, the user can simply draw the clipping planes needed to eliminate unwanted geometry (He et al, 2007). While this method is intuitive, it requires the location of the desired clipping plane to be within the physical reach of the user.…”

“…However, transfer functions are extremely challenging to implement in VR because they require precise values to be set and, despite decades of research into image processing, the most prevalent way of defining a transfer function remains trial and error (Pfister et al, 2001). In previous work, transfer functions have been adjusted using onscreen menus (He et al, 2007). While this is effective when a limited number of predefined transfer functions are available, if a new transfer function is desired, it would be a tedious task to create one using just a 3D menu.…”

“…He et al (He et al, 2007) identified four basic interaction tasks required for volume visualization in virtual reality: Each of these five tasks will be considering in the following sections.…”

“…Volumetric measurements are commonly found in medical imaging in the form of MRI and CT scans. There have been many attempts to visualize these data in virtual reality, which provides a good foundation for the work herein (Haubner et al, 1997;He et al, 2007;Noon, 2012). However, it should be noted that there is one key difference between medical volumes and fluid flow volumes.…”