This project focuses on the techniques of probing, deforming and cutting three dimensional volumetric objects for a virtual dentist training simulator. Using a haptic (force) feedback device the sense of touch can be incorporated enabling the user to feel the resistance of cutting or drilling through virtual objects. The techniques will be applied to a Virtual Dentist Training Simulator.
Most current virtual simulations for training involve probing the virtual environment with either a single point or a rigid object. The process of determining a force based on the position and orientation of the haptic device is known as haptic rendering. Haptic feedback has been used in conjunction with three-dimensional objects representing virtual tools in a number of applications ranging from surgery to assembly tasks. However, the contact points between the tool and the scene are often restricted to a set of points strategically placed on the surface of the tool. An example of this technique is the VOXMAP-Pointshell approach. Laycock and Day have proposed a new approach to allow any contact point to be obtained between the tool and the objects in the scene. Developing simulations with rigid tools induces a large overhead when determining accurate reaction forces particularly when there are multiple points of contact. For certain applications the flexibility of tools should also be considered and so these simulated rigid tools are too constrained. The advantage of simulating tools in software is that they can be applied to a wider variety of applications in conjunction with smaller portable haptic devices.
This video illustrates a rigid drill interacting with three dimensional volume data representing a tooth.
In Endodontic procedures simulating deformable tools with volumetric models which permit deformations, drilling and cutting of material is vital for a virtual training simulator. Root Canal Surgery is one application where the deformation of the tool is fundamental to a successful operation. Achieving the correct visual and haptic cues during these simulated procedures is the main focus of this research. Virtual sculpting and carving simulations have been produced which are usually limited to single point interactions or more recently rigid tools. SensAble's Freeform modelling package is a good example of a virtual sculpting tool used in the design industry. In Endodontic procedures the rigid and deformable instruments are required to interact with a three dimensional model of the tooth constructed from several materials each exhibiting different properties.
Yu Liu, Dr. S.D. Laycock, Prof. A.M. Day.