Authors: Xiaohong Gao, Mustafa Hassan
Morphing, or metamorphosis, is widely applied in the fields of computer games and entertainment in order to achieve drastic special effects by the application of producing a sequence of animated motion transforming objects from one to another gradually. Because of its capability in manipulation of shapes, morphing technique has also been employed in modelling of geometric objects, especially in three dimensions (3D). To morph and visualise a 3D object, a cloud of points have to be connected into meshes in an effort to achieve a realistic view, which however also poses a substantial challenge. On the other hand, another difficulty to circumvent is to define a path for morphing interpolation, which varies with the characteristics of an object to model. In this study, mesh morphing techniques have been investigated in the hope to model the process of brain tumours growth and shrinking. To do this, two volumes of a tumour from MR images, acquired prior to and after key-hole surgery of tumour removal respectively, are segmented first using levelset deformable models. Then these two shapes are morphed into a middle object, a sphere, in order to find corresponding points, which is followed by the approach of Marching Cubes to form the meshes/surfaces of these objects. To define a path for interpolation, the model of physical balloons is created first by the application of two webcams that are employed to monitor the deflating process of the balloons when the air is let out gradually, facilitating the route allowing the interpolation of morphing path. Preliminary results show a reasonable match between balloons and tumours and morphing techniques are well suited to model the procedure of tumour deflation through a key-hole surgery, leading to the bespoke real-time visualization of object deformations.