Interactive Volume Visualization and Editing Methods for Surgical Applications

Volumetric imaging modalities are increasingly being used in surgical applications. However, visualizing the 3D information contained in these datasets effectively on a 2D display is a challenging problem. Most important issues to overcome are the occlusion of different anatomical features of each other and the difficulty of visualizing the depth information of a given pixel in a 2D image. Moreover, the resulting image is aimed to be used to guide actions performed on the patient, therefore the mental registration of real and virtual spaces has to be considered when designing visualization and interaction approaches.;This work proposes an interactive focus + context visualization method that uses the Magic Lens interaction scheme to select important parts of volumetric datasets while displaying the rest of the dataset to provide context for the mental registration process. The Magic Lens paradigm is extended to handle arbitrarily shaped selection volumes, enabling interactive volume editing to visualize different anatomical structures from multiple datasets in a single coherent view. Capabilities of modern graphics hardware are used to achieve real time frame rates. The implementation of these methods introduces novel technical contributions to view and to select arbitrarily shaped sub-volumes in real-time using polygon-assisted raycasting using meshes as proxies to store selection information. These approaches enable sub-voxel accuracy in selecting and rendering volumetric regions using significantly smaller storage space compared to using lookup volume textures for selection. Proposed methods are applied to a gesture-based interaction interface, and user studies are undertaken to evaluate the effectiveness and intuitiveness of this interface in volume rotation and target localization tasks.