Volume sculpting based on geometric tools

the analysis of volumetric datasets is the main concern in many areas ranging from geophysics to biomedical sciences. the direct visualization of these data plays an important role in this scenario, and in spite of developments in volume visualization techniques, interacting with large datasets still demands research efforts due to perceptual and performance issues. there is a need of interactive sculpting tools which can provide an intuitive way to examine and explore inner parts of the datasets, as well as to fill missing data for specific purposes. in this paper we report the development of interactive, intuitive and easy-to-use sculpting tools, which specify regions within the volume to be discarded from rendering, thus allowing inspection of the volume interior, and to be filled with material to build virtual structures in the volume. interactive rates for these sculpting tools were obtained by running special fragment programs on the graphics hardware. the tools were implemented using two interaction metaphors (virtual pointer and virtual hand) and following different approaches in terms of devices and single versus two-handed interaction. we report the evaluation of these approaches in detail and concluded that the use of two different devices together presents a better performance and are preferred by users. moreover, the use of virtual hand interaction provided better results than using the virtual pointer during the tests.