[show abstract][hide abstract] ABSTRACT: This paper describes the adaptation and evaluation of existing nested-surface visualization techniques for the problem of displaying intersecting surfaces. For this work, we collaborated with a neurosurgeon who is comparing multiple tumor segmentations with the goal of increasing the segmentation accuracy and reliability. A second collaborator, a physicist, aims to validate geometric models of specimens against atomic-force microscope images of actual specimens. These collaborators are interested in comparing both surface shape and inter-surface distances. Many commonly employed techniques for visually comparing multiple surfaces (side-by-side, wireframe, colormaps, uniform translucence) do not simultaneously convey inter-surface distance and the shapes of two or more surfaces. This paper describes a simple geometric partitioning of intersecting surfaces that enables the application of existing nested-surface techniques, such as texture-modulated translucent rendering of exteriors, to a broader range of visualization problems. Three user studies investigate the performance of existing techniques and a new shadow-casting glyph technique. The results of the first user study show that texture glyphs on partitioned, intersecting surfaces can convey inter-surface distance better than directly mapping distance to a red-gray-blue color scale on a single surface. The results of the second study show similar results for conveying local surface orientation. The results of the third user study show that adding cast shadows to texture glyphs can increase the understanding of inter-surface distance in static images, but can be overpowered by the shape cues from a simple rocking motion.
[show abstract][hide abstract] ABSTRACT: ImageSurfer is a tool designed to explore correlations between two 3D scalar fields. Our scientific goal was to determine where a protein is located, and how much its concentration varies along the membrane of a neuronal dendrite. The 3D scalar field data sets fall into two categories: dendritic plasma membranes (defining the structure) and immunofluorescent staining (defining protein concentration along the structure). ImageSurfer enables scientists to analyze relationships between multiple data sets obtained with confocal microscopy by providing 3D surface view, height field, and graphing tools. Each tool reduces the complexity of the problem by extracting a restricted subset of data: finding a region of interest in 3D; getting a sense of relative concentrations in 2D, and getting exact concentration values in 1D. The current design is presented, along with the rationale for each design decision. The tool is already proving useful for data exploration, analysis, and presentation.