Volumetric data abounds in medical imaging and other fields. With the improved imaging quality and the increased resolution, volumetric datasets are getting so large that the existing tools have become inadequate for processing and analyzing the data. Here we consider the problem of computing tetrahedral meshes to represent large volumetric datasets with labeled multiple materials, which are often encountered in medical imaging or microscopy optical slice tomography. Such tetrahedral meshes are a more compact and expressive geometric representation so are in demand for efficient visualization and simulation of the data, which are impossible if the original large volumetric data are used directly due to the large memory requirement. Existing methods for meshing volumetric data are not scalable for handling large datasets due to their sheer demand on excessively large run-time memory or failure to produce a tet-mesh that preserves the multi-material structure of the original volumetric data. In this article we propose a novel approach, called Marching Windows, that uses a moving window and a disk-swap strategy to reduce the run-time memory footprint, devise a new scheme that guarantees to preserve the topological structure of the original dataset, and adopt an error-guided optimization technique to improve both geometric approximation error and mesh quality. Extensive experiments show that our method is capable of processing very large volumetric datasets beyond the capability of the existing methods and producing tetrahedral meshes of high quality.

The availability of commodity 3D extruder pen allows direct drawing of 3D wire sculptures for novice users, enabling many novel applications such as intuitive spatial intelligence development for school students. However, the lack of spatial and structural cues among individual pen strokes makes the 3D drawing process challenging, which often leads to highly distorted and even incomplete wire sculptures. We present a mixed reality system, called `WireDraw', to immersively guide the 3D drawing for easy wire sculpturing. The system design is based on novel 3D drawing principles and the subsequent optimization, making the stroke sequence of the wire model drawable and easy to draw. On-the-fly edits on unsatisfactory strokes are also allowed for creative design. We demonstrate the effectiveness of our system by testing on a variety of wire models and a user study. The results show that the visual guidance provided by our system is extremely helpful for drawing high-quality wire sculptures.

Due to the development of 3D sensing and modeling techniques, the state-of-the-art mixed reality devices such as Microsoft Hololens have the ability of digitalizing the physical world. This unique feature bridges the gap between virtuality and reality and largely elevates the user experience. Unfortunately, the current solution only performs well if the virtual contents complement the real scene. It can easily cause visual artifacts when the reality needs to be modified due to the virtuality (e.g., remove real objects to offer more space for virtual objects), a common scenario in mixed reality applications such as room redecoration and environment design. We present a novel system, called emph{SceneCtrl}, that allows the user to interactively edit the real scene sensed by Hololens, such that the reality can be adapted to suit virtuality. Our proof-of-concept prototype employs scene reconstruction and understanding to enable efficient editing such as deleting, moving, and copying real objects in the scene. We also demonstrate emph{SceneCtrl} on a number of example scenarios in mixed reality, verifying the enhanced experience by resolving conflicts between virtuality and reality.