Adaptive Cube Tessellation for Topologically Correct Isosurfaces

Three dimensional datasets representing scalar fields are frequently rendered using isosurfaces. For datasets arranged as a cubic lattice, the marching cubes algorithm is the most used isosurface extraction method. However, the marching cubes algorithm produces some ambiguities which have been solved using different approaches that normally imply a more complex process. One of them is to tessellate the cubes into tetrahedra, and by using a similar method (marching tetrahedra), to build the isosurface. The main drawback of other tessellations is that they do not produce the same isosurface topologies as those generated by improved marching cubes algorithms. We propose an adaptive tessellation that, being independent of the isovalue, preserves the topology. Moreover the tessellationallows the isosurface to evolve continuously when the isovalue is changed continuously.

VR Based Visualization and Exploration of Plant Biological Data

This paper investigates the use of virtual reality (VR) technologies to facilitate the analysis of plant biological data in distinctive steps in the application pipeline. Reconstructed three-dimensional biological models (primary polygonal models) transferred to a virtual environment support scientists' collaborative exploration of biological datasets so that they obtain accurate analysis results and uncover information hidden in the data. Examples of the use of virtual reality in practice are provided and a complementary user study was performed.

A Stereoscopic Volume Rendered Brain Atlas

The anatomy of the human brain is organized as a complex arrangement of interrelated structures in three dimensional space. To facilitate the understanding of both structure and function, we have created a volume rendered brain atlas (VRBA) with an intuitive interface that allows real-time stereoscopic rendering of brain anatomy. The VRBA incorporates 2-dimensional and 3-dimensional texture mapping to display segmented brain anatomy co-registered with a T1 MRI. The interface allows the user to remove and add any of the 62 brain structures, as well as control the display of the MRI dataset. The atlas also contains brief verbal and written descriptions of the different anatomical regions to correlate structure with function. A variety of stereoscopic projection methods are supported by the VRBA and provide an abstract, yet simple, way of visualizing brain anatomy and 3-dimensional relationships between different nuclei.

The Value of Negotiating Cost-Based Transfer Prices

This paper analyzes the potential of one-step transfer prices based on either variable or full costs for coordinating decentralized production and quality-improving investment decisions. Transfer prices based on variable costs fail to induce investments on the upstream stage. In contrast, transfer prices based on full costs provide strong investment incentives for the upstream divisions. However, they fail to coordinate the investment decisions. We show that negotiations prevent such coordination failure. In particular, we find that the firm benefits from a higher degree of decentralization so that total profit increases in the number of parameters being subject to negotiations.