Three-dimensional Data Field Visualization Based On The Ray Casting Technology

With the rapid development of modern science and technology and the use ofvarious kinds of advanced measuring equipments such as Computed Tomography(CT), Magnetic Resonance Imaging (MRI), Computer Simulation (such as nuclearexplosion), geophysical exploration instrument and so on, thus making thethree-dimensional data derived from the area of biological medical, aerospace,resource exploration, meteorological survey and scientific simulation are easy to get.But data collection is just a process, the effective analysis and use of these hugeamounts of three-dimensional data field information is the ultimate goal of access todata, it is also one of the most challenging scientific issues of the21st century.Three-dimensional data field visualization is the first link and it provides the intuitivedisplay of the overall structure of the three-dimensional data field to assist theresearchers to to analyse and use the deep key information contained in the complexdata effectively. The article focuses on the three-dimensional data field, establishes acontinuous model based on seven-dimensional Box spline for three-dimensional datafield and makes high-precision visualization analysis in the model. Volume renderingtechnique is one of the hot spots in three-dimensional data field visualization, and RayCasting algorithm is commonly used, which has a broad application prospect.The traditional method of volumetric data iso-surface visualization based on RayCasting using tri-linear interpolation for intersection calculation. This methodproduces large error. Aimed at the defect of traditional algorithm, this paper proposesa method based on the seven-directional Box spline to implement the iso-surfacevisualization algorithm in order to improve the interpolation and gradient calculationaccuracy. It uses color mapping transfer function with the combination of a variety ofvolumetric data attribute value and gradient magnitude. Because the seven-directionalBox spline hasC2continuity and is better than three three times B-spline, and thealgorithm can achieve high precision level visualization effect, so it achieves thehigher accuracy compared with other existing algorithms. In addition, it is moreaccurate and reliable to calculate the gradient, normal and curvature onthis continuous model. This algorithm can achieve high precision level of iso-surfaceand various properties’ visualization, it also gives rich instances to illustrate the effectof the improved algorithm.