Target Feature Based Multi-resolution Volume Rendering

Volume rendering is a technique which is used to display three-dimensional volume, it has excellent ability to handling this kind of volume. This technology is now widely used in many fields, such as medicine, geophysics, engineering, and fluid physics. Thanks to the development of the processing power of graphics chip,the speed and quality of volume rendering technology has been greatly improved. However, a major problem of this technology is the amount of data. With the development of detection and signal processing technology, the size of three-dimensional volume increases rapidly, and its growth rate is much greater than the growth rate of hardware’s storage capacity. How can we complete the volume rendering work of massive data in limited memory, has become a focus of current research work.Multi-resolution volume rendering technique is an effective way to solve this problem. By dividing the data in to small blocks, and represented each block by the multi-resolution, this method can effectively reduce the overall amount of data. However, the conventional multi-resolution volume rendering methods rely on the the changing rate of the data. It can achieve excellent compression ratio to the data whose changing rate is small and contains more homogeneous regions. But to those data who contains little homogeneous regions(such as seismic signal data in geophysical field), multi-resolution approach based on either the Shannon entropy or MSE can effectively achieve the effect of reducing the amount of data.This paper has done some research on these problems, and in addition, this article also solved some other problems in traditional multi-resolution volume rendering method:(1). In this paper, a target-based multi-resolution volume rendering method is proposed based on the traditional method. It’s basic idea is to use the target feature of the data as a guide to find the target areas. This method can guaranteed the smooth progress of rendering work in case of limited storage space. This method can meet the demand of computer memory by reducing the amount of data to non critical region, and to protect the data in target region as far as possible. In this way, we can achieve multi-resolution volume rendering effectively without losing the critical information of target areas. Under the premise of guarantee the amount of data, this method can get a better rendering results by dropping the amount of information in the non-target area, and to ensure high drawing quality of the target region. Experimental results show that compared with traditional methods, the proposed method can get better drawing effects in critical areas, while further reducing the amount of data used to draw.(2). Based on results of previous studies, we use a fusion approach which gradual change in the level of detail of adjacent block to reduce artifacts between adjacent bricks.Also, since the introduction of the target features,it will increase the independence of the blocking process, and increase the blocking artifacts. We also improved this problem in this paper.(3). During the test we found that it is difficult for user to estimate the final render result by the error threshold in traditional multi-resolution volume rendering method. So, we propose an adaptive block level-of-detail selection algorithm, using the spatial parameters to replaces the error threshold, under certain storage limit, each sub-adaptive selection level-of-detail block that results in the minimum final error. In addition, this algorithm also provides the preparation work for the last methods.