Accelerating volume rendering by ray leaping with back steps

PubMedID: 19541384The methods for visualizing sampled spatial scientific data are known as volume rendering, where images are generated by computing 2D projections of 3D volume data. Since all the discrete data cells participate in the generation of each image, rendering time grows linearly with the resolution and complexity of the dataset. Empty cells in the data, which do not contribute to the final image, are of the important factors that increase the rendering time. During recent years, researchers have highly concentrated on improving the performance of these methods to achieve real time rendering. Skipping the empty space provides significant speedup and known as space leaping which requires implementation of special data structures and pre-processing. This paper presents a simple and efficient technique, that we name "ray-leaping," for the acceleration of total rendering process and eliminates the need for special data structures and pre-processing. © 2009 Elsevier Ireland Ltd. All rights reserved

Remote access computed tomography colonography

This thesis presents a novel framework for remote access Computed Tomography Colonography (CTC). The proposed framework consists of several integrated components: medical image data delivery, 2D image processing, 3D visualisation, and feedback provision. Medical image data sets are notoriously large and preserving the integrity of the patient data is essential. This makes real-time delivery and visualisation a key challenge. The main contribution of this work is the development of an efficient, lossless compression scheme to minimise the size of the data to be transmitted, thereby alleviating transmission time delays. The scheme utilises prior knowledge of anatomical information to divide the data into specific regions. An optimised compression method for each anatomical region is then applied. An evaluation of this compression technique shows that the proposed ‘divide and conquer’ approach significantly improves upon the level of compression achieved using more traditional global compression schemes. Another contribution of this work resides in the development of an improved volume rendering technique that provides real-time 3D visualisations of regions within CTC data sets. Unlike previous hardware acceleration methods which rely on dedicated devices, this approach employs a series of software acceleration techniques based on the characteristic properties of CTC data. A quantitative and qualitative evaluation indicates that the proposed method achieves real-time performance on a low-cost PC platform without sacrificing any image quality. Fast data delivery and real-time volume rendering represent the key features that are required for remote access CTC. These features are ultimately combined with other relevant CTC functionality to create a comprehensive, high-performance CTC framework, which makes remote access CTC feasible, even in the case of standard Web clients with low-speed data connections