In this paper, we present a novel point-based volume rendering technique based on particle generation from user-specified transfer function. In our presented technique, a set of tiny particles is generated from a given 3D scalar field. This particle generation process is based on a user-specified transfer function and rejection method. These particles are then projected onto the image plane to generate the final image. The main characteristic of our proposed technique is that particle projection order is independent and unfixed since the transparency values of particles are not taken into account. Therefore, only the depth-order comparison of particles is required during the particle projection stage and this greatly facilitates the parallel processing. When the quantity of projected particles is small, for instance one per pixel, it becomes difficult to reproduce the semi-transparent appearance which is the main characteristic of volume rendering. To overcome this problem, sub-sampling is applied in order to project several particles to a given pixel and the final color is obtained by averaging these partial color values.

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