In order to take full advantage of GPU to realize fast and effective compression and reduce the limitation of network bandwidth, a fast and effective compression method based on KD-tree was presented. Firstly, the dynamic scene was divided by KD-tree at the first time step and small rigid bodies were constructed in each leaf in parallel. The mapping relations between rigid body leaves and the 3D divided grid were established to merge rigid bodies by using disjoint set. Finally, the compressed dynamic data were transmitted to the client to reconstruct the 3D dynamic scene within a certain period of time. The algorithm can greatly improve the speed of compression on the server, and effectively reduce the amount of data. The experimental results show that the proposed algorithm can not only guarantee the quality of the compression, but also compress dynamic datasets quickly and effectively which reduces the limitation of network bandwidth for the dynamic data.

Ink diffusion is a complex physical phenomenon. Concerning the problem of simulating ink diffusion on Xuan paper, this paper proposed a simulation method based on diffusion equation with variable coefficient, and its diffusion coefficient depended on Xuan paper structure and the residue of ink which reduced with time. There were two steps for simulation: simulating Xuan paper structure and simulating the dynamic procedure of diffusion. To simulate Xuan paper structure, a weighting fiber structure was proposed, which consisted of uniformly distributed line segments with different weights and random directions. The dynamic procedure of ink diffusion was described by the diffusion equation. To generate the diffusion image efficiently, Crank-Nicolson method was used to solve the diffusion equation, fiber structure was pre-computed, and the diffusion image was updated dynamically. Compared with the previous similar simulation methods, this method rendered more natural diffusion boundary, and overcame the problem of excessively smooth boundary. The experimental results demonstrate that this approach is able to simulate the effects of ink diffusion on different Xuan paper realistically.