Feedback Control of Cumuliform Cloud Formation based on Computational Fluid Dynamics

Yoshinori Dobashi (Hokkaido University)
Katsutoshi Kusumoto (Hokkaido University)
Tomoyuki Nishita (The University of Tokyo)
Tsuyoshi Yamamoto (Hokkaido University)


This document includes supplemental materials for our paper. To see each material, please click on the image.

A desktop PC with Intel Core2 Extreme X9650 and an nVidia GeForce 8800 GT is used to compute the examples. The simulations are carried out on the CPU. The GPU is used for displaying the results only.


Overview of our method

This pdf file explains the overview of our method. This material is basically the same as one shown in the main supplemental video.


Simple example

This animation corresponds to Figure 1 in the paper. The desired shape is relatively simple. In this case, the target shape is the height field. The shape of the clouds generated by our method is almost the same as the desired shape.


Complex example

This animation corresponds to Figure 7 in the paper. We specify a more characteristic shape. In this case, the target shape is not the height field. However, our method can generate clouds that closely match the desired shape. Since the clouds are generated in three-dimensions, we can render the clouds with arbitrary viewpoints and illumination as shown in this movie.


Comparisons with the previous method [Fattal et al. 2004]

For comparison, we implemented the method proposed by Fattal et al [2004] and combined with the cloud simulation. The left animation shows the result using the previous method. The right animation shows the result using our method. When using the previous methods, clouds are generated where they should not be. This is because the previous method do not take into account the cloud formation process. Our method can generate realistic-looking clouds. These examples correspond to Figure 6 in the paper


Unnatural shape of clouds

This animation shows an unnatural shape of clouds, the shape of a skull. In this case, the target shape is completely different from the height field. Although there are differences between the simulated clouds and the desired shape, our method succeeded in creating the convincing result. This animation corresponds to Figure 8(a)


A failure case

This animation shows a falure case. In this case, the rightmost part of the clouds does not match the target shape. This animation corresponds to Figure 8(b).


Clouds from photograph

This animation corresponds to Figure 9 in the paper. We generate clouds that resemble the real clouds in a photograph. The contour line of the real clouds is extracted. Then this contour line is used to control the simulation by our method.


360 view around clouds

The following animation shows the 360 view around the clouds shown in Figure 7 in the paper. This animation has been created to examine the shape of clouds viewed from various viewing directions. Although the shape tends to become the sweep of the contour line specified by the user, clouds are realistic even for the viewpoints other than the viewpoint used for specifying the desired shape.


Low resolution clouds

Fluid dynamics simulations on 3D grids have the well-known issue of behaving differently depending on the resolution of the grid. The following animation has been created to investigate the effect of the resolution on our control method. This animation is the low-resolution version of the simulation shown in Figure 1 in the paper. The simulation conditions are the same as those of Figure 1, except the number of grid points, that is 160x40x50. Our method succeeded in creating the convincing result even for this low-resolution simulation.