Real-time Visualization of Clouds

Rendering realistic cloud images is a challenging computational intensive task. The high computational demand makes physics-based on-the-fly rendering impossible for real-time applications on low-cost workstations.
We present an approach to overcome this problem by using alpha-blended billboard textures. During a pre-processing step a series of pre-calculated images is generated for each cloud object of the scene. The images are showing each cloud object from different view points.
For a given camera position on the ground the final cloud depiction is composed by an appropriate subset of alpha-blended images, assigned to billboard textures. In so doing, we are able to create a smooth transition between arbitrary camera positions on the ground.