Volume Rendering And Clipping For Air Pollution Visualization

In recent decades, with the development of visualization, people have paid much attention to visualization for air pollution control and environment monitoring. Visualization of weather data makes air quality monitoring intuitive, and helps people to make decisions or forecast pollution more easily.2D display of scientific data can no longer satisfy the increasing requirement on realistic and immersive observation of large-scale data sets. Instead, with great development in graphics processing units, rendering scientific data in3D has become more and more popular. However, scientific data visualization in3D is much more complex, especially when the input data sets are large-scale. Consequently, interactive rendering of large-scale data has been one of the research focuses in scientific data visualization.In this paper, we concentrate on visualizing3D weather data through direct volume rendering, and solve the rendering problem inside the volume with a novel clipping method. There are many methods for air pollution visualization. Direct volume rendering where each point in space is assigned a density for the emission and absorption of light and the volume renderer computes the light reaching the eye along viewing rays [1,2]. Direct volume rendering is an attractive technique because it can convey a great deal of information in a single image by mapping the scalar data values in a sample volume to color and opacity [3]. It is especially suitable as we use large static data sets for rendering.Volume clipping most apparently shows the three dimensionality and volumetric property of volume. It cuts away selected parts of a volume and uncovers important parts or details we should see as the viewpoint changes. Most clipping methods are depth-based or importance-driven, however, there are few specific and fast clipping methods for3D scene walkthrough in a volume. We generate a novel volume clipping method based on viewpoint for3D scene walkthrough. We create a new3D texture as a container for the volume with different sizes according to transformations of viewpoint, and avoid changing the volumetric data. Viewer could always see the volume part in front of his viewpoint.