M.: Volume rendering of smoke propagation CFD data

Figure 1: Six timesteps of smoke emission from a re inside a hall. The smoke propagation is simulated by computational uid dynamics and lit with an absorbtion and limited diuse scattering-based lighting model. Illuminated exit signs shine through dense smoke, which is modeled by adjusting the transfer function in front of exit signs. The evacuation of buildings in the event of a re requires careful planning of ventilation and evacuation routes during early archi-tectural design stages. Different designs are evaluated by simulat-ing smoke propagation using computational uid dynamics (CFD). Visibility plays a decisive role in nding the nearest re exit. This paper presents real-time volume rendering of transient smoke prop-agation conforming to standardized visibility distances. We visu-alize time dependent smoke particle concentration on unstructured tetrahedral meshes using a direct volume rendering approach. Due to the linear transfer function of the optical model commonly used in re protection engineering, accurate pre-integration of diffuse color across tetrahedra can be carried out with a single 2D texture lookup. We reduce rounding errors during framebuffer blending by applying randomized dithering if high accuracy frame buffers are unavailable on the target platform. A simple absorption-based light-ing model is evaluated in a preprocessing step using the same ren-dering approach. Back-illuminated exit signs are commonly used to indicate the escape route. As light emitting objects are visible further than reective objects, the transfer function in front of illu-minated exit signs must be adjusted with a deferred rendering pass