Nowadays, rasterization is the most common method used to achieve real-time semi-photorealistic effects in games or interactive applications. Some of those effects are not easily achievable, thus require more complicated methods and are difficult to obtain. The appearance of the presented worlds depends to a large extent on the approximation to the physical basis of light behaviour in them. The best effects in this regard are global illumination algorithms. Each of them including ray tracing give the most plausible effects, but at cost of higher computational complexity. Today’s hardware allows usage of ray tracing methods in-real time on Graphics Processing Units (GPU) thanks to its parallel nature. However, using ray tracing as a single rendering method may still result in poor performance, especially when used to create many image effects in complex environments. In this paper we present a hybrid approach for real-time rendering using both rasterization and ray tracing using heuristic, which determines whether to render secondary effects such as shadows, reflections and refractions for individual objects considering their relevancy and cost of rendering those effects for these objects in particular case.

No abstract

In computer graphics, the efficient rendering of a clear sky may greatly enhance the realism of synthesised interactive virtual environments. However, light atmospheric scattering, lying behind a reliable sky synthesis, is a computationally demanding process. Obtaining the highest possible accuracy and quality of the synthesised image in an efficient manner is not trivial as even minor integration errors may result in huge image artefacts. In this paper we propose two new approaches, namely the first based on the splines and the second on the Taylor expansion, in order to obtain the efficient computing of the transmittance (optical depth) component of the physically based single scattering model. We used Bruneton's framework [1] to compare the proposed solution with state-of-the-art methods in a single, scattering-based clear sky synthesis, in terms of image quality and performance (time). We managed to improve the quality of the single scattering effect and time performance and we removed the necessity of pre-calculating values to look-up tables for the transmittance part of the scattering integral, reducing exploited memory usage.

A qualitative comparison of three, popular and most widely known numerical integration methods in terms of atmospheric single scattering calculations is presented. A comparison of Midpoint, Trapezoidal and Simpson’s Rules taking into account quality of a clear sky generated images is performed. Methods that compute the atmospheric scattering integrals use Trapezoidal Rule. Authors try to determine which numerical integration method is the best for determining the colors of the sky and check if Trapezoidal Rule is in fact the best choice. The research does not only conduct experiments with Bruneton’s framework but also checks which of the selected numerical integration methods is the most appropriate and gives the lowest error in terms of atmospheric scattering phenomenon.

No abstract