Abstract Subpixel rendering increases the apparent display resolution by taking into account the subpixel structure of a given display. In essence, each subpixel is addressed individually, allowing the underlying signal to be sampled more densely. Unfortunately, naïve subpixel sampling introduces colour aliasing, as each subpixel only displays a specific colour (usually R, G and B subpixels are used). As previous work has shown, chromatic aliasing can be reduced significantly by taking the sensitivity of the human visual system into account. In this work, we find optimal filters for subpixel rendering for a diverse set of 1D and 2D subpixel layout patterns. We demonstrate that these optimal filters can be approximated well with analytical functions. We incorporate our filters into GPU‐based multi‐sample anti‐aliasing to yield subpixel rendering at a very low cost (1–2 ms filtering time at HD resolution). We also show that texture filtering can be adapted to perform efficient subpixel rendering. Finally, we analyse the findings of a user study we performed, which underpins the increased visual fidelity that can be achieved for diverse display layouts, by using our optimal filters.

Abstract In this paper we present a novel method for high‐quality rendering of scenes with participating media. Our technique is based on instant radiosity, which is used to approximate indirect illumination between surfaces by gathering light from a set of virtual point lights (VPLs). It has been shown that this principle can be applied to participating media as well, so that the combined single scattering contribution of VPLs within the medium yields full multiple scattering. As in the surface case, VPL methods for participating media are prone to singularities, which appear as bright “splotches” in the image. These artifacts are usually countered by clamping the VPLs' contribution, but this leads to energy loss within the short‐distance light transport. Bias compensation recovers the missing energy, but previous approaches are prohibitively costly. We investigate VPL‐based methods for rendering scenes with participating media, and propose a novel and efficient approximate bias compensation technique. We evaluate our technique using various test scenes, showing it to be visually indistinguishable from ground truth.

In this paper we present a method that targets high-quality global illumination at interactive frame rates. As many techniques in this context, our method is based on instant radiosity, which represents the indirect illumination in a scene with a set of virtual point lights, and therefore enables efficient GPU rendering. Instant radiosity captures light transport over larger distances well, but it requires clamping of the point lights' contribution to avoid bright splotches on nearby surfaces. By bounding the short distance light transport, the algorithm removes some energy and thus introduces bias, that is visible as incorrect darkening near edges and corners. Our method improves the quality and correctness of the rendered images by removing bias using a hierarchical screen space approach. We show that the bias compensation can be formulated as a post-processing step and demonstrate renderings comparable to results from offline algorithms at interactive speed.

Scattering in participating media, such as fog or haze, generates volumetric lighting effects known as crepuscular or god rays. Rendering such effects greatly enhances the realism in virtual scenes, but is inherently costly as scattering events occur at every point in space and thus it requires costly integration of the light scattered towards the observer. This is typically done using ray marching which is too expensive for every pixel on the screen for interactive applications. We propose a rendering technique for textured light sources in single-scattering media, that draws from the concept of epipolar geometry to place samples in image space: the inscattered light varies orthogonally to crepuscular rays, but mostly smoothly along these rays. These are epipolar lines of a plane of light rays that projects onto one line on the image plane. Our method samples sparsely along epipolar lines and interpolates between samples where adequate, but preserves high frequency details that are caused by shadowing of light rays. We show that our method is very simple to implement on the GPU, yields high quality images, and achieves high frame rates.

Efficient visibility queries are key in many interactive rendering techniques, such as occlusion culling, level of detail determination, and perceptual rendering. The occlusion query mechanism natively supported by GPUs is carried out for batches of rendered geometry. In this paper, we present two novel ways of determining visibility by intelligently querying summed area tables and computing a variant of item buffers. This enables visibility queries of finer granularity, e.g., for sub-regions of objects and for instances created within a single draw call. Our method determines the visibility of a large number of objects simultaneously which can be used in geometry shaders to cull triangles, or to control the level of detail in geometry and pixel shaders under certain rendering scenarios. We demonstrate the benefits of our method with two different real-time rendering techniques.

Recent approaches to global illumination for dynamic scenes achieve interactive frame rates by using coarse approximations to geometry, lighting, or both, which limits scene complexity and rendering quality. High-quality global illumination renderings of complex scenes are still limited to methods based on ray tracing. While conceptually simple, these techniques are computationally expensive. We present an efficient and scalable method to compute global illumination solutions at interactive rates for complex and dynamic scenes. Our method is based on parallel final gathering running entirely on the GPU. At each final gathering location we perform micro-rendering: we traverse and rasterize a hierarchical point-based scene representation into an importance-warped micro-buffer , which allows for BRDF importance sampling. The final reflected radiance is computed at each gathering location using the micro-buffers and is then stored in image-space. We can trade quality for speed by reducing the sampling rate of the gathering locations in conjunction with bilateral upsampling. We demonstrate the applicability of our method to interactive global illumination, the simulation of multiple indirect bounces, and to final gathering from photon maps.