HDR light probe sequence resampling for realtime incident light field rendering

Abstract

Figure 1: A sequence of high dynamic range light probes is resampled to a three dimensional grid of radiance maps, which are projected onto spherical harmonics to allow for realtime rendering of incident light fields. The images show realtime rendered geometry with diffuse and glossy materials, lit using spherical harmonic grid representations of the incident light fields. AbstractThis paper presents a method for resampling a sequence of high dynamic range light probe images into a representation of Incident Light Field (ILF) illumination which enables realtime rendering. The light probe sequences are captured at varying positions in a real world environment using a high dynamic range video camera pointed at a mirror sphere. The sequences are then resampled to a set of radiance maps in a regular three dimensional grid before projection onto spherical harmonics. The capture locations and amount of samples in the original data make it inconvenient for direct use in rendering and resampling is necessary to produce an efficient data structure. Each light probe represents a large set of incident radiance samples from different directions around the capture location. Under the assumption that the spatial volume in which the capture was performed has no internal occlusion, the radiance samples are projected through the volume along their corresponding direction in order to build a new set of radiance maps at selected locations, in this case a three dimensional grid. The resampled data is projected onto a spherical harmonic basis to allow for realtime lighting of synthetic objects inside the incident light field.

Physically Based Rendering of Synthetic Objects in Real Environments

“…a dense grid of light probes [92,146,159,206,208]. The incident light at a point on a synthetic object can then be computed by interpolating the angular radiance distribution of spatially adjacent light probes [138]. However, for photorealistic results these techniques require a large number of light probes to be captured in the scene, leading to tedious measurement procedures and large memory requirements.…”

Efficient Visibility Encoding for Dynamic Illumination in Direct Volume Rendering

“…In this paper, we utilize a grid of spherical harmonic coefficients to encode self-shadowing of the volumetric data. Volumetric grids of spherical harmonics have also been used for rendering hair [26] and to encode spatially varying illumination [23]. Due to the large number of spherical harmonic coefficients needed for general scenes, compression methods based on clustered principal component analysis have previously been presented [36].…”

Learning based compression of surface light fields for real-time rendering of global illumination scenes

“…Both Clustered-EOB (CEOB) and Clustered-PCA (CPCA) allow for real-time reconstruction and rendering on commodity graphics hardware. We show that CEOB in most cases outperforms CPCA [Miandji et al 2011], K-SVD [Bryt and Elad 2008] and spherical harmonics [Sloan et al 2003;Löw et al 2009] in terms of memory footprint, reconstruction quality and rendering performance.…”

“…This is especially true for applications like interactive product visualization, where predictive results without any artifacts is an absolute requirement. A popular approach is to use appearance capture methods, [Chen et al 2002; * e-mail:ehsan.miandji@liu.se Unger et al 2008;Löw et al 2009], or to pre-compute detailed surface light fields (SLF) describing the appearance of virtual objects using full global illumination. A key problem, however, is that an SLF data set exhibit a very large memory footprint (often in the order of several GBs per object in the scene) and does not easily lend itself to real-time rendering.…”

“…In this paper we present a learning based algorithm for efficient compression of appearance information encoded as SLFs, which enables real-time rendering of virtual scenes exhibiting complex materials and light source configurations with full global illumination. Our algorithm is built upon the following requirements: the complexity of off-line pre-computations should not exceed that of standard methods for pre-computed radiance transfer (PRT) [Sloan et al 2003;Löw et al 2009], general high frequency scenes and materials must be handled, the technique must handle arbitrary light source configurations, and finally support real-time rendering. Surface light fields -An SLF is a 4D function f (u, v, φ, θ) that describes the visual appearance of an object as seen from any vantage point.…”