The assessment of images of complex materials on an absolute scale is difficult for a human observer. Comparing physical and virtual samples side-by-side simplifies the task by introducing a ...reference. The goal of this article is to study the influence of image exposure on the perception of realism on images of paint materials containing sparkling metallic flakes. We use a radiometrically calibrated DSLR camera to acquire high resolution raw photographs of our physical samples which provide us with radiometric information from the samples. This is combined with the data obtained from the calibration of a stereoscopic display and shutter glasses to transform the raw photographs into images that can be shown by the display, controlling the colorimetric output signal. This ensures that we can transform our data back and forth between a radiometric and a colorimetric representation, minimizing the loss of information throughout the chain of acquisition and visualization. In this article we propose a paired comparison scenario that improves the results from our previous work, focusing on three main aspects: stereoscopy, exposure time, and dynamic range. Our results show that observers consider stereoscopy as the most important factor of the three for judging the similarity of these images to the reference, followed by exposure time and dynamic range, which supports our claims from previous research.
This paper covers the time consuming issues intrinsic to physically-based image rendering algorithms. First, glass materials optical properties were measured on samples of real glasses and other ...objects materials inside an hotel room were characterized by deducing spectral data from multiple trichromatic images. We then present the rendering model and ray-tracing algorithm implemented in Virtuelium, an open source software. In order to accelerate the computation of the interactions between light rays and objects, the ray-tracing algorithm is parallelized by means of domain decomposition method techniques. Numerical experiments show that the speedups obtained with classical parallelization techniques are significantly less significant than those achieved with parallel domain decomposition methods.
Spectral Domain Decomposition Method for Natural Lighting and Medieval Glass Rendering Benissan, Guillaume Gbikpi; Cerise, Remi; Callet, Patrick ...
2014 IEEE Intl Conf on High Performance Computing and Communications, 2014 IEEE 6th Intl Symp on Cyberspace Safety and Security, 2014 IEEE 11th Intl Conf on Embedded Software and Syst (HPCC,CSS,ICESS),
2014-Aug.
Conference Proceeding
Odprti dostop
In this paper, we use an original ray-tracing domain decomposition method to address image rendering of naturally lighted scenes. This new method allows to particularly analyze rendering problems on ...parallel architectures, in the case of interactions between light-rays and glass material. Numerical experiments, for medieval glass rendering within the church of the Royaumont abbey, illustrate the performance of the proposed ray-tracing domain decomposition method (DDM) on multi-cores and multi-processors architectures. On one hand, applying domain decomposition techniques increases speedups obtained by parallelizing the computation. On the other hand, for a fixed number of parallel processes, we notice that speedups increase as the number of sub-domains do.
Despite the notable progress in physically-based rendering, there is still a long way to go before we can automatically generate predictable images of biological materials. In this thesis, we address ...an open problem in this area, namely the spectral simulation of light interaction with human skin, and propose a novel biophysically-based model that accounts for all components of light propagation in skin tissues, namely surface reflectance, subsurface reflectance and transmittance, and the biological mechanisms of light absorption by pigments in these tissues. The model is controlled by biologically meaningful parameters, and its formulation, based on standard Monte Carlo techniques, enables its straightforward incorporation into realistic image synthesis frameworks. Besides its biophysicallybased nature, the key difference between the proposed model and the existing skin models is its comprehensiveness, i. e. , it computes both spectral (reflectance and transmittance) and scattering (bidirectional surface-scattering distribution function) quantities for skin specimens. In order to assess the predictability of our simulations, we evaluate their accuracy by comparing results from the model with actual skin measured data. We also present computer generated images to illustrate the flexibility of the proposed model with respect to variations in the biological input data, and its applicability not only in the predictive image synthesis of different skin tones, but also in the spectral simulation of medical conditions.
Physically based renderers produce high quality images with high dynamic range (HDR) values. Therefore, these images need to be tone mapped in order to be displayed on low dynamic range (LDR) ...displays. A typical approach is to blindly apply tone mapping operators without taking advantage of the extra information that comes for free from the modeling process for creating a 3D scene. In this paper, we propose a novel pipeline for tone mapping high dynamic range (HDR) images which are generated using physically based renderers. Our work exploits information of a 3D scene, such as geometry, materials, luminaries, etc. This allows to limit the assumptions that are typically made during the tone mapping step. As consequence of this, we will show improvements in term of quality while keeping the entire process straightforward.
The RADIANCE lighting simulation and rendering system Ward, Gregory J.
International Conference on Computer Graphics and Interactive Techniques: Proceedings of the 21st annual conference on Computer graphics and interactive techniques,
07/1994
Conference Proceeding
Odprti dostop
This paper describes a physically-based rendering system tailored to the demands of lighting design and architecture. The simulation uses a light-backwards ray-tracing method with extensions to ...efficiently solve the rendering equation under most conditions. This includes specular, diffuse and directional-diffuse reflection and transmission in any combination to any level in any environment, including complicated, curved geometries. The simulation blends deterministic and stochastic ray-tracing techniques to achieve the best balance between speed and accuracy in its local and global illumination methods. Some of the more interesting techniques are outlined, with references to more detailed descriptions elsewhere. Finally, examples are given of successful applications of this free software by others.
Simulating the aurora Baranoski, Gladimir V. G.; Rokne, Jon G.; Shirley, Peter ...
The Journal of visualization and computer animation,
02/2003, Letnik:
14, Številka:
1
Journal Article
Metropolis light transport Veach, Eric; Guibas, Leonidas J.
International Conference on Computer Graphics and Interactive Techniques: Proceedings of the 24th annual conference on Computer graphics and interactive techniques,
08/1997
Conference Proceeding
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