29,719 research outputs found
Neural Microfacet Fields for Inverse Rendering
We present Neural Microfacet Fields, a method for recovering materials,
geometry, and environment illumination from images of a scene. Our method uses
a microfacet reflectance model within a volumetric setting by treating each
sample along the ray as a (potentially non-opaque) surface. Using surface-based
Monte Carlo rendering in a volumetric setting enables our method to perform
inverse rendering efficiently by combining decades of research in surface-based
light transport with recent advances in volume rendering for view synthesis.
Our approach outperforms prior work in inverse rendering, capturing high
fidelity geometry and high frequency illumination details; its novel view
synthesis results are on par with state-of-the-art methods that do not recover
illumination or materials.Comment: Project page: https://half-potato.gitlab.io/posts/nmf
Path-tracing Monte Carlo Library for 3D Radiative Transfer in Highly Resolved Cloudy Atmospheres
Interactions between clouds and radiation are at the root of many
difficulties in numerically predicting future weather and climate and in
retrieving the state of the atmosphere from remote sensing observations. The
large range of issues related to these interactions, and in particular to
three-dimensional interactions, motivated the development of accurate radiative
tools able to compute all types of radiative metrics, from monochromatic, local
and directional observables, to integrated energetic quantities. In the
continuity of this community effort, we propose here an open-source library for
general use in Monte Carlo algorithms. This library is devoted to the
acceleration of path-tracing in complex data, typically high-resolution
large-domain grounds and clouds. The main algorithmic advances embedded in the
library are those related to the construction and traversal of hierarchical
grids accelerating the tracing of paths through heterogeneous fields in
null-collision (maximum cross-section) algorithms. We show that with these
hierarchical grids, the computing time is only weakly sensitivive to the
refinement of the volumetric data. The library is tested with a rendering
algorithm that produces synthetic images of cloud radiances. Two other examples
are given as illustrations, that are respectively used to analyse the
transmission of solar radiation under a cloud together with its sensitivity to
an optical parameter, and to assess a parametrization of 3D radiative effects
of clouds.Comment: Submitted to JAMES, revised and submitted again (this is v2
Exposure Render: An Interactive Photo-Realistic Volume Rendering Framework
The field of volume visualization has undergone rapid development during the past years, both due to advances in suitable computing hardware and due to the increasing availability of large volume datasets. Recent work has focused on increasing the visual realism in Direct Volume Rendering (DVR) by integrating a number of visually plausible but often effect-specific rendering techniques, for instance modeling of light occlusion and depth of field. Besides yielding more attractive renderings, especially the more realistic lighting has a positive effect on perceptual tasks. Although these new rendering techniques yield impressive results, they exhibit limitations in terms of their exibility and their performance. Monte Carlo ray tracing (MCRT), coupled with physically based light transport, is the de-facto standard for synthesizing highly realistic images in the graphics domain, although usually not from volumetric data. Due to the stochastic sampling of MCRT algorithms, numerous effects can be achieved in a relatively straight-forward fashion. For this reason, we have developed a practical framework that applies MCRT techniques also to direct volume rendering (DVR). With this work, we demonstrate that a host of realistic effects, including physically based lighting, can be simulated in a generic and flexible fashion, leading to interactive DVR with improved realism. In the hope that this improved approach to DVR will see more use in practice, we have made available our framework under a permissive open source license
The Iray Light Transport Simulation and Rendering System
While ray tracing has become increasingly common and path tracing is well
understood by now, a major challenge lies in crafting an easy-to-use and
efficient system implementing these technologies. Following a purely
physically-based paradigm while still allowing for artistic workflows, the Iray
light transport simulation and rendering system allows for rendering complex
scenes by the push of a button and thus makes accurate light transport
simulation widely available. In this document we discuss the challenges and
implementation choices that follow from our primary design decisions,
demonstrating that such a rendering system can be made a practical, scalable,
and efficient real-world application that has been adopted by various companies
across many fields and is in use by many industry professionals today
Geant4 Applications for Modeling Molecular Transport in Complex Vacuum Geometries
We discuss a novel use of the Geant4 simulation toolkit to model molecular
transport in a vacuum environment, in the molecular flow regime. The Geant4
toolkit was originally developed by the high energy physics community to
simulate the interactions of elementary particles within complex detector
systems. Here its capabilities are utilized to model molecular vacuum transport
in geometries where other techniques are impractical. The techniques are
verified with an application representing a simple vacuum geometry that has
been studied previously both analytically and by basic Monte Carlo simulation.
We discuss the use of an application with a very complicated geometry, that of
the Large Synoptic Survey Telescope camera cryostat, to determine probabilities
of transport of contaminant molecules to optical surfaces where control of
contamination is crucial.Comment: 7 pages, 4 figures, 2 tables, to appear in IJMSSC, updated to
accepted versio
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