Hardware Acceleration of Progressive Refinement Radiosity using Nvidia RTX

A vital component of photo-realistic image synthesis is the simulation of indirect diffuse reflections, which still remain a quintessential hurdle that modern rendering engines struggle to overcome. Real-time applications typically pre-generate diffuse lighting information offline using radiosity to avoid performing costly computations at run-time. In this thesis we present a variant of progressive refinement radiosity that utilizes Nvidia's novel RTX technology to accelerate the process of form-factor computation without compromising on visual fidelity. Through a modern implementation built on DirectX 12 we demonstrate that offloading radiosity's visibility component to RT cores significantly improves the lightmap generation process and potentially propels it into the domain of real-time.Comment: 114 page

Progressive photon mapping for daylight redirecting components

AbstractDaylight redirecting components (DRCs) are characterised by complex transmissive and reflective behaviour that is difficult to predict accurately largely due to their highly directional scattering, and the caustics this produces. This paper examines the application of progressive photon mapping as a state of the art forward raytracing technique to efficiently simulate the behaviour of such DRCs, and how this approach can support architects in assessing their performance.Progressive photon mapping is an iterative variant of static photon mapping that effects noise reduction through accumulation of results, as well as a reduction in bias inherent to all density estimation methods by reducing the associated bandwidth at a predetermined rate. This not only results in simplified parametrisation for the user, but also provides a preview of the progressively refined simulation, thus making the tool accessible to non-experts as well.We demonstrate the effectiveness of this technique with an implementation based on the Radiancephoton mapping extension and a case study involving retroreflecting prismatic blinds as a representative DRC

Accelerating Hash Grid and Screen-Space Photon Mapping in 3D Interactive Applications with OpenCL

Achieving interactive and realistic rendering is only possible with a combination of rendering algorithms, rendering pipelines, multi-core hardware, and parallelization APIs. This project explores and implements two photon mapping pipelines based on the work of Mara et. al [5] and Singh et. al [7] to achieve interactive rendering performance for a set of simple scenes using OpenCL and C++ to work with a GPU. In particular, both a 3D hash grid and a screen-space tiling algorithm are parallelized to accelerate photon lookup in order to compute direct and indirect lighting on visible surfaces in a scene. By using OpenCL with photon mapping interactive renderings of scenes were produced and updated live as a user moved a virtual camera. This work with OpenCL paved the way for developing a raytracing pipeline in OpenGL and for future work on the latest research in realtime realistic rendering

Importance driven environment map sampling

In this paper we present an automatic and efficient method for supporting Image Based Lighting (IBL) for bidirectional methods which improves both the sampling of the environment, and the detection and sampling of important regions of the scene, such as windows and doors. These often have a small area proportional to that of the entire scene, so paths which pass through them are generated with a low probability. The method proposed in this paper improves this by taking into account view importance, and modifies the lighting distribution to use light transport information. This also automatically constructs a sampling distribution in locations which are relevant to the camera position, thereby improving sampling. Results are presented when our method is applied to bidirectional rendering techniques, in particular we show results for Bidirectional Path Tracing, Metropolis Light Transport and Progressive Photon Mapping. Efficiency results demonstrate speed up of orders of magnitude (depending on the rendering method used), when compared to other methods

Photorealistic physically based render engines: a comparative study

Pérez Roig, F. (2012). Photorealistic physically based render engines: a comparative study. http://hdl.handle.net/10251/14797.Archivo delegad

Goce precise non-gravitational force modeling for POD applications

GOCE was launched in 2009 at 250 km altitude to recover Earth’s static gravity field. As part of the GOCE-Italy project, we carried out the precise modeling for the radiation pressure and the aerodynamic effects on this satellite. This analysis has been performed to reduce the mismodeling of the non-gravitational forces, in order to be able to estimate the ocean tides parameters from the LEO satellites orbital perturbation. A new software ARPA (Aerodynamics and Radiation Pressure Analysis), which takes advantage of the raytracing technique, has been designed and developed to accurately model the non-gravitational perturbations. ARPA can compute the Solar Radiation Pressure (SRP), Earth Radiation Pressure (ERP), the spacecraft Thermal Re-Radiation (TRR) and the aerodynamic forces and torques acting on any satellite with a high level of accuracy. The adopted methodologies and procedure are presented in this thesis, and the results of the tests on GOCE are illustrated and discussed. The NAPEOS (NAvigation Package for Earth Observation Satellites) software, developed and maintained at ESA/ESOC, was upgraded to make use of the new ARPA inputs and adopted to perform the tests on GOCE. The tests were performed on 30 consecutive daily arcs, starting at the beginning of the GOCE science phase on 1st November 2009. The results for the radiation test cases show a significant reduction of the empirical accelerations, especially in the cross-track direction, of about the 20% for the SRP, 12% for the ERP albedo, 13% for the ERP infrared and 20% for the TRR with respect to the standard NAPEOS force modeling (cannon-ball). For the aerodynamics, an important reduction of the post-fit RMS from 7.6 to 7.3 mm has been observed with the new ARPA model, and the a reduction from 4.6 to 4.2 cm of the distance of the orbits computed with ARPA from the official reduced-dynamics GOCE orbits (Precise Science Orbit) has been computed. The obtained results confirm the goodness of the modeling and techniques of ARPA for all the non-gravitational perturbations computed for GOCE. Even though the results are presented for the GOCE satellite, the new technique and software are adaptable to satellite of any shape, whether in Earth-bound orbit, or orbiting another planet, or cruising in interplanetary space