Interactive dynamic objects in a virtual light field Jamie Wither To cite this version: Jamie Wither. Interactive dynamic objects in a virtual light field. Graphics [cs.GR]. 2005. inria- 00598401 HAL Id: inria-00598401 https://hal.inria.fr/inria-00598401 Submitted on 6 Jun 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Interactive dynamic objects in a virtual light field Interactive dynamic objects in a virtual light field Year: 2005 Author: Jamie Wither Supervisor: Mel Slater This report is submitted as part requirement for the MSc Degree in Vision, Imaging and Virtual Environments at University College London. It is substantially the result of my own work except where explicitly indicated in the text. The report may be freely copied and distributed provided the source is explicitly acknowledged. 1/95 Interactive dynamic objects in a virtual light field Acknowledgements I would like to thank Pankaj Khanna and Jesper Mortensen for the many helpful discussions we had regarding their implementation of the virtual light field. I would also like to thank Mel Slater for his supervision and guidance while working on this project. 2/95 Interactive dynamic objects in a virtual light field Contents Contents ..............................................................................................................3 1 Introduction...................................................................................................5 1.1 Global illumination................................................................................ 5 1.2 The radiance equation............................................................................5 1.3 Classifying solutions.............................................................................. 7 1.3.1 Heckbert notation...........................................................................8 1.4 GI methods of solving the radiance equation..........................................8 1.4.1 Ray tracing..................................................................................... 8 1.4.2 Radiosity........................................................................................ 8 1.4.3 Path tracing.................................................................................... 9 1.4.4 Photon mapping.............................................................................9 1.5 Motivation for and contribution of this project..................................... 10 1.6 Approach............................................................................................. 11 1.7 Scope................................................................................................... 11 1.8 Report structure ................................................................................... 12 2 Background literature .................................................................................. 13 2.1 Radiosity ............................................................................................. 14 2.1.1 Computation ................................................................................ 14 2.1.2 Gathering and shooting ................................................................ 15 2.1.3 Meshing....................................................................................... 15 2.1.4 Altering geometry in Radiosity solutions...................................... 16 2.2 Raytracing ........................................................................................... 19 2.2.1 Scene traversal acceleration schemes............................................ 19 2.2.2 Optimizing ray tracing ................................................................. 21 2.2.3 Dedicated graphics hardware........................................................ 22 2.3 Shadows .............................................................................................. 23 2.3.1 Shadow mapping.......................................................................... 23 2.3.2 Shadow volumes.......................................................................... 24 2.4 The Virtual Light Field........................................................................ 25 2.4.1 Theory ......................................................................................... 25 2.4.2 Overview of the existing VLF code.............................................. 28 3 Implementation............................................................................................ 32 3.1 Adding a simple object to the existing scene ........................................ 32 3.1.1 Definition..................................................................................... 32 3.1.2 Wireframe Viewing...................................................................... 32 3.2 Moving the object................................................................................ 33 3.3 Adding the dynamic object to VLF shading modes .............................. 35 3.3.1 Flat shading and occlusion in progressive mode ........................... 35 3.3.2 Flat shading and occlusion in coherent mode................................ 38 3.4 Simple shading for the dynamic object................................................. 40 3.5 Casting shadows .................................................................................. 42 3.5.1 Shadow mapping implementation................................................. 43 3.5.2 Shadow ‘piercing'......................................................................... 45 3.5.3 Shadow blending.......................................................................... 45 3.5.4 Removing the reverse projection of the shadow............................ 46 3.5.5 Shadow map resolution................................................................ 47 3.6 Advanced diffuse shading using the VLF............................................. 47 3.6.1 Theory...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................47 3/95 Interactive dynamic objects in a virtual light field 3.6.2 Normalising for variation in solid angle in VLF directions. .......... 48 3.6.3 Normalising for the total projected unit cell area over hemisphere 49 3.6.4 Implementation of advanced shading............................................ 51 3.6.5 Reflections of the dynamic object in the static scene .................... 53 3.6.6 Increasing the number of sample points........................................ 54 3.6.7 Decreasing the number of sampled directions............................... 55 3.7 Scene energy balance considerations.................................................... 55 3.8 Summary ............................................................................................. 55 4 Results......................................................................................................... 57 4.1 Frame rendering times ......................................................................... 57 4.1.1 Progressive rendering frame times................................................ 58 4.1.2 Coherent rendering frame times ................................................... 60 4.1.3 Quantitative Summary.................................................................. 61 4.2 Qualitative Tests.................................................................................. 62 4.2.1 Luminance of dynamic diffuse cube............................................. 62 4.2.2 Colour bleeding for dynamic diffuse surfaces............................... 64 4.2.3 Shadows cast by the dynamic object............................................. 64 4.2.4 Shadows received by the dynamic object...................................... 65 4.2.5 Sampling half the VLF directions................................................. 66 4.2.6 Video........................................................................................... 66 4.2.7 Qualitative Summary ................................................................... 66 5 Conclusions.................................................................................................68 5.1 Further work........................................................................................ 69 5.1.1 Specular surfaces ......................................................................... 69 5.1.2 Static specular occlusion .............................................................. 69 5.1.3 Dynamic diffuse occlusion........................................................... 70 5.1.4 Hard shadow reflections..............................................................