| Titre : | Cascaded Soft Shadow Maps Based On PCF Filtering |
| Auteurs : | Nadia AZRI, Auteur ; Abdelmoumen Zerari, Directeur de thèse |
| Type de document : | Monographie imprimée |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2020 |
| Format : | 1 vol. (69 p.) / ill. / 29 cm |
| Langues: | Anglais |
| Mots-clés: | soft shadow,real-time rendering,cascaded shadow maps,GPU. |
| Résumé : | Soft shadows are one of the key features that distinguish realistic images from those that look unnatural. An ever-increasing number of algorithms have been proposed for the task, but the computation of physically-based soft shadows remains costly due to the large number of samples required from the area light source and is avoided in production whenever possible.In practice, soft shadow effects are most often produced using approximate methods from global illumination.Physically accurate soft shadows in real-time applications can be imitated by subdividing the area light source into multiple samples and creating a shadow map for each sample and then accumulating them. In this work, we fitted in this context, and we proposed a new technique to reduce the rendering time required to achieve a high quality of soft shadows in real-time rendering. We generated physically accurate soft shadows using the Cascaded Shadow Maps technique (CSMs) to reduce further the samples of the area light source on far cascades, and use multiple implemented PCF filters on the GPU which allowed us reducing the samples by removing the artifacts and soften the resulting soft shadows.Both the CSMs technique and the PCF filtering freed-up significant computing time. The results show that our technique improves efficiency by creating high-quality soft shadows in real-time, and is undoubtedly faster than traditional techniques. |
| Sommaire : |
Introduction 1
1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Aim and Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 Structure of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 Illumination 4 1.1 Introduction . . . .. . . . . . . . . . . . . . . . . . . . . . 5 1.2 Illumination . . . . . . . .. . . . . . . . . . . . . . . . . . . . 5 1.2.1 Local illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.1.1 Illumination models . . . . . . . . . . . . . . . . . . . . . 6 1.2.1.1.1 Ambient light . . . . . . . . . . . . . . . . . . . . 6 1.2.1.1.2 Diffuse model . . . . . . . . . . . . . . . . . . . . 7 1.2.1.1.3 Specular reflection . . . . . . . . . . . . . . . . . 7 1.2.1.1.4 Phong illumination model . . . . . . . . . . . . . 8 1.2.2 Global illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2.3 Light sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3 Shading methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.1 Flat shading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.2 Gouraud shading . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.3 Phong shading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.4 Basic definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.4.1 Geometric quantities: solid angle . . . . . . . . . . . . . . . . . . . 14 1.4.2 Radiometric quantities . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.5 The rendering equation . . . . . . . . . . . . . . . . . . . . . . 16 1.5.1 Bidirectional reflectance distribution function (BRDF) . . . . . . . 16 1.5.1.1 BRDF models . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.5.2 Rendering equation . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.5.3 Integration by the Monte Carlo method . . . . . . . . . . . . . . . . 19 1.6 Global illumination algorithms . . . . . . . . . . . . . . . . . . . . 19 1.6.1 Radiosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.6.2 Path tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.6.3 Photon mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.6.4 Shadows in global illumination algorithms . . . . . . . . . . . . . . 21 1.6.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1.7 Conclusion . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 24 2 Real-time shadows 25 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 26 2.2 General information on shadows . . . . . . . . . . . . . . . . . . . . . . . . 26 2.2.1 Definition of shadow . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.2.2 Types of shadows . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.2.3 Importance of shadow effects . . . . . . . . . . . . . . . . . . . . . . 28 2.2.4 Hard shadows vs. soft shadows . . . . . . . . . . . . . . . . . . . . 30 2.3 Shadows in real-time . . . . . . . . . . . . . . . . . . . . . . 32 2.3.1 Object space and image space . . . . . . . . . . . . . . . . . . . . . 32 2.3.2 Shadows volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.3 Shadow Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.3.3.1 Percentage Closer Filtering (PCF) . . . . . . . . . . . . . 35 Cascaded soft shadow maps based on PCF filtering VII 2.3.3.2 Cascaded Shadow Maps (CSMs) . . . . . . . . . . . . . . 36 2.3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 2.4 Important issues in computing soft shadows . . . . . . . . . . . . . . . . . 38 2.4.1 Composition of multiple shadows . . . . . . . . . . . . . . . . . . . 38 2.4.2 Related work of physically based soft shadows . . . . . . . . . . . . 40 2.5 Conclusion . . . . . . . . . . . . . . . . . . . . . 41 3 Design, implementation, and results 42 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 43 3.2 Description of our cascaded soft shadow maps technique in real-time based on multiple PCF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.2.1 Cascaded Soft Shadow Maps algorithm . . . . . . . . . . . . . . . . 45 3.2.2 Frustum subdivision . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.2.2.1 Computing the shadow level . . . . . . . . . . . . . . . . . 47 3.2.3 Soft shadow approximation with sampling the area light source . . 48 3.2.3.1 From the rendering equation to soft shadow approximations 48 3.2.3.2 Area light source subdivision . . . . . . . . . . . . . . . . 50 3.2.4 Shadow map rendering . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.2.5 Assessing the Shadow Map Information . . . . . . . . . . . . . . . . 51 3.2.5.1 Assigning Shadow Map Contribution Weights . . . . . . . 51 3.2.5.2 Soft shadow visualization using n Shadow Maps . . . . . 51 3.2.5.3 Soft Shadow evaluation using Texture arrays . . . . . . . . 52 3.2.5.4 PCF filtering . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.3 Implementation . . . . . . . . . . . . . . . . . . . . . . . 53 3.4 Results and evaluation . . . . . . . . . . . . . . . . . . . . . . . 55 3.4.1 Visual results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Conclusions 67 |
| Type de document : | Mémoire master |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| MINF/586 | Mémoire master | bibliothèque sciences exactes | Consultable |
