StyleDEM: a Versatile Model for Authoring Terrains

Many terrain modelling methods have been proposed for the past decades, providing efficient and often interactive authoring tools. However, they generally do not include any notion of style, which is a critical aspect for designers in the entertainment industry. We introduce StyleDEM, a new generative adversarial network method for terrain synthesis and authoring, with a versatile toolbox of authoring methods with style. This method starts from an input sketch or an existing terrain. It outputs a terrain with features that can be authored using interactive brushes and enhanced with additional tools such as style manipulation or super-resolution. The strength of our approach resides in the versatility and interoperability of the toolbox

Desertscape Simulation

International audienceWe present an interactive aeolian simulation to author hot desert scenery. Wind is an important erosion agent in deserts which, despite its importance, has been neglected in computer graphics. Our framework overcomes this and allows generating a variety of sand dunes, including barchans, longitudinal and anchored dunes, and simulates abrasion which erodes bedrock and sculpts complex landforms. Given an input time varying high altitude wind field, we compute the wind field at the surface of the terrain according to the relief, and simulate the transport of sand blown by the wind. The user can interactively model complex desert landscapes, and control their evolution throughout time either by using a varietyof interactive brushes or by prescribing events along a user-defined time-line

Environmental Objects for Authoring Procedural Scenes

International audienceWe propose a novel approach for authoring large scenes with automatic enhancement of objects to create geometric decoration details such as snow cover, icicles, fallen leaves, grass tufts or even trash. We introduce environmental objects that extend an input object geometry with a set of procedural effects that defines how the object reacts to the environment, and by a set of scalar fields that defines the influence of the object over of the environment. The user controls the scene by modifying environmental variables, such as temperature or humidity fields. The scene definition is hierarchical: objects can be grouped and their behaviours can be set at each level of the hierarchy. Our per object definition allows us to optimize and accelerate the effects computation, which also enables us to generate large scenes with many geometric details at a very high level of detail. In our implementation, a complex urban scene of 10 000 m², represented with details of less than 1 cm, can be locally modified and entirely regenerated in a few seconds

Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion

International audienceAt large scale, landscapes result from the combination of two major processes: tectonics which generate the main relief through crust uplift, and weather which accounts for erosion. This paper presents the first method in computer graphics that combines uplift and hydraulic erosion to generate visually plausible terrains. Given a user-painted uplift map, we generate a stream graph over the entire domain embedding elevation information and stream flow. Our approach relies on the stream power equation introduced in geology for hydraulic erosion. By combining crust uplift and stream power erosion we generate large realistic terrains at a low computational cost. Finally, we convert this graph into a digital elevation model by blending landform feature kernels whose parameters are derived from the information in the graph. Our method gives high-level control over the large scale dendritic structures of the resulting river networks, watersheds, and mountains ridges

Modélisation de terrains par primitives

National audienceNous proposons un modèle de terrain hiérarchique et compact permettant de représenter des scènes complexes. Ce modèle de représentation s'inspire des surfaces implicites à squelettes et définit une fonction d'élévation sous la forme d'un arbre de construction. Les feuilles sont des primitives décrivant des morceaux de terrains à différentes échelles (montagnes, fleuves, ...) et les noeuds internes sont des opérateurs de combinaison. L'élévation d'un point est calculée en traversant la structure d'arbre et en combinant les contributions de chaque primitive. La définition des feuilles et des opérateurs garantit que la fonction d'élévation résultante est Lipschitzienne, ce qui permet d'accélérer les calculs de visualisation en utilisant un algorithme de sphere tracing. Mots Clés : modélisation de terrains, phénomènes naturels, modélisation procédurale, surface implicite We propose a compact hierarchical procedural model that combines feature-based primitives to create complex continuous terrains. Our model is inspired by skeletal implicit surfaces and defines the terrain elevation by using a construction tree whose leaves are primitives describing terrain fragments, and whose inner nodes include operations that combine its sub-trees. The elevation of a point is evaluated by traversing the tree and by combining the contributions of each primitive. The definition of both leaves and operators guarantees that the resulting elevation function is Lipschitz which enables us to speed up sphere tracing and surface adaptive tesselation algorithms

Génération procédurale de monde

In this thesis, we address the problem of automatic generation of graphical content with a high level of detail for the generation of worlds. In this quest for realism, the major scientific and technical challenges include: managing the mass of geometric data needed to create varieties of natural objects, taking into account interactions with the various objects and user control.Our approach is based on an original volumetric model for representing and unifying the different materials of land. We offer a range of high-level algorithms, combining simulation steps to ensure physical plausibility and visual realism, and procedural generation techniques to effectively manage complexity. Our algorithms are used to sculpt and complex terrain with caves and overhangs and generate roads with tunnels and bridges to cross natural barriers.Dans cette thèse, nous abordons le problème de la génération automatique de contenu graphique avec un haut niveau de détails pour la génération de mondes. Dans cette quête du réalisme, les principaux verrous scientifiques et techniques sont : la gestion des masses de données géométriques nécessaires à la création de variétés d'objets naturels, la prise en compte des interactions en les différents objets et le contrôle utilisateur.Notre approche s'appuie sur un modèle volumique original et unificateur permettant de représenter les différents matériaux d'un terrain. Nous proposons un ensemble d'algorithmes de haut niveau, combinant des étapes de simulation pour assurer la plausibilité physique et le réalisme visuel à des techniques de génération procédurale permettant de gérer efficacement la complexité. Nos algorithmes permettent ainsi de sculpter des terrains complexes avec des grottes ou des surplombs et de générer des routes avec des tunnels et des ponts permettant le franchissement d'obstacles naturels

Procedural generation of world

Dans cette thèse, nous abordons le problème de la génération automatique de contenu graphique avec un haut niveau de détails pour la génération de mondes. Dans cette quête du réalisme, les principaux verrous scientifiques et techniques sont : la gestion des masses de données géométriques nécessaires à la création de variétés d'objets naturels, la prise en compte des interactions en les différents objets et le contrôle utilisateur.Notre approche s'appuie sur un modèle volumique original et unificateur permettant de représenter les différents matériaux d'un terrain. Nous proposons un ensemble d'algorithmes de haut niveau, combinant des étapes de simulation pour assurer la plausibilité physique et le réalisme visuel à des techniques de génération procédurale permettant de gérer efficacement la complexité. Nos algorithmes permettent ainsi de sculpter des terrains complexes avec des grottes ou des surplombs et de générer des routes avec des tunnels et des ponts permettant le franchissement d'obstacles naturels.In this thesis, we address the problem of automatic generation of graphical content with a high level of detail for the generation of worlds. In this quest for realism, the major scientific and technical challenges include: managing the mass of geometric data needed to create varieties of natural objects, taking into account interactions with the various objects and user control.Our approach is based on an original volumetric model for representing and unifying the different materials of land. We offer a range of high-level algorithms, combining simulation steps to ensure physical plausibility and visual realism, and procedural generation techniques to effectively manage complexity. Our algorithms are used to sculpt and complex terrain with caves and overhangs and generate roads with tunnels and bridges to cross natural barriers

Visualisation and personalisation of multi-representations city models

City models have a wide variety of uses that require different kind of data representation or data models. Having a dynamic model that enables picking the right representations (meshes, volumetric data, point cloud, etc.) can prove useful to adapt an application to each user's needs. In this paper, we present an original method to create personalised visualisations of 3D city models on the fly. By organising the server data in a hierarchy of tiles, we are able to generate personalised models based on the user's preferences. These preferences take the shape of a set of rules that apply to each tile or city object and allow the user to choose which representation of the object to use depending on its position or semantic information (classification, height, etc.). Our method is designed around existing standards, guaranteeing the interoperability of the produced models

Visualisation and personalisation of multi-representations city models

International audienc