The use of tangible interfaces for navigation of landscape scenery -- for example, lost places re-created in 3D -- has been pursued and articulated as a promising, impactful application of interactive visualization. In this demonstration, we present a modern, low-cost implementation of a previously-realized multimodal gallery installation. Our demonstration centers upon the versatile usage of a smartphone for sensing, navigating, and (optionally) displaying element on a physical surface in tandem with a larger, more immersive display.

A Smartphone-Based Tangible Interaction Approach for Landscape Visualization

Interactive visualization of large forest scenes is challenging due to the large amount of geometric detail that needs to be generated and stored, particularly in scenarios with a moving observer such as forest walkthroughs or overflights. Here, we present a new method for large-scale procedural forest generation and visualization at interactive rates. We propose a hybrid approach by combining geometry-based and volumetric modelling techniques with gradually transitioning level of detail (LOD). Nearer trees are constructed using an extended particle flow algorithm, in which particle trails outline the tree ramification in an inverse direction, i.e. from the leaves towards the roots. Reduced geometric representation of a tree is obtained by subsampling the trails. For distant trees, a new volumetric rendering technique in pixel-space is introduced, which avoids geometry formation altogether and enables visualization of vast forest areas with millions of unique trees. We demonstrate that a GPU-based implementation of the proposed method provides interactive frame rates in forest overflight scenarios, where new trees are constructed and their LOD adjusted on the fly.

Interactive Large-Scale Procedural Forest Construction and Visualization Based on Particle Flow Simulation

We present a level of detail (LOD) method designed for tree branches. It can be combined with methods for processing tree foliage to facilitate navigation through large virtual forests. Starting from a skeletal representation of a tree, we fit polygon meshes of various densities to the skeleton while the mesh density is adjusted according to the required visual fidelity. For distant models, these branch meshes are gradually replaced with semi-transparent lines until the tree recedes to a few lines. Construction of these complete LOD models is guided by error metrics to ensure smooth transitions between adjacent LOD models. We then present an instancing technique for discrete LOD branch models, consisting of polygon meshes plus semi-transparent lines. Line models with different transparencies are instanced on the GPU by merging multiple tree samples into a single model. Our technique reduces the number of draw calls in GPU and increases rendering performance. Our experiments demonstrate that large-scale forest scenes can be rendered with excellent detail and shadows in real time. (Resume d'auteur)

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Tree Branch Level of Detail Models for Forest Navigation

Realistic and interactive visualization of individual trees is a desirable functionality in numerous applications for landscape planning, ecosystem simulations, and forest management. However, achieving a persuasive visualization of extensive forests while maintaining an interactive experience remains a challenge. This paper introduces a new framework for a convincing and interactive visualization of large-scale forests originating from forest growth simulation. First, the GPU-based self-organizing tree synthesis algorithm is adapted to produce detailed tree models on-the-fly with the desired level of detail and at interactive rates. Next, the algorithm is enhanced to generate tree models corresponding to the forest simulation results and local growth conditions. Finally, a forest succession model, based on single trees, is linked to the tree synthesis algorithm, to produce detailed tree models that concur with the results of forest simulation. The results demonstrate that the generated trees follow predicted height from forest simulation, are adapted to their neighbors properly, and retain the typical form of the corresponding species. A decimation technique, integrated directly into tree geometry construction, lowers memory requirements for interactive visualization of forests containing thousands of trees. Finally, a combination of the GPU-based tree synthesis and load balancing enables interactive tree synthesis in-between individual frames.

Interactive synthesis and visualization of self-organizing trees for large-scale forest succession simulation

Weaving Fire into Form: Aspirations for Tangible and Embodied Interaction

We present a framework for automatic Level-of-Detail control of botanical tree models based on hierarchical billboard clouds. These clouds react to quality measures developed specifically for plant models. They are optimized for providing minimum visual differences compared to the full polygonal models. The tree structure is analyzed to determine the geometric parts of the tree that are substituted by billboards. By computing the implicit surface of the tree model we can efficiently determine the average occlusion of each area within a tree that is used to guide the substitution. Our system is validated by comparing simplified versions of different trees with their full polygonal models. We realized our system as plug-in for MAXON CINEMA 4D.

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Adaptive Billboard Clouds for Botanical Tree Models

In 2004, a team of researchers realized a semi-immersive interactive gallery installation, visualizing an 1834 Mediterranean garden, introduced as "italienisches Kunststuck" (Italian legerdemain) by Peter Joseph Lenne. The park was originally realized on the grounds of Schloss Sanssouci in Potsdam, Germany. The installation centered on highly detailed renderings of hundreds of plants projected upon a panoramic display. Interactivity was expressed with a tangible interface which (while presently dated) we believe remains without near-precedent then or since. We present the installation (experienced by roughly 20,000 visitors), focusing on the interaction aspects. We introduce new book and table/door-format mockups. Drawing upon a heuristic of the scientist-philosopher Freeman Dyson, we consider grounded future prospect variations in the contexts of 2018, 2032, and 2202. We see this exercise as prospectively generalizing to a variety of similar and widely diverse application domains.

Philip Paar

Papers

A Smartphone-Based Tangible Interaction Approach for Landscape Visualization

Adaptive Billboard Clouds for Botanical Tree Models

An 1834 Mediterranean Garden in Berlin: Engaged from 2004, 2018, 2032, and 2202