3D-Landschaftsskizzen und Umweltvisualisierung

Computer-aided landscape visualization has emerged as a viable alternative to traditional representations and media, due to its ability to convey and transmit environment knowledge and development goals in a more direct and comprehensible fashion, especially for lay people. However, the available, photorealism-based computer graphics techniques suffer from limitations that prevent a wide acceptance in practice.The goal of this work has been the research and development of a set of novel computer graphics techniques for the automatic, GIS(Geographical Information Systems)-based visualization of vegetation, complex landscapes as well as environmental data. The core of the system are customizable three-dimensional, non-photorealistic real-time representations (interactive sketches). In contrast to conventional renderings, an interactive sketch should be capable of conveying a quickly understandable impression of a landscape from a walking perspective, as well as the selective focus on certain aspects, like factors of environment pollution.The choice of sketch as medium is not arbitrary: hand-drawn sketches have been traditionally the instrument of choice for landscape professionals. The computer graphics techniques developed in this work cope with traditional media and add the real-time capability, coherence as well as seamless control over abstraction degree and combination of different sketchy visual elements (contours and silhouettes, different leaf representations and sizes, hatch strokes, light and shadows) with photorealism. The user is thus able to control the rendering style by merely adjusting some parameters in a continuous space across both photorealism and different sketchy styles and interactively navigate through complex landscapes. The new visualization paradigm has been embedded into a landscape visualization software system, Lenne3D.User control has also been extended in another dimension: with suitable data structures (vegetation layers) it is possible to assign separate parameter sets to different parts of the scene and thus combine different rendering styles in the same view as needed (for example, current state of a landscape could be photorealistic and the planned state sketchy). Its also possible to change the style interactively during the navigation in the environment. This comes to address the identified needs for flexibility of potential users.One important benefit of sketchy landscape rendering is the possibility to map abstract data onto the landscape and incorporate it in the rendition. The control over the degree of abstraction makes it possible to obtain suitable rendering styles that leave enough place for additional data to be rendered in the same view. This feature has also been explored as it is of great interest in many application fields where data obtained from ecosystem simulation, measurements, etc. needs to be visualized in a meaningful fashion - related to the underlying landscape model.On a higher level, the newly developed algorithms should endorse the repertoire of landscapes planners and architects, as well as provide suitable media for planing and environment information communication. The system offers the required flexibility for the estimation and verification of the suitability of interactive sketches in practice

Real-Time Pen-and-Ink Illustration of Landscapes

Non-photorealistic rendering has been proven to be particularly efficient in conveying and transmitting selected visual information. Our paper presents a NPR rendering pipeline that supports pen-andink illustration for, but not limited to, complex landscape scenes in real time. This encompasses a simplification framework using clustering which enables new approaches to efficient and coherent rendering of stylized silhouettes, hatching and abstract shading. Silhouette stylization is performed in image-space. This avoids explicit computation of connected lines. Further, coherent hatching of the tree foliage is performed using an approximate view-dependent parameterization computed on-the-fly within the same simplification framework. All NPR algorithms are integrated with photorealistic rendering, allowing seamless transition and combination between a variety of photorealistic and non-photorealistic drawing styles

Real-Time Pen-and-Ink Illustration of Landscapes

Non-photorealistic rendering has been proven to be particularly efficient in conveying and transmitting selected visual information. Our paper presents a NPR rendering pipeline that supports pen-andink illustration for, but not limited to, complex landscape scenes in real time. This encompasses a simplification framework using clustering which enables new approaches to efficient and coherent rendering of stylized silhouettes, hatching and abstract shading. Silhouette stylization is performed in image-space. This avoids explicit computation of connected lines. Further, coherent hatching of the tree foliage is performed using an approximate view-dependent parameterization computed on-the-fly within the same simplification framework. All NPR algorithms are integrated with photorealistic rendering, allowing seamless transition and combination between a variety of photorealistic and non-photorealistic drawing styles

Realtime rendering of complex photorealistic landscapes using hybrid level-of-detail approaches

It still remains a challenge to realistically render outdoor scenes with interactive framerates since these scenes consist of a immense number of highly complex geometric models. A square kilometre of a forest incorporates millions of plants, hundreds of thousands of trees, and numerous small shrubs. Even the explicit storage of the plant positions i

Seamless Integration of Stylized Renditions in Computer-Generated Landscape Visualization

We propose enhancements and generalizations of 3D real-time computer visualization techniques used in landscape planning and architecture. As opposed to pure photorealism, illustration and non-photorealistic (NPR) techniques can be particularly efficient in conveying and transmitting selected visual information. By combining the power and accuracy of photorealistic models with the flexibility of abstract sketches, we have developed a flexible environment for the automatic creation of sketchy real-time rendering of landscapes. This allows for freedom of choosing the style and degree of abstraction of the visualization. All elements that contribute to the picture are seamlessly integrated and parameterized, including the transition from photorealism to non-photorealism. We expect a significant improvement of computer-aided landscape visualizations in our approach as such renditions are no longer limited to photorealism which often entails too much detail

Adaptive Billboard Clouds for Botanical Tree Models

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