Living natural environments

By Quintijn Hendrickx

As a participant in the Challent program I’ve researched various topics related to the subject Living Worlds at the Computer Graphics and CAD/CAM group. Below are descriptions of the several topics I have studied.

Vegatation rendering (2011)

Rendering of organic objects is a challenging subject because of the complexity in the geometric structures. This complexity prevents us from applying the same rendering technique’s used for regular anorganic objects. Heavy use of LOD-technique’s and specific animation models are required to achieve realistic representations of vegatation while maintaining real-time performance.

During the last part of my challent program I will study different forms of vegetation rendering and implement a vegetation rendering system for osg.

A Graph-Based Composition Method for Rapid Shader Prototyping (2010)

Shader programming has become an increasingly important and complex task in computer graphics. As a result, several tools have been developed to assist developers in producing shader programs more efficiently and easily than writing them with traditional text-based editors. Graph-based composition tools have been proposed as an attractive alternative, as shader programs are intuitively represented as a graph structure. However, such tools do not usually exploit the structural and semantic information implicitly available in the graph to assist building, understanding and debugging shader programs.

We have worked on a graph-based composition method that allows developers to quickly and interactively prototype shader programs as networks of nodes. This method takes advantage of the graph hierarchical composition, allowing developers to design their shaders at various levels of abstraction, effectively promoting node reusability. Furthermore, consistently building upon the graph’s structure and semantics, the method significantly eases shader program debugging and provides very helpful insight into its workings, as demonstrated by the use and results of the open source prototype system implemented.

This method provides an efficient and very intuitive alternative for developing shaders. It is therefore particularly appropriate for novice shader programmers and students.

Based on this proposed method we have developed our own shader composition tool. Some screenshot of this tool are included below.

As a small case study we have used this shader tool to develop terrain shaders. Some images of the rendered terrain can be seen below.

Based on the developed shader modelling tool we have created a poster that provides a high level overview of the available features. It is available here.

Real-Time Rendering Of River Networks (2009 – 2010)

Rendering of water bodies such as rivers and oceans has proven to be one of the most dicult challenges in computer graphics. This work focuses on simulating flowing water in complex river networks with various kinds of junctions. Previous work includes several different kinds of particle systems [Yu et al. 2009] [Kipfer and Westermann 2006]. Particle systems are an intuitive approach for simulating water flow but often require large amounts of memory and computational power. We presents an ecient technique for real-time rendering of complex river networks without using any kind of particle system. Instead, Bézier curves and streaming normal maps are used to simulate the flow of water through rivers.

This work has been presented at the I3D 2010 conference for computer graphics in Washington DC. A pdf version of the presented poster can be downloaded here. A video of the demo showed at this conference can be viewed here.

The presented technique has been implemented as an extension to the OpenSceneGraph project osgOcean. This implementation can be downloaded as a rar file from here.