Hierarkisk modellering og sanntidsvisualisering av skog

Abstract

This thesis introduces a method for fast rendering of a forest scenery in real-time. The subject of forest visualization has been an active research field in real-time rendering and this paper draws on the ideas and theory of previous work. The model that we employ is a hybrid of different techniques used in terrain visualization and the entertainment industry.

We can effectively divide this paper into two seperate parts. In the first part we concentrate on building a forest model by positioning trees in a landscape based on a quadtree. We show how to build an hierarchical structure by placing trees in such a manner that more trees are visible the further down the quadtree we traverse. Methods for placing different treetypes in the terrain and a dynamic memory scheme are also discussed.

The second part concentrates on the representation of trees in our model. We introduce a discrete Level-of-Detail method for effective visualization of thousands of trees by reducing the overall polygon-count. To save memory we also show how the information for a tree can be organized in an effective structure.

Since we are working within the bounds of real-time rendering, we finally show how to visualize our model. By using alfablending we can fade trees in and out of the landscape in such a fashion that we avoid popping artifacts. Finally we introduce how height values can be integrated into the our model.