Interactive Vegetation Rendering with Slicing and Blending

Detailed and interactive 3D rendering of vegetation is one of the challenges of traditional polygon-oriented computer graphics, due to large geometric complexity even of simple plants. In this paper we introduce a simplified image-based rendering approach based solely on alpha-blended textured polygons. The simplification is based on the limitations of human perception of complex geometry. Our approach renders dozens of detailed trees in real-time with off-the-shelf hardware, while providing significantly improved image quality over existing real-time techniques. The method is based on using ordinary mesh-based rendering for the solid parts of a tree, its trunk and limbs. The sparse parts of a tree, its twigs and leaves, are instead represented with a set of slices, an image-based representation. A slice is a planar layer, represented with an ordinary alpha or color-keyed texture; a set of parallel slices is a slicing. Rendering from an arbitrary viewpoint in a 360 degree circle around the center of a tree is achieved by blending between the nearest two slicings. In our implementation, only 6 slicings with 5 slices each are sufficient to visualize a tree for a moving or stationary observer with the perceptually similar quality as the original model

GENERATION OF FORESTS ON TERRAIN WITH DYNAMIC LIGHTING AND SHADOWING

The purpose of this research project is to exhibit an efficient method of creating dynamic lighting and shadowing for the generation of forests on terrain. In this research project, I use textures which contain images of trees from a bird’s eye view in order to create a high scale forest. Furthermore, by manipulating the transparency and color of the textures according to the algorithmic calculations of light and shadow on terrain, I provide the functionality of dynamic lighting and shadowing. Finally, by analyzing the OpenGL pipeline, I design my code in order to allow efficient rendering of the forest

A Tool for the Creation and management of level-of-detail models for 3D applications

Real-time visualization of 3D scenes is a very important feature of many computer graphics solutions. Current environments require complex scenes which contain an increasing number of objects composed of thousands or even millions of polygons. Nevertheless, this complexity poses a problem for achieving interactive rendering. Among the possible solutions, stripification, simplification and level of detail techniques are very common approaches to reduce the rendering cost. In this paper, we present set of techniques which have been developed for offering higher performance when rendering 3D models in real-time applications. Furthermore, we also present a standalone application useful to quickly simplify and generate multiresolution models for arbitrary geometry and for tree

Multiresolution Foliage Rendering

Ponència presentada en CoSECiVi 2020, VI Congreso de la Sociedad Española para las Ciencias del Videojuego On-line, 7-8 d'octubre de 2020.This work presents a continuous level of detail representation of foliage of trees. Multiresolution modeling allows to adapt the number of polygons to render to the relevance of the object in the scene. However, foliage is represented by isolated polygons, so most of the multiresolution modeling methods do not work properly with this part of the tree. This paper presents a multiresolution model that allows to adapt the number of leaves to the relevance of the foliage in the scene. The criterion to select the appropriate leaves to render is based on a previously performed view-driven simplification. To adapt this parameter in real time, data structures and the necessary algorithms that allow us to extract the appropriate number of polygons are presented. Some tests have been developed to evaluate the proposed solution and results show the good performance of the presented continuous level of detail

Extracting More Data from LiDAR in Forested Areas by Analyzing Waveform Shape

Light Detection And Ranging (LiDAR) in forested areas is used for constructing Digital Terrain Models (DTMs), estimating biomass carbon and timber volume and estimating foliage distribution as an indicator of tree growth and health. All of these purposes are hindered by the inability to distinguish the source of returns as foliage, stems, understorey and the ground except by their relative positions. The ability to separate these returns would improve all analyses significantly. Furthermore, waveform metrics providing information on foliage density could improve forest health and growth estimates. In this study, the potential to use waveform LiDAR was investigated. Aerial waveform LiDAR data were acquired for a New Zealand radiata pine plantation forest, and Leaf Area Density (LAD) was measured in the field. Waveform peaks with a good signal-to-noise ratio were analyzed and each described with a Gaussian peak height, half-height width, and an exponential decay constant. All parameters varied substantially across all surface types, ruling out the potential to determine source characteristics for individual returns, particularly those with a lower signal-to-noise ratio. However, pulses on the ground on average had a greater intensity, decay constant and a narrower peak than returns from coniferous foliage. When spatially averaged, canopy foliage density (measured as LAD) varied significantly, and was found to be most highly correlated with the volume-average exponential decay rate. A simple model based on the Beer-Lambert law is proposed to explain this relationship, and proposes waveform decay rates as a new metric that is less affected by shadowing than intensity-based metrics. This correlation began to fail when peaks with poorer curve fits were included