Team Digiplante

Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: Scientific Foundations

Computer Graphics

The computer graphics in Digiplante inherits from the long tradition of AMAP works [54] , and is mostly conducted since 2004 in close partnership with the GreenLab team at LIAMA (Dr. ZHANG XiaoPeng and his students).

Simple plant LOD models and real time plant rendering

Principles and main research axis hold in the frame of the project :

Plant simulated visualization in DigiPlante project is still based on the AMAP prinicples [54] , characterized by a high level, device independant simulation output, called the line-tree. Geometrical ouput is a final process in the simulation stage, that can be processed or not. The Linetree structure describes a plant by a list of organs, refered by basic indetification information (organ type, age) and organ positioning in space 3D origin relative to seed position, and 3D orientation. Orientations (main direction, normal and secondary) are scalled, story thus internode diameter/length and other organ sizes. These geometrical informations are stored in a 3 by 4 mattrix, similar to a classical OpenGl Mattrix Model Viewer. This data structure shows several interests and drawbacks:

Scenes such as crops, forest, up to landscape visualisation was, up to now, mainly developped on a plant basis (not on a landscape use basis, as it is more and more the case in commercial products); and also without advanced dynamics, especially without plant/environment dynamics.

In the frame of the digiplante project, computer graphics development axis aims at developing new methods and approaches aiming to visualize large vegetation scenes in acceptable time (close to real time), in respect to plant structure and functioning. Prior is thus given to approaches keeping biological consistency (for instense leaf area) to appraoches keeping aesthetic aspects. Research axis do concern single plant LOD model definition, and new landscape simulation/visualisation approaches.

Single Plant LOD Models. :

Concerning single plant representation. In cooperation with LIAMA, we developped a set of algorithms dedicated to generate continuous LOD geometrical model from a Line tree and its associated hierarchical topology. The principles of the approach are the following:

Specific LOD shemes were also defined for coniferes, replacing graphical primitives (cylinders) by lines, and defining line set replacement patterns by simple lines on far trees.

An extensive summary paper covering many aspects developped in the past four years has been published by Wesley in Computer Anination and Virtual Words journal CAVW08

3D Reconstruction of tree crowns

This topic started two years ago at LIAMA, in the frame of the GreenLab project, with the objective to generate plant geometry from laser range point data. The work of PhD Zhu Cao is dedicated to the foliage crown. The proposed approach uses alpha shape (extension of voronoi diagrams). Originality of the approach lies in the automate definition of the alpha parameter (that controls the "smoothness" of the crown shape) , using a topological criteria: we want the surface to be a manifold. This approach, presented at Edutainment 08 [79] shows also a high interest on simulated plants, generating thus simplified shapes of crowns. 3D reconstruction from laser range point becomes a hot topic in forestry sciences. Both LIAMA GreenLab team and Digiplante were sollicited to participate to an ANR Bioenergy project "EMERGE", planning to evaluation wood ressource for energy (project is accepted and started begining 2009)