<i><span style="font-family:;" "="">Parkia biglobosa</span></i><span style="font-family:;" "=""> is a much-loved and over-exploited Afric...<i><span style="font-family:;" "="">Parkia biglobosa</span></i><span style="font-family:;" "=""> is a much-loved and over-exploited African savannah species for its socio-economic importance. Knowing and taking into account its architectural unit, which is the basis for diagnosing phenology, productivity and tree health, could provide a new perspective on its sustainable management. The aim of this study is to establish the architectural development in <i>Parkia biglobosa</i> by retrospective analysis. To achieve this objective, 390 individuals of all sizes ranging from seedlings to senescent trees were observed and analysed under various soil and climatic conditions in Côte d’Ivoire. The results showed that <i>Parkia biglobosa</i> is a light plant but shading tolerant. It is a mixed vegetative axis plant, the stem is orthotropic* in its proximal part and plagiotropic* (collapsing) in its distal part in young stage. The tree then transitions to an adult and old stage into a tree with a plagiotropic* axis in the proximal and distal parts, the trunk is built up by superimposing collapsed relay axes that gradually straighten, branching is sympodial*, growth is defined and sexuality is terminal and lateral. The ontogeny takes place in three phases: initiation of development and establishment of the crown (young), then flowering and establishment of the architectural unity (adult) and finally the death of secondary axes in the crown, duplication of the architecture by a series of partial and total reiterations (old). The level of organisation is 5: the phytomere, the module or growth unit, the axis, the architectural unit and the reiterated complex. Retrospective analysis of the modules showed that the dimensions of the growth units are indicators of morphological variation and species adaptation to a changing climate (<i>P</i> < 0.05). However, the equations generated by the morphological and habitat dimension linkage models are not significant (<i>R</i><sup>2</sup> and <i>r</i> </span><span style="font-family:;" "="">< 0.7) to be used as a guide for field data collection. This study represents an initiation into the architectural study of this species and the information provided will serve as a basis for further research into the architecture in relation to the sustainable use of this species.</span>展开更多
Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models fai...Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models faithful to botanical structure and development,not only representing the complex architecture of a real plant but also its functioning in interaction with its environment.Complex geometry and material of a large group of plants is a big burden even for high performances computers,and they often overwhelm the numerical calculation power and graphic rendering power.Thus,in order to accelerate the rendering speed of a group of plants,software techniques are often developed.In this paper,we focus on plant organs,i.e.leaves,flowers,fruits and inter-nodes.Our approach is a simplification process of all sparse organs at the same time,i.e.,Level of Detail(LOD),and multi-resolution models for plants.We do explain here the principle and construction of plant simplification.They are used to construct LOD and multi-resolution models of sparse organs and branches of big trees.These approaches take benefit from basic knowledge of plant architecture,clustering tree organs according to biological structures.We illustrate the potential of our approach on several big virtual plants for geometrical compression or LOD model definition.Finally we prove the efficiency of the proposed LOD models for realistic rendering with a virtual scene composed by 184 mature trees.展开更多
Vegetation ecosystem simulation and visualisation are challenging topics involving multidisciplinary aspects. In this paper, we present a new generic frame for the simulation of natural phenomena through manageable an...Vegetation ecosystem simulation and visualisation are challenging topics involving multidisciplinary aspects. In this paper, we present a new generic frame for the simulation of natural phenomena through manageable and interacting models. It focuses on the functional growth of large vegetal ecosystems, showing coherence for scales ranging from the individual plant to communities and with a particular attention to the effects of water resource competition between plants. The proposed approach is based on a model of plant growth in interaction with the environmental conditions. These are deduced from the climatic data (light, temperature, rainfall) and a model of soil hydrological budget. A set of layers is used to store the water resources and to build the interfaces between the environmental data and landscape components: temperature, rain, light, altitude, lakes, plant positions, biomass, cycles, etc. At the plant level, the simulation is performed for each individual by a structural-functional growth model, interacting with the plant's environment. Temperature is spatialised, changing according to altitude, and thus locally controls plant growth speed. The competition for water is based on a soil hydrological model taking into account rainfalls, water runoff, absorption, diffusion, percolation in soil. So far, the incoming light radiation is not studied in detail and is supposed constant. However, competition for light between plants is directly taken into account in the plant growth model. In our implementation, we propose a simple architecture for such a simulator and a simulation scheme to synchronise the water resource updating (on a temporal basis) and the plant growth cycles (determined by the sum of daily temperatures). The visualisation techniques are based on sets of layers, allowing both morphological and functional landscape views and providing interesting tools for ecosystem management. The implementation of the proposed frame leads to encouraging results that are presented and illustrate simple academic cases.展开更多
Global illumination effects are crucial for virtual plant rendering. Whereas real-time global illumination rendering of plants is impractical, ambient occlusion is an efficient alternative approximation. A tree model ...Global illumination effects are crucial for virtual plant rendering. Whereas real-time global illumination rendering of plants is impractical, ambient occlusion is an efficient alternative approximation. A tree model with millions of triangles is common, and the triangles can be considered as randomly distributed. The existing ambient occlusion methods fail to apply on such a type of object. In this paper, we present a new ambient occlusion method dedicated to real time plant rendering with limited user interaction. This method is a three-step ambient occlusion calculation framework which is suitable for a huge number of geometry objects distributed randomly in space. The complexity of the proposed algorithm is O(n), compared to the conventional methods with complexities of O(n^2). Furthermore, parameters in this method can be easily adjusted to achieve flexible ambient occlusion effects. With this ambient occlusion calculation method, we can manipulate plant models with millions of organs, as well as geometry objects with large number of randomly distributed components with affordable time, and with perceptual quality comparable to the previous ambient occlusion methods.展开更多
文摘<i><span style="font-family:;" "="">Parkia biglobosa</span></i><span style="font-family:;" "=""> is a much-loved and over-exploited African savannah species for its socio-economic importance. Knowing and taking into account its architectural unit, which is the basis for diagnosing phenology, productivity and tree health, could provide a new perspective on its sustainable management. The aim of this study is to establish the architectural development in <i>Parkia biglobosa</i> by retrospective analysis. To achieve this objective, 390 individuals of all sizes ranging from seedlings to senescent trees were observed and analysed under various soil and climatic conditions in Côte d’Ivoire. The results showed that <i>Parkia biglobosa</i> is a light plant but shading tolerant. It is a mixed vegetative axis plant, the stem is orthotropic* in its proximal part and plagiotropic* (collapsing) in its distal part in young stage. The tree then transitions to an adult and old stage into a tree with a plagiotropic* axis in the proximal and distal parts, the trunk is built up by superimposing collapsed relay axes that gradually straighten, branching is sympodial*, growth is defined and sexuality is terminal and lateral. The ontogeny takes place in three phases: initiation of development and establishment of the crown (young), then flowering and establishment of the architectural unity (adult) and finally the death of secondary axes in the crown, duplication of the architecture by a series of partial and total reiterations (old). The level of organisation is 5: the phytomere, the module or growth unit, the axis, the architectural unit and the reiterated complex. Retrospective analysis of the modules showed that the dimensions of the growth units are indicators of morphological variation and species adaptation to a changing climate (<i>P</i> < 0.05). However, the equations generated by the morphological and habitat dimension linkage models are not significant (<i>R</i><sup>2</sup> and <i>r</i> </span><span style="font-family:;" "="">< 0.7) to be used as a guide for field data collection. This study represents an initiation into the architectural study of this species and the information provided will serve as a basis for further research into the architecture in relation to the sustainable use of this species.</span>
基金This work is supported by National Natural Science Foundation of China projects No. 60073007, 60473110, 30371157 by National High-Tech Research and Development Plan of China under Grant No. 2006AA01Z301+1 种基金 by the French National Research Agency within project NATSIM ANR-05-MMSA-45 and by LIAMA funding with the project GreenLab.
文摘Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models faithful to botanical structure and development,not only representing the complex architecture of a real plant but also its functioning in interaction with its environment.Complex geometry and material of a large group of plants is a big burden even for high performances computers,and they often overwhelm the numerical calculation power and graphic rendering power.Thus,in order to accelerate the rendering speed of a group of plants,software techniques are often developed.In this paper,we focus on plant organs,i.e.leaves,flowers,fruits and inter-nodes.Our approach is a simplification process of all sparse organs at the same time,i.e.,Level of Detail(LOD),and multi-resolution models for plants.We do explain here the principle and construction of plant simplification.They are used to construct LOD and multi-resolution models of sparse organs and branches of big trees.These approaches take benefit from basic knowledge of plant architecture,clustering tree organs according to biological structures.We illustrate the potential of our approach on several big virtual plants for geometrical compression or LOD model definition.Finally we prove the efficiency of the proposed LOD models for realistic rendering with a virtual scene composed by 184 mature trees.
基金This work is supported by the National Natural Science Foundation of China under Grant No.60473110 and by LIAMAGREENLAB Project.
文摘Vegetation ecosystem simulation and visualisation are challenging topics involving multidisciplinary aspects. In this paper, we present a new generic frame for the simulation of natural phenomena through manageable and interacting models. It focuses on the functional growth of large vegetal ecosystems, showing coherence for scales ranging from the individual plant to communities and with a particular attention to the effects of water resource competition between plants. The proposed approach is based on a model of plant growth in interaction with the environmental conditions. These are deduced from the climatic data (light, temperature, rainfall) and a model of soil hydrological budget. A set of layers is used to store the water resources and to build the interfaces between the environmental data and landscape components: temperature, rain, light, altitude, lakes, plant positions, biomass, cycles, etc. At the plant level, the simulation is performed for each individual by a structural-functional growth model, interacting with the plant's environment. Temperature is spatialised, changing according to altitude, and thus locally controls plant growth speed. The competition for water is based on a soil hydrological model taking into account rainfalls, water runoff, absorption, diffusion, percolation in soil. So far, the incoming light radiation is not studied in detail and is supposed constant. However, competition for light between plants is directly taken into account in the plant growth model. In our implementation, we propose a simple architecture for such a simulator and a simulation scheme to synchronise the water resource updating (on a temporal basis) and the plant growth cycles (determined by the sum of daily temperatures). The visualisation techniques are based on sets of layers, allowing both morphological and functional landscape views and providing interesting tools for ecosystem management. The implementation of the proposed frame leads to encouraging results that are presented and illustrate simple academic cases.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.60073007 and 60473110)National High Technology Development 863 Program of China(Grant No.2006AA01Z301)LIAMA,and French National Research Agency(Grant No.NATSIM ANR-05-MMSA-45).
文摘Global illumination effects are crucial for virtual plant rendering. Whereas real-time global illumination rendering of plants is impractical, ambient occlusion is an efficient alternative approximation. A tree model with millions of triangles is common, and the triangles can be considered as randomly distributed. The existing ambient occlusion methods fail to apply on such a type of object. In this paper, we present a new ambient occlusion method dedicated to real time plant rendering with limited user interaction. This method is a three-step ambient occlusion calculation framework which is suitable for a huge number of geometry objects distributed randomly in space. The complexity of the proposed algorithm is O(n), compared to the conventional methods with complexities of O(n^2). Furthermore, parameters in this method can be easily adjusted to achieve flexible ambient occlusion effects. With this ambient occlusion calculation method, we can manipulate plant models with millions of organs, as well as geometry objects with large number of randomly distributed components with affordable time, and with perceptual quality comparable to the previous ambient occlusion methods.