Although many simulation models of natural phenomena have been developed to date, little attention was given to a major contributor to the beauty of nature: the colorful patterns of flowers. We survey typical patterns and propose methods for simulating them inspired by the current understanding of the biology of floral patterning. The patterns are generated directly on geometric models of flowers, using different combinations of key mathematical models of morphogenesis: vascular patterning, positional information, reaction-diffusion, and random pattern generation. The integration of these models makes it possible to capture a wide range of the flower pigmentation patterns observed in nature.

Showy inflorescences - clusters of flowers - are a common feature of many plants, greatly contributing to their beauty. The large numbers of individual flowers (florets), arranged in space in a systematic manner, make inflorescences a natural target for procedural modeling. We present a suite of biologically motivated algorithms for modeling and animating the development of inflorescences with closely packed florets. These inflorescences share the following characteristics: (i) in their ensemble, the florets form a relatively smooth, often approximately planar surface; (ii) there are numerous collisions between petals of the same or adjacent florets; and (iii) the developmental stage and type of a floret may depend on its position within the inflorescence, with drastic or gradual differences. To model flat-topped branched inflorescences (corymbs and umbels), we propose a florets-first algorithm, in which the branching structure self-organizes to support florets in predetermined positions. This is an alternative to previous branching-first models, in which floret positions were determined by branch arrangement. To obtain realistic visualizations, we complement the algorithms that generate the inflorescence structure with an interactive method for modeling floret corollas (petal sets). The method supports corollas with both separate and fused petals. We illustrate our techniques with models from several plant families.

The hormone auxin plays a crucial role in plant morphogenesis. In the shoot apical meristem, the PIN-FORMED1 (PIN1) efflux carrier concentrates auxin into local maxima in the epidermis, which position incipient leaf or floral primordia. From these maxima, PIN1 transports auxin into internal tissues along emergent paths that pattern leaf and stem vasculature. In Arabidopsis thaliana, these functions are attributed to a single PIN1 protein. Using phylogenetic and gene synteny analysis we identified an angiosperm PIN clade sister to PIN1, here termed Sister-of-PIN1 (SoPIN1), which is present in all sampled angiosperms except for Brassicaceae, including Arabidopsis. Additionally, we identified a conserved duplication of PIN1 in the grasses: PIN1a and PIN1b. In Brachypodium distachyon, SoPIN1 is highly expressed in the epidermis and is consistently polarized toward regions of high expression of the DR5 auxin-signaling reporter, which suggests that SoPIN1 functions in the localization of new primordia. In contrast, PIN1a and PIN1b are highly expressed in internal tissues, suggesting a role in vascular patterning. PIN1b is expressed in broad regions spanning the space between new primordia and previously formed vasculature, suggesting a role in connecting new organs to auxin sinks in the older tissues. Within these regions, PIN1a forms narrow canals that likely pattern future veins. Using a computer model, we reproduced the observed spatio-temporal expression and localization patterns of these proteins by assuming that SoPIN1 is polarized up the auxin gradient, and PIN1a and PIN1b are polarized to different degrees with the auxin flux. Our results suggest that examination and modeling of PIN dynamics in plants outside of Brassicaceae will offer insights into auxin-driven patterning obscured by the loss of the SoPIN1 clade in Brassicaceae.

We present a method for generating realistic models of temperate-climate trees and shrubs. This method is based on the biological hypothesis that the form of a developing tree emerges from a self-organizing process dominated by the competition of buds and branches for light or space, and regulated by internal signaling mechanisms. Simulations of this process robustly generate a wide range of realistic trees and bushes. The generated forms can be controlled with a variety of interactive techniques, including procedural brushes, sketching, and editing operations such as pruning and bending of branches. We illustrate the usefulness and versatility of the proposed method with diverse tree models, forest scenes, animations of tree development, and examples of combined interactive-procedural tree modeling.

We introduce a class of biologically-motivated algorithms for generating leaf venation patterns. These algorithms simulate the interplay between three processes: (1) development of veins towards hormone (auxin) sources embedded in the leaf blade; (2) modification of the hormone source distribution by the proximity of veins; and (3) modification of both the vein pattern and source distribution by leaf growth. These processes are formulated in terms of iterative geometric operations on sets of points that represent vein nodes and auxin sources. In addition, a vein connection graph is maintained to determine vein widths. The effective implementation of the algorithms relies on the use of space subdivision (Voronoi diagrams) and time coherence between iteration steps. Depending on the specification details and parameters used, the algorithms can simulate many types of venation patterns, both open (tree-like) and closed (with loops). Applications of the presented algorithms include texture and detailed structure generation for image synthesis purposes, and modeling of morphogenetic processes in support of biological research.

The appearance of computer generated plants has improved significantly due to advances in both modeling and rendering. In this paper we describe a system that further improves the appearance of CG plants by including the tiny hairs that cover many plant organs. A plant skeleton is generated using an L-system and graphically interpreted using generalized cylinders. The individual hairs are then mapped onto the surfaces and boundary edges of the mesh. Hair properties are specified and adjusted according to positional information. Sample images included in the paper illustrate the impact of hairs on the appearance of rendered plants.

In contrast to the extensively researched modeling of plant architecture, the modeling of plant organs largely remains an open problem. We propose a method for modeling lobed leaves. This method extends the concept of sweeps to branched skeletons. The input of the model is a 2D leaf silhouette, which can be defined interactively or derived from a scanned leaf image. The algorithm computes the skeleton (medial axis) of the leaf and approximates it using spline curves interconnected into a branching structure (sticky splines). The leaf surface is then constructed by sweeping a generating curve along these splines. The orientation of the generating curve is adjusted to properly capture the shape of the leaf blade near the extremities and branching points of the skeleton, and to avoid self-intersections of the surface. The leaf model can be interactively modified by editing the shape of the silhouette and the skeleton. It can be further manipulated in 3D using functions that control turning, bending, and twisting of each lobe.

No abstract available.

Abstract Because of their complexity, plant models used in computer graphics are commonly created with proceduralmethods. A difficult problem is the user control of these models: a small number of parameters is insufficient tospecify plant characteristics in detail, while large numbers of parameters are tedious to manipulate and difficultto comprehend. To address this problem, we propose a method for managing parameters involved in plant modelmanipulation. Specifically, we introduce decomposition graphs as multiscale representations of plant structuresand present interactive tools for designing trees that operate on decomposition graphs. The supported operationsinclude browsing of the parameter space, editing of generalized parameters (scalars, functions, and branchingsystem silhouettes), and the definition of dependencies between parameters. We illustrate our method by creatingmodels of bonsai trees. Categories and Subject Descriptors (according to ACM CCS): I.3.6 [Computer Graphics]: Methodology and Techniques

Abstract We present a method for rendering 3D models in the traditionalline‐drawing style used in artistic and scientificillustrations. The goal is to suggest the 3D shape of the objectsusing a small number of lines drawn with carefullychosen line qualities. The system combines several known techniquesinto a simple yet effective non‐photorealisticline renderer. Feature edges related to the outline and interiorof a given 3D mesh are extracted, segmented, andsmoothed, yielding chains of lines with varying path, length, thickness,gaps, and enclosures. The paper includessample renderings obtained for a variety of models.

Summary form only given. We focus on dynamic geometric objects, which can be seen to develop over time. Examples include fractals, subdivision curves and surfaces, and models of growing biological structures. Coordinates and indices do not identify elements of these objects in a convenient, time-invariant way. For instance, the coordinates of a cell in a growing biological tissue may change over time, even though it materially is the same cell. Furthermore, if the cells are indexed, the indices may have to be updated following cell division in order to preserve consecutive numbering of the adjacent cells. Similarly, in the case of subdivision curves and surfaces, the existing points may change position over time, while the insertion of new points may require all points to be reindexed.

GeneVis provides a visual environment for exploring the dynamics of genetic regulatory networks. At present time, genetic regulation is the focus of intensive research worldwide, and computational aids are being called for to help in the research of factors that are difficult to observe directly. GeneVis provides a particle-based simulation of genetic networks and visualizes the process of this simulation as it occurs. Two dynamic visualization techniques are provided, a visualization of the movement of the regulatory proteins and a visualization of the relative concentrations of these proteins. Several interactive tools relate the dynamic visualizations to the underlying genetic network structure.

We integrate into plant models three elements of plant representation identified as important by artists: posture (manifested in curved stems and elongated leaves), gradual variation of features, and the progression of the drawing process from overall silhouette to local details. The resulting algorithms increase the visual realism of plant models by offering an intuitive control over plant form and supporting an interactive modeling process. The algorithms are united by the concept of expressing local attributes of plant architecture as functions of their location along the stems.

Implicit surface modeling systems have been used since the mid-1980's for the generation of cartoon like characters. Recently implicit models combined with constructive solid geometry (CSG) have been used to build engineering models with automatic blending. This work is built on a structured implicit modeling system which includes CSG, warping, 2D texture mapping and operations based on the BlobTree, and its application to the generation of a complex and visually accurate biological model of the sea shell Murex cabritii. Since the model is purely procedurally defined and does not rely on polygon mesh operations, it is resolution independent and can be rendered directly using ray tracing. An interface has been built to the BlobTree using an interpreted programming language (Python). The language interface readily allows a user to procedurally describe the shell based on numeric data taken from the actual object.

In this paper, we explore the problem of interactively mauipulating plant models without sacrificing their botanical accuracy.The primary technical contribution of the paper is a method for interactively manipulating plant structures using a inverse-kinematics optimizatitin technique.The branches of the plant are endowed with flexural and torsional stiffnesses, and these are used in the IK optimization.We demonstrate our approach with several examples of plant models arranged in this fashion.

Modeling and rendering of natural scenes with thousands of plants poses a number of problems. The terrain must be modeled and plants must be distributed throughout it in a realistic manner, reflecting the interactions of plants with each other and with their environment. Geometric models of individual plants, consistent with their positions within the ecosystem, must be synthesized to populate the scene. The scene, which may consist of billions of primitives, must be rendered efficiently while incorporating the subtleties of lighting in a natural environment. We have developed a system built around a pipeline of tools that address these tasks. The terrain is designed using an interactive graphical editor. Plant distribution is determined by hand (as one would do when designing a garden), by ecosystem simulation, or by a combination of both techniques. Given parametrized procedural models of individual plants, the geometric complexity of the scene is reduced by approximate instancing, in which similar plants, groups of plants, or plant organs are replaced by instances of representative objects before the scene is rendered. The paper includes examples of visually rich scenes synthesized using the system.

Interaction with the environment is a key factor affecting the development of plants and plant ecosystems. In this paper we introduce a modeling framework that makes it possible to simulate and visualize a wide range of interactions at the level of plant architecture. This framework extends the formalism of Lindenmayer systems with constructs needed to model bi-directional information exchange between plants and their environment. We illustrate the proposed framework with models and simulations that capture the development of tree branches limited by collisions, the colonizing growth of clonal plants competing for space in favorable areas, the interaction between roots competing for water in the soil, and the competition within and between trees for access to light. Computer animation and visualization techniques make it possible to better understand the modeled processes and lead to realistic images of plants within their environmental context. CR categories: F.4.2 [Mathematical Logi...

The paper extends Lindenmayer systems in a manner suitable for simulating the interaction between a developing plant and its environment. The formalism is illustrated by modeling the response of trees to pruning, which yields synthetic images of sculptured plants found in topiary gardens.

Rapid progress in the modeling of biological structures and simulation of their development has occurred over the last few years. It has been coupled with the visualization of simulation results, which has led to a better understanding of morphogenesis and given rise to new procedural techniques for realistic image synthesis. This paper reviews selected models of morphogenesis with a significant visual component.

This paper introduces a combined discrete/continuous model of plant development that integrates L-system-style productions and differential equations.The model is suitable for animating simulated developmental processes in a manner resembling time-lapse photography.The proposed technique is illustrated using several developmental models, including the flowering plants Campanula rapunculoides, Lychnis coronaria , and Hieracium umbellatum.

article Free Access Share on Modeling seashells Authors: Deborah R. Fowler Department of Computer Science, University of Calgary, and University of Regina Canada Department of Computer Science, University of Calgary, and University of Regina CanadaView Profile , Hans Meinhardt Max-Planck-Institut, fltrEntwicklungsbiologie 7400 Tttbingen,Germany Max-Planck-Institut, fltrEntwicklungsbiologie 7400 Tttbingen,GermanyView Profile , Przemyslaw Prusinkiewicz Department of Computer Science, University of Calgary, Alberta CanadaT2N 1N4 Department of Computer Science, University of Calgary, Alberta CanadaT2N 1N4View Profile Authors Info & Claims ACM SIGGRAPH Computer GraphicsVolume 26Issue 2July 1992 pp 379–387https://doi.org/10.1145/142920.134096Published:01 July 1992Publication History 91citation1,667DownloadsMetricsTotal Citations91Total Downloads1,667Last 12 Months273Last 6 weeks52 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Plant organs are often arrangedin spiratpatterns.This effwt is termed spiral phyllotaxis.Well known examples include the layout of seeds in a sunflower head and the arrangement of scales on a pineapple.l%is paper presents a method for modeling spiral phyllotaxis based on detecting and eliminating collisions between the organs while optimizing their packing.In contrast to geometric models previously used for computer graphics purposes, the new method arranges organs of varying sizes on arbitrarysurfaces of revolution.Consequently, it w be applied to synthesize a wide range of naturalplant structures. CR Categoriw 1.3.5 [ComputerGraphics]:

In this paper we present a method for modeling herbaceous plants, suitable for generating realistic plant images and animating developmental processes. The idea is to achieve realism by simulating mechanisms which control plant growth in nature. The developmental approach to the modeling of plant architecture is extended to the modeling of leaves and flowers. The method is expressed using the formalism of L-systems.

A new divisive algorithm for multidimensional data clustering is suggested. Based on the minimization of the sum-of-squared-errors, the proposed method produces much smaller quantization errors than the median-cut and mean-split algorithms. It is also observed that the solutions obtained from our algorithm are close to the local optimal ones derived by the k-means iterative procedure.