Effects of Wind on Virtual Plants in Animation

Abstract

This paper presents the Growth-Flow method for animating the effect of wind on the motion and growth of virtual plant branches and leaves. The method incorporates changes to the growth rate when a plant is exposed to winds with speeds higher than a threshold. In particular, growth rate is reduced in branch elongation, increased in the branch radius, reduced in leaf length, and increased in leaf thickness. In addition, when a plant is exposed to wind for long time periods, the branch growth angle is changed to align more closely with the wind vector. The Growth-Flow method incorporates all these effects on growth and motion due to wind in one algorithm.

The Plani Plant Animation Framework

“…For example, to create an animation showing the effect of nutrients on plant growth, one could restrict the FUNCTION domain objects to Growth and Response to Stimulus [31]. Similarly, to create an animation showing the effect of wind on plant growth, one could restrict the FUNCTION domain objects to Growth and Locomotion [23]. If sufficient computer capacity to run all three objects of the FUNCTION domain (Growth, Locomotion, and Response to Stimulus), using real-time processing, then restrictions need not occur.…”

“…We selected the procedural approach because it provides the greatest flexibility for virtual plant variety with simple coding. In particular, objects in the FORM domain are generated using a nested L-System for each stem, petiole, and vein [23], the Leaf object is based on the radius variation formula [24], and the Fruit object is generated through the use of an ellipsoid formula. Examples of plants produced by the procedural approach are provided in Figure 8.…”

“…For example, there existed several plant animations for wind that included branches [25; 26; 27; 28], and leaves [22; 27]. In our implementation for the Stem object we used a current branch motion algorithm from Sakaguchi and Ohya and added to the algorithm to produce motion in the Petiole object [23], and Leaf object [24]. In addition to the Locomotion object, our implementation required the Growth object.…”

“…In addition to the Locomotion object, our implementation required the Growth object. Our growth algorithm generated a linear growth with the objective of considering a real-time animation rather than a frame-by-frame animation [23] which was generally based on the growth algorithm created by the Rodkaew et al paper [30].…”

Windy trees

“…In a recent work Derzaph and Hamilton [2013] introduced a model for capturing growth characteristics of simple tree models in relation to wind. Since it is intended for games, their method does not integrate a physically plausible wind model and their trees are modeled in a schematic and very limited way.…”