Modern agriculture is facing a series of challenges to adopt new technologies to improve sustainability, profitability and resilience One of them is the use of robotic applications to assist or even replace manual workers for the complex task of interaction with the vegetation For example, harvesting and pruning are tasks that need certain dexterity to not only make the cuts, but also to move branches or foliage in the canopy to reach hidden objects or locations For such capability, first the robot should be able to perceive the vegetation and estimate the dynamics for the interaction This work mainly focuses on the perception problem, aiming to digitize commercial tree fruit canopies and estimating how it moves when force is applied to the branches We studied the suitability of two known algorithms, viz the space colonization and the Laplace based contraction algorithms, to build a geometric model of the tree using point cloud data from stereo cameras Such model is then used to estimate the dynamics of the tree, by considering the branches as links articulated by spring-damper joints The geometric model was evaluated for topological and morphological correctness by comparing it with the ground truth, obtaining better results with the Laplace based contraction algorithm Furthermore, results of the dynamics estimation showed that by adjusting the parameters for the spring-damper model, the motion prediction is promising, with a maximum mean squared error of 0073m in the tracking of the movement of the branches

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Visual 3D Reconstruction and Dynamic Simulation of Fruit Trees for Robotic Manipulation

Tree modelling is a necessary topic for discussion in virtual world construction. This paper presents a new approach that uses point cloud reconstructions of the resulting tree skeleton to form a compact parametric L-system expression after branching parameter abstraction. The proposed strategy can generate diverse new parametric L-system expressions under the control of several iterations, allowing the construction of a set of tree models with diverse growth patterns but more similar to real trees. This technique makes it possible to create large-scale tree models in virtual environments. 

3D Tree Modeling Based on Abstract Parametric L-System

A fast human–computer interaction dynamic modeling method for transmission towers based on space colonization algorithm is proposed in this paper. The 3D model of transmission towers can be generated only through the 3D coordinates of key points in CAD drawings. First, according to the coordinates of point calculate out the growth direction of the tower rod, and points are sampled along this direction, which are used as attraction points in the space colonization algorithm. The space colonization algorithm generates branches in the process of constructing the 3D skeleton of transmission towers. We give the convention relation between the attraction points and the branch nodes, forming a visual dynamic growth model of transmission towers by introducing interpolation time factor. The effectiveness of this method in the generation of transmission tower model is verified in the unity engine, and the model of a transmission tower which is higher than hundreds of meters is generated in seconds only by inputting the key coordinates in the human–computer interaction system of smart grid.

A Fast Human–Computer Interaction Dynamic Modeling Method for Transmission Tower in Power Systems

Tree modelling is a necessary topic for discussion in virtual world construction. This paper presents a new approach that uses point cloud reconstructions of the resulting tree skeleton to form a compact parametric L-system expression after branching parameter abstraction. The proposed strategy can generate diverse new parametric L-system expressions under the control of several iterations, allowing the construction of a set of tree models with diverse growth patterns but more similar to real trees. This technique makes it possible to create large-scale tree models in virtual environments.

Realistic tree modeling has been a subject of several studies but their application remains a computationally expensive task for real-time tree model generation. Space colonization algorithm [1] is one of such method which utilizes competition of space between tree branches to generate visually realistic trees and bushes. In this paper, we study the applicability of space colonization algorithm for real-time procedural tree model generation for video games. We present optimal parameters for space colonization algorithm, several approaches to introduce variety in the generated tree models such as procedural generation of unique crown shapes, several point sampling techniques and procedural generation of branch segments while maintaining the visual appeal and acceptable generation time.

Rafsan Ratul

Papers

Applicability of Space Colonization Algorithm for Real Time Tree Generation