Data

The data we used for the Vegetation Project will be available in the data/vegetation/tree_ref directory. The total data size is 3.3 MiB and is divided into two subdirectories:

1. tree_ref_sketchup (size: 3.2 MiB)

Contains the pre-processed tree models retrieved from the Sketchup 3D Warehouse in stl format. These models have been cleaned, normalized, and translated to the origin to ensure consistency across different tree shapes. They will be used to generate reference tree meshes at runtime using the CGAL 3D Alpha Wrapping algorithm.

Table 1. 3D models of pre-processed trees
tree conifer
tree ginkgo
tree quercus

A cleaned conifer (Cone tree)

A cleaned Ginkgo (Oval tree)

A cleaned Quercus (Round tree)

2. tree_ref_geo (size: 3.3 KiB)

Contains the Gmsh .geo files used to generate the LOD 0 reference tree (and trunk) meshes, here is an example of the Cone_tree_lod0.geo file:

SetFactory("OpenCASCADE");

// Define parameters
lc = 7;      // Characteristic mesh size
L = 0.7;        // Length of the trunk
R_base = 0.02;  // Radius of the trunk
R_ball = 0.3;   // Radius of the ball (foliage)
cone_height = 0.1; // Additional height for rounding the top
apex_radius = 0.01; // Radius at the apex for rounding

// Define the cone geometry (foliage)
Cone(2) = {0, 0, 0.2, 0, 0, L + cone_height, R_ball, apex_radius}; // Cone with rounded top

// Define physical groups
// Physical Volume("Trunk") = {1};  // Assigning a physical name to the trunk
Physical Volume("Foliage") = {2};  // Assigning a physical name to the cone

// Define the mesh size
Mesh.CharacteristicLengthMax = lc;
Mesh.CharacteristicLengthMin = lc/10;

The generated meshes are stored in the data/vegetation/tree_ref directory in .stl format (size: 153.6 KiB).

Table 2. 3D models of lod 0 trees and trunk
tree trunk
cone
oval
round

A trunk

A lod 0 cone tree

A lod 0 oval tree

A lod 0 round tree

Ultimatly, we would like to directly use the .geo files at runtime to avoid the need to store the tree meshes in memory. This will be part of our future work to optimize the memory usage and the overall performance of the Vegetation Project.

Next: Implementation Overview

References