A Comprehensive Guide to Voxel and Object Structures

The GeoDict tutorial “A Comprehensive Guide to Voxel and Object Structures” offers a practical introduction to the fundamental components of digital structures in GeoDict. Using an example structure generated with GrainGeo, the tutorial explains how voxel function as the smallest volumetric units of a structure and how different materials and material properties can be assigned to them for subsequent simulations.

The focus is on the difference between individual voxel and GAD (GeoDict Analytical Data) objects. GAD objects such as spheres, ellipsoids, or fibers contain additional geometric information regarding size, position, and orientation, thereby enabling particularly flexible editing of the structure. The tutorial demonstrates how to select voxel and GAD objects, change materials, and scale, move, or delete entire objects. In addition, the tutorial explains the GAD status of a structure as well as the advantages of GAD objects when adapting the domain and rescaling structures without losing geometric information. The tutorial is intended specifically for new GeoDict users who want to learn about basic structure representation and its editing capabilities.

• Basics of Voxels and GeoDict Structures: Understanding the voxel-based structure of GeoDict structures, representing geometries using individual voxel, and assigning different material IDs and material properties for simulations.
• GAD Objects and Analytical Geometry Data: Introduction to GAD objects (GeoDict Analytical Data) such as spheres, ellipsoids, and fibers; use of stored geometric information such as size, position, and orientation; and understanding the advantages over pure voxel structures.
• GAD status and structural information: Interpretation of the GAD status in Project Status: Green for solid voxel fully described by GAD objects, yellow for a mixture of GAD objects and independent voxel, and red for structures without GAD information.
• Selecting and editing voxel: Selecting single or multiple voxel, displaying position and material ID, changing the material assignment of selected voxel, and editing contiguous components using Flood Fill.
• Selecting and editing GAD objects: Selecting complete GAD objects, identifying object ID and object type, and changing material, size, and orientation. In addition, selected objects can be deleted or regenerated based on their analytical description.
• Editing the domain: Adjusting the size of the computational domain, embedding existing structures in additional space, and fully restoring GAD objects previously truncated at the domain boundaries.
• Rescaling and increasing the resolution: Changing the voxel length and domain size to achieve higher structural resolution. Using the analytical information of the GAD objects, the structure can be rediscretized without losing the original geometric information.
• Practical application in GeoDict: Applying the various selection, editing, material, domain, and rescaling functions directly to a sample structure generated with GrainGeo.