# Voxel-Based Digital Twin Framework for Earthwork Construction
## 4 Implementation of the Proposed System
### Graphical Simulation Environment for Model-Equipment Interaction
#### 4.1.3 Model Integration in Platform
Additionally, scans achieved through laser scanners and UAVs are sometimes incomplete due to limited data capturing, occlusions, or incorporate uncertainties due to the subsampling to optimize computation for computer analysis. These can additionally affect the quality of the voxel-based construction models. Hybrid data collection methods, such as cameras and laser scanning from multiple locations, will advance operational data collection. Additionally, sensor technologies integrated with construction equipment can significantly enhance the equipment's behavior. Integrating the method with interface technologies such as machine guidance, augmented reality, and virtual reality can advance the systems by providing a more granular and detailed work environment using voxels, helping stakeholders with rich information, facilitating decision-making, and leading to improved productivity, work quality, and safety. In our proposed system, the size of the voxel can be changed according to site condition and required accuracy can be achieved (for example, smaller voxels can be used to represent the inhomogeneous ground conditions or represent detailed features of the design models); however, this increases the number of data points, leading to significant computational and storage demands. This creates a trade-off between accuracy and efficiency, which may limit the scalability of the framework, especially for large-scale earthwork projects, unless optimized voxelization and storage techniques are applied. Efficient voxels and cloud-based storage could be explored to enhance scalability. Moreover, the mode-equipment interaction is driven by geometric and rule-based methods rather than simulation-based, such as FEM or DEM [39]. Future integration with physics-realistic simulation engines could enhance predictive capabilities. Additionally, the system was implemented in Unity 3D, where physics properties such as colliders were assigned; this approach has system limitations [51; 52]. The current proposed system provides efficient visualization in an integrated environment and updates the system when new data is available. However, in the current state, it serves as a monitoring, visualization, and analysis tool, providing design and construction information at any stage. Advanced analysis, such as predictive or prescriptive analysis, is not supported, which can significantly improve decision support and achieve a more proactive system [53]. The proposed framework serves as a foundation for the advancement in the field of automated earthwork construction monitoring techniques and model-equipment interaction. These applications are not limited to surface excavation, but can also greatly support deep excavation and underground excavation, such as drill-and-blast construction [54]. Currently, the system is applied and validated through two common and representative cases, namely, building pad and trench excavation. Additional validation is needed for more complex and specialized earthwork construction. Each scenario presents specific and unique challenges that need to be explored, such as voxel resolution, data integration, and visualization strategies. **Author Contributions:** Conceptualization, M.S.K. and J.S. ; methodology, M.S.K., H.S.C. and J.S. ; software, M.S.K. ; validation, M.S.K., H.S.C. and J.S. ; formal analysis, M.S.K. ; investigation, M.S.K., H.S.C. and J.S. ; resources, J.S. ; data curation, M.S.K. H.S.C., and J.S. ; writing--original draft preparation, M.S.K. ; writing--review and editing, M.S.K., H.S.C. and J.S. ; visualization, M.S.K. ; supervision, J.S. ; project administration, J.S. ; funding acquisition, J.S. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MEST), grant number RS-2024-00356995, and the Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure, and Transport, grant number RS-2020-KA157089.