## 3 Results and Case Study: UAV-Assisted Blast Design in a Basalt Quarry
### Blast Design Using 3D Geospatial Data  
A total of 30 blastholes were included in the designed blasthole pattern, with individual hole lengths ranging from 15.4 to 15.8 m. Figure 4 presents the parameters of two example blastholes, developed based on a 3D model of the selected quarry section. Thanks to the integration of an RTK module, each point in the 3D model is precisely georeferenced. This enables accurate determination of blasthole lengths while accounting for terrain irregularities, hole inclination, and orientation--with centimeter-level precision in reaching the target bench elevation (Figure 5). The designed blasthole pattern and the actual positions of the drilled holes are verified by importing drilling data from the HNS (Hole Navigation System) into the Strayos software, where the final burden verification is performed based on the true geometry of the executed pattern. Analysis of the burden geometry based on the 3D model enables a reliable calculation of actual burden values for each segment of the bench face. These values are obtained through photogrammetric evaluation using a fully three-dimensional visualization of the geometric dataset. As shown in Figure 6, the burden is defined as the shortest distance from the blasthole axis to the nearest point on the bench face, measured continuously along the entire bench height. In contrast to the conventional 2D burden measured in a single vertical plane perpendicular to the hole axis, the 3D burden provides a more accurate representation of local resistance to detonation by incorporating variations in face geometry along all spatial axes. This enhances the quality of blast assessments, particularly for charge placement optimization and flyrock risk reduction. Figure 4: Summary of blashhole parameters adjustable in the design phase using Strayos software. Figure 5: 3D model generated from photogrammetric data with a marked blashhole grid. Figure 6 presents the results of the spatial burden analysis, indicating that the minimum burden value required under the assumed safety criteria is 2.5 m. The vertical lines represent the positions of the blastholes, while the thin black horizontal lines correspond to burden lines at different elevation levels. Colored lines--red, green, and blue--highlight the locations on the bench face where the minimum burden occurs. In this case study, the 3D model revealed several areas where the burden fell below the safety threshold. Red zones represent areas with insufficient burden (<2.5 m), which significantly increase the risk of flyrock. Green zones denote adequately designed burden values (2.5-4.0 m), considered optimal for the given geological and operational conditions. Blue zones indicate excessive burden (>4.5 m), which may result in poor rock fragmentation and elevated seismic effects, especially near the toe of the bench. Access to detailed geospatial data allows blast designers to proactively revise layouts before drilling begins. In the execution phase, these data support the selection of appropriate explosives, charge masses, and configurations, matched to the actual burden in each blasthole. Figure 7 compares burden estimates derived from 3D and 2D analyses. In the 3D model, purple indicates areas with undersized burden, while blue denotes properly dimensioned regions. The 2D burden is illustrated as a black line through yellow reference points. Notably, hole No. 8 shows a partially detached rock fragment in the profile, an anomaly unlikely to be detected using traditional 2D laser scanning. Furthermore, the toe zone exhibits a significant discrepancy: the 2D burden value is more than double the actual 3D burden, emphasizing the risk of underestimating flyrock potential in conventional assessments. The most comprehensive assessment is achieved using a 3D burden heatmap, which visualizes actual burden values not just along individual hole profiles but across the entire blast area (Figure 8).