<p>Laser powder bed fusion (LPBF) Ti6Al4V holds broad application prospects in aerospace, biomedical and other fields due to its excellent strength-to-weight ratio and biocompatibility. However, the correlation between grain-scale deformation behavior and complex spatial geometry of <i>α</i> lamellae is not yet established. Micromechanical modeling often oversimplifies the microstructure, leading to simulation results that lack direct validation with experimental characterization. The present work aims to assess the predictive ability of quasi-3D model incorporating real surface microstructure and crystal plasticity constitutive law through comparison with high resolution digital image correlation (HR-DIC) measurements. Jointly, the effect of spatial orientation of <i>α</i> lamellae on deformation is assessed with models presenting varying spatial orientations. It is found that the quasi-3D model can statistically capture the heterogeneous strain field, whereas the predicted strain-localized regions only partially agree with the experimental characterization, with yet underestimated strain localization levels. The spatial orientation of <i>α</i> lamellae is found to significantly affect the plastic slip and hence the strain localization behavior, indicating that the spatial geometry of <i>α</i> grains cannot be ignored in crystal plasticity modeling when addressing the grain-scale deformation behaviors.</p>