Understanding strain localization in titanium and titanium alloys is central to depicting better how individual grains plastically deform and how grain orientation distribution, i.e., the local texture, affects the strain distribution within large regions of interest. High-resolution imaging over large fields of view is vital in detecting the nanometer-scale elementary and irreversible deformation mechanisms as a function of the variability of mesoscopic deformation inherited from the former millimeter-scale β-grains. High Resolution-Digital Image Correlation (HR-DIC) is used to assess quantitative deformation fields from the macroscopic to the microscopic scales. Moreover, HR-DIC is used to identify slip activity in the various polycrystalline Ti and Ti-alloys. Identification of slip systems was obtained using imaging from both scanning electron microscope (SEM) and laser scanning confocal microscope (LSCM). SEM provides a high spatial resolution in the surface plane, while LSCM micrographs provide out-of-plane measurements. Both imaging techniques are complementarily used to identify deformation slip and sliding at the sub-grain scale. In-situ HR-DIC under SEM paired with ex-situ LSCM and conventional SEM observations were used to identify three-dimensional surface strain localization and subsequently slip activity in the various Ti and Ti-alloys under tensile loading at room temperature. Interrupted tensile tests were performed to inform sliding evolution as a function of the applied plastic strain. Both in-plane and out-of-plane sliding displacement were evidenced at the sub-grain level leading to an increase in roughness with increasing applied plastic strain. Interestingly, former β-grains strongly affect both strain distribution and slip activity.