This paper presents a novel physical modelling method to study projectile penetration problems. The method employs a recently developed transparent synthetic soil made of oil-saturated fused quartz, which represents the macroscopic behaviour of silica sand. Digital image correlation (DIC, also known as particle image velocimetry (PIV)) techniques were employed to quantify the response of granular soils to high-speed penetration, non-intrusively. A conical nose projectile made of steel was accelerated into a transparent soil target at an impact velocity of 13.6 m/s. Visualisation of the soil deformation was made possible by means of a novel seeded plane within the transparent soil model. The complete penetration event was recorded using a high-speed digital camera. The captured images were analysed using DIC, and further analysis of displacement trajectories and strains were also carried out using in-house algorithms.