Based on the algorithm of an volumetric particle streak velocimetry (VPSV) developed, two digital cameras in an angular oriented configuration were used to simultaneously capture two images of seeding particles in the same space of interest in a full-scale room. The room airflow was seeded with helium-filled soap bubbles of neutral buoyancy. The 5.5×3.7×2.4 m (W×D×H) test room was constructed within a large air-conditioned room ventilation simulator (RVS) to simulate and monitor indoor air environment. Two banks of projector lamps were used for volume illumination. The VPSV algorithm and the measurement accuracy of the system were evaluated using six rulers as stationary streaks in the test room. Three ventilation cases at different air change rates were tested using the system and three-dimensional airflow velocity maps are presented in this paper. This VPSV system offers a promising method to measure 3-dimensional airflow in full-scale rooms of commercial, industrial, agricultural buildings and other confinement airspaces such as transportation vehicles.