This paper proposes an HDRi-based data acquisition system to improve the quality of the Sky Component (SC) and the Exterior Reflected Component (ERC) in the daylight simulation model. The proposed system consists of an HDRi device equipped with shadow ring for high-frequency sky luminance capture and the HDRi-based gray card referencing procedure to measure the reflectances of surrounding structures. This system can provide timely updates of the exterior luminous environment for model-based real-time daylight control. Physical experiments with a test chamber were conducted to evaluate the performance of the prototypical system. In the experiments, HDRi techniques were applied to capture luminance distributions of the sky, window view and interior surfaces. Simulations of the indoor luminance distributions of the test chamber were conducted under two sets of daylight descriptions. The first simulation, derived from the concept of highly accurate image-based rendering, uses the HDRi daylight scene of the window view. The second simulation, the proposed method, uses a combination of the Tregenza sky derived from HDRi sky view and the model of the surrounding structures. Comparisons were made between both sets of simulations and the measured interior luminance levels. The RMSE and MBE were calculated using cells from the sub-divisions of the interior surface. The statistical analysis demonstrates that the proposed system in continuous operation can achieve a level of accuracy comparable to that of the image-based daylighting description from the window view. (C) 2014 Elsevier Ltd. All rights reserved.