Quantification of the interaction of a plant with its light-environment is pivotal in agricultural research. Three-dimensional (3-D) digitising and laser-scanning of field-grown tobacco plants were conducted and a realistic 3-D architectural model of a tobacco canopy was reconstructed. Spatial light distribution in the tobacco canopy was measured and this dataset was used to validate a 3-D canopy light distribution model based on Monte Carlo ray tracing. It was shown that the simulation results matched the measurement satisfactorily. High correlation between the field measurements and the simulation of light distribution in the tobacco canopy was reached (R²=0.99). The diurnal course of spatial light distribution in the tobacco canopy was simulated using the model. This work provides a foundation for quantifying 3-D radiation distribution and photosynthesis in the tobacco canopy as well as assessing tobacco ideotype using functional-structural plant models.