A dynamic 3D structural model is used to simulate the structural growth stages of a Scots pine canopy from age 5 to 50 years. The 3D structural output of the model agrees with observed measures of Scots pine canopy structure. Needles are added to the structural model according to measured density and phyllotaxy (distribution). The 3D structural models are used to drive both optical and microwave models of canopy radiometric response. Simulated canopy radiometric response is compared with airborne hyperspectral reflectance data (HyMAP) and airborne synthetic aperture radar (ASAR) backscatter data, recorded during the SAR and Hyperspectral Airborne Campaign (SHAC) conducted over the UK during 2000. Simulations are shown to agree well in general with observations. This method is shown to be suitable for exploring the impact of canopy structure on the measured remotely sensed signal.