Is it possible to obtain the volume of the tree canopy by measuring the projected shadow? This research proposes an innovative methodology with respect to the traditional method, although it is based on the same foundations. By combining the photogrammetric technique Structure from Motion (SfM), orthophotos and projected shadows, a more accurate and accessible method for calculating tree volume is proposed. Using scale models in controlled conditions, it is shown that by applying the well-known Thales Theorem, the height of the tree (one of the three semi-axes necessary to estimate the volume) can be inferred using the length of the shadow. The results show a minimum margin of error, which allows us to think about its possible implementation in precision agriculture, optimising resources and sustainability. This new methodology is not only accurate, but also shortens the working time on site, thus allowing to speed up the work within a tree plot.