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Two canopy properties, leaf area index (LAI) and covered ground (CoverGnd), were estimated using hemispherical photography of three oak (Quercus pyrenaica) and eight pine (Pinus sylvestris) forest plots in Sierra de Guadarrama (central Spain). Pulses from airborne laser scanner (Lidar) that hit the surface on the exact location (within centimeter resolution) of the photographs were analyzed and separated by different radius size (from 0.5 to 20m). The correlation between Lidar and hemispherical photography estimates of canopy properties was highly significant, but was affected by the type of forest and the radius size. CoverGnd was better estimated using a small radius size (2.5m, equivalent to one fourth of canopy height), while LAI was better estimated using a larger radius size (7.5–12.5m, equivalent to the entire canopy height). In general, the smaller the tree, the shorter the radius was that must be used to …