Estimation of canopy gap fraction based on multi scanning data from terrestrial laser scanner

A terrestrial laser scanner can be used to measure canopy directional gap fraction distribution in forest stands. But some equipment only measure parts of gap fraction once on a time. A tilt mount of terrestrial laser scanner is able to enlarge the field of view of the scanner by scanning several times on the same position but with different tilt angles. Gap fraction were estimated from integration of the vertical and tilt mount of terrestrial laser scanner. Directional gap fraction distributions from hemispherical photographs were compared with distributions estimated from terrestrial laser scanner. The results showed that the directional gap fraction distributions from the two methods are similar.