TLSs use powerful highly collimated fairly optical light or laser light as sensing carrier. The energy of such a laser beam interacting with the measured object is partially reflected back in the direction of the laser system where it is registered by a sensor and used to measure the distance between this Inhibitors,Modulators,Libraries sensor and the illuminated spot on the measured object. This measurement can be achieved by detecting the Time Of Flight (TOF), by measuring the phase shift of an Amplitude Modulated Continuous Wave (AM-CW) or by Inhibitors,Modulators,Libraries using a Frequency Modulated Continuous Wave (FM-CW) technology . By providing a 3D image of its surrounding scene, TLS became a common tool in archeology, architecture and topography (e.g., ), but also in agriculture and forestry.
In forestry, TLS has been used to determine forest metrics such as the diameter at breast height (DBH), tree height, stem density, volume estimation, gap Inhibitors,Modulators,Libraries fraction, LAI and vertical plant profile [23�C25,20]. Inhibitors,Modulators,Libraries In agriculture, this device has been used to estimate the vegetative volume and its surface area [26,27].However, to get an accurate and precise description of the geometry of a small object as eg. a leaf, the number and density of the point cloud is determinant. In the case of scanned foliage, the scan quality could decrease because of:The shadow effect. The leaves on the TLS field of view foreground hide leaves on the background. Those are either partially scanned or not scanned at all . Thus, the number of point per leaves is reduced.The wind which may move the branches and the leaves during the scan process and decrease the quality of the scan.
The leaves reflectance, the geometric calibration of the TLS, the foliage distance and the TLS beam angle of incidence with the leave surface [34�C36] which could reduce the precision of GSK-3 the scanning.The fact that lasers are spherical range finders. That means that the distance between two points on a flat surface will increase with the distance to the beam aperture The light ambiance for large distance  as it avoid the sensor to record low reflectance.The ratios between the TLS beam footprint and the size of the scanned object, e.g., leaves . This footprint diameter depends on the TLS beam incidence angle with the leaves surface, the distance and the device features. The TLS beam footprint could overlap the scanned object.
In this case, the point cloud appears more like a set of ghost points or mixed pixels  and does not represent the object accurately and/or with precision.In conclusion, the point density for the foliage could be too sparse to provide detailed information to derive leaf inclination and clearly other geometric information such as area, shape or inclination. Traditionally, leaf inclination is directly determined with a protractor [39,40] or with an electromagnetic digitizer [41,42]. Those two methods are time consuming and labor intensive.