In the example of Figure 9 the transmitted and received pulse were assumed as the step pulses and ToT is measured with the well defined point on leading edges. However, in actual practice the transmitted pulse is Gaussian while the shape of return pulse depends upon the geometry, reflectivity and surface roughness with the laser footprint ( a laser footprint is the area on ground which is illuminated by the laser pulse, due to its divergence and a finite size of the transmission aperture) on ground. Therefore, if is quite common that the return pulse may have a distorted, multimodal and depleted shape. To measure the ToT on this one needs to define a point corresponding to a point on the transmitted pulse. The following methods are used for this purpose.