Thank you for your detailed comments.
The pattern of waveforms is surprisingly random. Attached is the x-y-plot of Channel_2 data in this fragment.
Red dots are the first returns, green crosses are the coordinates of the discrete returns to which are
the waveforms linked in the las2txt output.
The scanner belongs to the Land-Board and they did the aquisition. They cannot comment the WF pattern.
> The position along the wave is given by:
> X = X0 + X(t)
> Y = Y0 + Y(t)
> Z = Z0 + Z(t)
> X0, Y0, Z0 are the position of the
There is the anchor point in the Pulsewave record but which is the anchor point and time 't' in the las2txt output of LAS_1.4 record?
The sample WF in my original posting is linked to the discrete return 4 of 4, first three discrete returns have no waveform.
There are pulses where WF segments are at the 2nd and 4th discrete returns of the same pulse.
# scale factor x y z 0.00025 0.00025 0.00025
# offset x y z 693333 6464372 192
695333.84 6464819.08 59.45 r=1 n=4 no_waveform
695333.89 6464819.02 57.26 r=2 n=4 no_waveform
695334.02 6464818.86 51.44 r=3 n=4 no_waveform
The returns r=1, 2, 3, 4 have the same GPS time 181652056.289710
695334.08 6464818.79 48.845 r=4 n=4 t=181652056.289710 X Y Z 181204044 dx=-3.35549e-06 dy=4.15178e-06 dz=0.000149762
> 181204044 :
W (2nd is the wavepacket offset)
Which offset this is? Is it the time offset (in picoseconds?) or the offset of the WF in bytes in the file?
X, Y, Z are the scaled and shifted coordinates of the discrete return,
offset x y z, scale factors, and X, Y, Z allow to calculate the position of discrete returns:
x_4 = X_offset + x_scale*X_4
y_4 = Y_offset + y_scale*Y_4
z_4 = Z_offset + z_scale*Z_4 : 192 + 0.00025*(-572620) = 48.845
But where is the first sample of the WF? Or the last sample?
Is the last sample of the WF linked to the last discrete return?
If the wavepacket offset is in time units then which is the start time?
If the wavepacket offset were in picoseconds then I got nonrealistic result for the offset in meters:
181204044(ps)*0.000149762(m/ps) = 27137.5 m!