International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
During autumn, when the deciduous trees are full of leaves, the
ground points detected from the discrete LIDAR pulses in the
mixed forest patch were 53139 points (1 pt/11.30 sq.m).
Whereas, by exploiting the full waveform return pulses, the
detection of ground point was increased by a little over 50 % to
80762 points (1pt/7.43sq.m). The accuracy validation test in the
earlier section has shown that the increase in ground penetration
due to the full waveform exploitation technique was able to
increase the vertical accuracy (Accuracy) of the DTM by 30
cm.
During winter, when most of the leaves of the deciduous trees
fall off, the detection of ground penetration increased
remarkably compared to the detection of ground penetration
during autumn. The ground points detected by using discrete
return pulses during winter, in the same patch of the mixed
forest, were remarkably high at 223938 points (1pt /2.68 sq.m)
Still, in winter, the full waveform return pulses increased the
detection of ground points by 20 % at 270142 points (1 pt/ 2.22
sq. m). However, the accuracy((Accuracy,)) validation test
shows that the vertical accuracy of the DTM obtained during
winter from both discrete LiDAR pulses and full waveform
LiDAR pulses were the same at around 0.40 m.
Figure 6 shows the DTM of the mixed forest hilly region. The
DTM constructed from the discrete return pulses obtained
during autumn was rough at places (red circle). However, by
using the full waveform return pulses, for the same,
considerable improvement in the smoothness and accuracy of
the bare ground model was achieved.
Full waveform return pulses (winter)
Figure 5. Comparing discrete and full waveform return
pulses
DTM constructed from discrete LIDAR during autumn
DTM constructed from full waveform LiDAR during winter
Figure 6. DTM of the study area
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