Many users of LIDAR use discrete return systems for their production, however, many systems are capable of capturing the full waveform of the energy returned from an outgoing laser pulse. The figure illustrates a laser pulse directed through a tree. Different portions of the laser energy are backscattered/returned by various surfaces: branches, twigs, leaves, and hopefully the ground itself. In this example, the discrete return system recorded three returns, but a full waveform system would have recorded the continuous return of energy.
In Figure 1, the returns/echoes are represented by the rising peaks in the waveform. The peaks are the amplitude (intensity) of the object from which the laser pulse is reflected. Full waveform LIDAR systems digitize the entire backscattered laser pulse. This allows for a complete record of each received signal, resulting in more information about the returns, and the identification of possible additional returns.
One of the main advantages of waveform data is the ability to obtain additional information to produce dense detailed point clouds from the laser pulse. This is particularly useful for improving target resolution. Another advantage of waveform data is the capability to extract additional parameters about a return that may be used to help better automate the classification of the point cloud. Waveform data is generally higher in quality and resolution providing increased vegetation and ground detail. Some applications that utilize waveform include, but is by no means limited to, forestry and vegetation mapping, airport obstruction analysis, target detection, and habitat mapping.
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