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The example below was generously provided by Christian Sevcik ofRiegl Laser Measurement Systems GmbHand was presented at the FME International User Conference in Vancouver in 2014.Please see the full presentation for a brief,but very clear,technical background on Waveform laser scans:http://www.亚搏在线safe.com/fmeuc/waveform-lidar-point-clouds/
Full-waveform LiDAR data differs from discrete LiDAR data because it considers the entire return as a continuous wave while the discrete data only considers the major peaks within the wave.Using a full wave results in a precise and attribute rich point cloud.This is in part due to the fact that waveform data contains additional attributes called amplitude,reflectance and pulse width and shape deviation.This additional information is especially helpful when dealing with more complex features like vegetation because they help to discriminate between the angles and details of the features.
FME is able to read waveform attributes from RIEGL Projects (RDB_PROJECT),RIEGL Laser Scan Database (RDB) and other LiDAR formats.The RDB_PROJECT and RDB reader support terrestrial,mobile,and airborne scanned projects which are in file formats .rsp and .rpp.
The purpose of this example is to demonstrate the use of LiDAR waveform attributes in FME through classifying point cloud data by tree height.The steps to do this are as follows:
The images below show how the data change throughout this 亚搏在线workflow example.Image a is the reprojected forest data (step 2).Image b shows the resulting tiled point clouds (step 11) after normalizing the elevation and filtering the points by pulse shape deviation.Image c shows the written shapefile output while image d shows the what the output would look like if being extruded by the z.mean.
a.b.
c.d.
Viewing and Inspecting Point Clouds
Converting Point Clouds to Surface Models without Classification
Profiling and Slicing Point Clouds
Getting Started with Point Clouds
Converting Point Clouds to Surface Models Using the PointCloudLASClassifier
What is a Point Cloud?What is LiDAR?
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