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WAVEFORM LIDAR - More than x,y,z pointclouds

Christian Sevcik, RIEGL Laser Measurement Systems GmbH Manager, Strategic Software Alliances

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Terrestrial Airborne Mobile Unmanned Industrial

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Dr. Andreas Ullrich, CTO Dr. Johannes Riegl, CEO

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WAVEFORM LIDAR

LIDAR technologies (Laser  RADAR,  ALS/TLS/MLS  )  

CW  Phase-­‐Based  LIDAR   Pulsed  Time-­‐Of-­‐Flight  LIDAR  

Discrete  Return  LIDAR   Echo-­‐DigiFzing  LIDAR  

Off-­‐Line    Full  Waveform  Analysis  

On-­‐Line    Waveform  Processing  

Time of flight - multitarget

t0 …Starttime Ps …pulse sent Pr …pulse reflected t1 …Endtime Pe …pulse echo Pr1…pulse reflected 1 Pr2…pulse reflected 2 Pr3…pulse reflected 3 Pr4…pulse reflected 4

Why waveforms ?

Plane target, nearly orthogonal measurement angle

Plane target, oblique measurement angle

Multiple reflection of the laser pulse (spatially distributed targets)

Target Laser pulse Echo

Multiple reflection of the laser pulse (equal distance targets)

Multiple reflection of the laser pulse (vertically stacked targets)

Waveform recording

Waveform processing methods

½ pulse

width ½

Waveform vs Discrete Return clear separation of target returns FWA: perfect result OWP: perfect result DRS: accurate results

merging of target returns FWA: perfect result OWP: satisfying result DRS: range error on second target

severe merging of target returns FWA: nearly perfect result OWP: just one target, but detection of pulse shape deviation DRS: just one target, no hint to second target

FWA .. Full Waveform Analysis OWP .. Online Waveform Processing DRS .. Discrete Return System

DRS

POINTCLOUD ATTRIBUTES

External Attributes

Native Attributes Geometry

What‘s in the Pointcloud?

Waveform pointcloud

Basic pointcloud

Calibrated amplitude

Grey scale encoding of point cloud: •  calibrated amplitude •  0 dB to 50 dB above detection threshold

Brightness decreases from near objects to far objects.

Reflectance

Grey scale encoding of point cloud: •  relative reflectance of target •  -20 dB to 3 dB with respect to diffusely reflecting white target

Brightness independent of object distance.

Targets with a reflectance above 3 dB are shown in white, targets below -20 dB are black.

Comparison intensity / reflectance

Range dependent intensity reading Range independent reflectance reading

Low High

Pulse shape deviation

!  deviation of echo pulse shape from emitted pulse shape δ, provided additional to target range and amplitude

!  Similarity of echo pulse (Pe) to instrument-specific reference pulse (Pr)

!  Measure for reliability of range result

N  …  the  number  of  digital  samples    si  …  digiFzed  echo  samples  pi  …  system  response  samples  

Pe

Pulse shape deviation

Pr1 Pr2 Pr3

Pr ‘best fit‘

Pulse shape deviation

All points Points filtered by pulse shape deviation Filtered pointcloud

Pulse shape deviation

All points pulse shape deviation > 20 marked yellow

WAVEFORM LIDAR IN FME

RDB Reader

!  Available since FME 2013 !  Supports Terrestrial, Mobile and Airborne RIEGL

scan projects (.rsp, .rpp)

RDB Reader

Workbench sample Calculate mean tree height

1. Read in RDB and reproject 2. Normalize height 3. Calculate Pointcloud statistics 4. Create 3D Tiles 5. Send to Shape File

Workbench sample Calculate mean tree height

Filter by pulse shape deviation

Workbench sample Calculate mean tree height

Raw LIDAR

Terrain model

Mean Tree Height

•  Additional pointcloud attributes •  Range independent intensity: REFLECTANCE •  Quality indicators for every single point

•  … and it is available in FME

Summary

Weight: 3.6kg Scan rate: 500000 meas/s Field of View: 330°

Planned integration of RIEGL VUX®-1 with Flying-Cam SARAH 3.0 ©

Latest developments

Thank You!

!  Questions?

!  For more information: !  Christian Sevcik, csevcik@riegl.com !  RIEGL Laser Measurement Systems GmbH

!  www.riegl.com !  www.riegllidar.com !  : RieglLMS

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