waveform lidar - more than xyz point clouds
Post on 21-Jun-2015
549 Views
Preview:
DESCRIPTION
TRANSCRIPT
CONNECT. TRANSFORM. AUTOMATE.
WAVEFORM LIDAR - More than x,y,z pointclouds
Christian Sevcik, RIEGL Laser Measurement Systems GmbH Manager, Strategic Software Alliances
CONNECT. TRANSFORM. AUTOMATE.
Terrestrial Airborne Mobile Unmanned Industrial
CONNECT. TRANSFORM. AUTOMATE.
Dr. Andreas Ullrich, CTO Dr. Johannes Riegl, CEO
CONNECT. TRANSFORM. AUTOMATE.
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
CONNECT. TRANSFORM. AUTOMATE.
top related