1.
www.merrick.com
Traditional Nadir Versus Oblique Perspectives
Presented to: AGIC
Presented on: August 31, 2022
Presented by: Matt Bethel, GISP
Director of Operations and Technology
with Merrick & Company
Airborne LiDAR
www.merrick.com

2.
Historical
Nadir Lidar
Perspective
Exaggerated along track
to show scan pattern

3.
Advancements
In LiDAR
Scanning
Dual Sensors
Single Sensor, Dual Scanners
Single Sensor, Dual Output Laser,
Single Scanner
Goals:
• Higher usable pulse rate
• Better point distribution

4.
Advancements
In LiDAR
Scanning
Intentionally not to scale
to show scan pattern

5.
Advancements
In LiDAR
Scanning
Intentionally not to scale
to show scan pattern

6.
6
If nadir airborne LiDAR scanning works well,
why consider oblique oriented collection?

7.
Nadir Collection Perspective

8.
Forward Facing Oblique Collection Perspective

9.
Rear Facing Oblique Collection Perspective

10.
Forward and Rear Facing Oblique Collections Perspective

11.
Nadir and Oblique LiDAR Scanner Types
Content courtesy of Riegl USA 2022

12.
Latest Generation Survey Grade Airborne LiDAR Scanner Types
Sensor Manufacturer Single Nadir Scanner Palmer Scanner Multiple Oblique Scanners
Fixed Wing Aircraft
Teledyne Optech Galaxy T2000 CZMIL SupeNova Galaxy G2
Riegl
VQ-780 II-S
VQ-580 II
VQ-480 II
VQ-880-G II VQ-1560 II-S
Leica Geosystems
TerrainMapper-2
Leica SPL-100
Chiroptera-5
VeriDaaS / L3Harris
Geiger Model LiDAR /
IntelliEarth
Helicopter and / or Unmanned Aircraft
Teledyne Optech
CL-90
CL-360
Riegl
VUX-1LR
VUX-1UAV
miniVUX-1LR
miniVUX-3UAV
VUX-240
miniVUX-1DL
VQ-840-G
VUX-120

13.
Palmer
Conical
LiDAR
Scanner
Video courtesy of L3Harris Corporation - Geiger-mode LiDAR Tech Talk ILMF 2015

14.
Project Boundary Project Boundary
1 2 1 2 1
2 4 2 4 2
1 2 3 2 3 2 3 2 1
2 4 6 4 6 4 6 4 2
Single Coverage Flight Plan Double Coverage Flight Plan (>50% sidelap)
LiDAR Sidelap Options
N
D

15.
Foliage
Penetration
From a
Dual Oblique,
55% Sidelap,
Fixed Wing
LiDAR Flight

16.
Point Density Comparisons
Content courtesy of Riegl USA 2022 Graphic courtesy of Leica Geosystem

17.
Data examples from a site flown
with all three types of LiDAR scanners
• Single nadir scanner
• Palmer conical scanner flown with double pass configuration (>50% sidelap)
• Dual oblique flown with double pass configuration (>50% sidelap)
Single and dual oblique scanners will be shown for comparison

18.
Single Nadir LiDAR

19.
Palmer Conical LiDAR

20.
Single Oblique LiDAR

21.
Dual Oblique LiDAR

22.
Single Nadir LiDAR Shadowing

23.
Palmer Conical LiDAR Shadowing

24.
Single Oblique LiDAR Shadowing

25.
Dual Oblique Single Pass LiDAR Shadowing

26.
Dual Oblique Double Pass LiDAR Shadowing

27.
Nadir LiDAR Above Ground Feature Modelling

28.
Palmer Conical LiDAR Above Ground Feature Modelling

29.
Dual Oblique LiDAR Above Ground Feature Modelling

30.
Power Line and Tower Modelling
Nadir LiDAR
Palmer Scanner LiDAR
Dual Oblique LiDAR

31.
Nadir LiDAR Above Ground Feature Modelling

32.
Palmer Conical LiDAR Above Ground Feature Modelling

33.
Dual Oblique LiDAR Above Ground Feature Modelling

34.
Scanner Type Summary
Nadir airborne scanning lidar
Cross hatched, semi-oblique
airborne scanning lidar
Palmer scanning oblique
airborne lidar
Great for Not ideal for Great for Not ideal for Great for Not ideal for
Open ground
modelling
Modelling the sides
of above ground
features
Open ground
modelling
Bathymetric
applications
Open ground
modelling
Ground modelling in
narrow urban
canyons
Foliage penetration
Bathymetric
applications
Modelling the sides
of above ground
features
Modelling the sides
of above ground
features
Foliage penetration
(depends on tree
type)
Ground modelling in
narrow urban
canyons
Ground modelling in
narrow urban
canyons
Bathymetric
applications
Dense foliage
penetration
Foliage penetration
(depends on tree
type)
Increasing point
density with two
laser and/or
detectors

35.
Thank You
• Matt Bethel
• Director of Operations and Technology
• Merrick & Company
• http://www.merrick.com/Geospatial
• matt.bethel@merrick.com