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Creating Value …
… Delivering Solutions
Aerial and Mobile LiDAR Data Fusion
Dr. Srini Dharmapuri, CP, PMP
What You Will Learn About LiDAR Fusion
Mobile and Aerial LiDAR
Technology Components & Parameters
Project Lifecycle
Vertical Products
Fusion of Mobile and Aerial LiDAR Data
Compatibility and Challenges
Fusion Workflow
Fusion Sample
Benefits of Data Fusion
Light Detection and Ranging (LiDAR)
Proven technology in deriving elevation information
Elevation is one of the FGDC Core Framework data
layers as a foundation for GIS solutions
Two general types of LiDAR collection:
Aerial
Fixed wing platform (aircraft) and
Rotary platform (helicopter)
Terrestrial
Road vehicle, all terrain vehicle,
Boat, barge and
Stationary tripod
Mobile and Aerial LiDAR
Aerial LiDAR
Optech Gemini
Mobile LiDAR
Optech Lynx
LiDAR Project Life Cycle
Phase Mobile LiDAR Aerial LiDAR
Scope Development
LiDAR Data Collection
LiDAR Data Pre-processing
LiDAR Data Processing
Product Generation
• Mission Plan to Cover the Project Area • Access & Logistics • Geodetic Control Validation
• System Calibration • Data Collection
• Filtering/Classification • Planimetric Data Capture
• Filtering/Classification • Intensity Images • LiDARgrammetry
• Geocoding of LiDAR data • Geometric Correction of LiDAR data • Projection Transformation
• Elevation: Grid generation / TIN / Contours
• Supplemental & Derived
LiDAR Vertical Products
Aerial LiDAR Bare Earth /
Digital Elevation Models
TIN/Contours
Cross-Sections/Profiles
Intensity Images
Volume Calculations
Breaklines for hydro
flattening.
Mobile LiDAR Bare Earth/
Digital Elevation Models
TIN/Contours
Cross-Sections/Profiles
Intensity Images
Volume Calculations
Planimetrics
Centerline
Shoulders
Edge of Pavement
Median barrier
Pavement Striping
Mobile LiDAR Supplemental Products
- Color gradation denotes elevation - Dashed lines depict Track corridor
Assets
Pavement marking,
Roadside obstacles,
signs, street lighting
Roadway Inventory
Bridges, Approaches,
Drive away, Lane,
Median, Rail crossings
Railway Applications
Right of way, Vegetation
encroachment.
First Floor Elevation
Geo-referenced Side-view
images for verification and
potentially QA/QC.
Mobile LiDAR
Mobile LiDAR Components & Parameters
Parameters Elevation Accuracy Around 5cm
Field of View 360°
Pulse Repetition Frequency
50, 100 or 200 KHz
Area Coverage Limited. For Corridor Applications
Returns per Shot 4 (1st, 2nd, 3rd, Last)
Range 200m (corridor varies)
Components Laser Sensor Range Information
GPS Precise Position Information
Inertial Measurement Unit
(IMU)
Attitude Information
Distance Measurement
Instrument (DMI)
To Assist IMU incase of GPS Outage
Mobile LiDAR “Instrument”
Mobile LiDAR: Dual Sensor System
Minimize Laser Shadowing
Optimize Field of View
(FOV)
Sensor will see everything
behind the vehicle
Sensor will see ~35º in front of
vehicle
Full 360º area coverage
All sides captured
Sensor arrangement facilitates
effective corridor mapping
Mobile LiDAR: Mission Planning Key Terms
DEM Post
Spacing
Pulse Repetition
Frequency
Scan Frequency
Drive Speed
Range
Expected
Vertical
Accuracy
Control Points
Check Points
Control Points
Data Collection Path
Mobile LiDAR Products
Standard point-cloud with elevation/intensity display
"Colorized" point-cloud
Mobile LiDAR Products
Mobile LiDAR Products
Mobile LiDAR Products
Advantages of Mobile LiDAR
Everything is Captured
Inundate the site with high-density scan information
Operational Efficiencies
Collect day or night and around localized weather events
Large project areas collected faster than traditional
surveys
Minimize or Eliminate notices for Right of Entry
Quality Deliverables
Complete scenes, not just lines and points
Ability to look at from many angles and aspects
High-precision promotes Change Detection
Repeatable results allow for seamless integration with
past surveys
Cost Effective
Aerial LiDAR
Aerial LiDAR Components and Parameters
Parameters Elevation Accuracy Variable. 12cm or above is
Standard Field of View 0-50°
Pulse Repetition Frequency
150 or above
Area Coverage Broad
Returns per Shot 4 (1st, 2nd, 3rd, Last)
Operational Altitude 1500m – 6500m
Components Laser Sensor Range Information
Airborne GPS Precise Position Information
Inertial Measurement Unit
(IMU)
Attitude Information
Aerial LiDAR: Flight Planning Parameters
Scanner System
(relates to beam
pattern)
Flight Altitude
(if flight limitations
exist)
Pulse Repetition
Frequency (PRF)
Scan Frequencies
Scan Angle (FOV) -
possible max FEMA 40°,
USGS suggests 34°
Aerial LiDAR Sample
Clipped to area of interest
Advantages of Aerial LiDAR
Day or night operation.
Efficient acquisition of millions of points per minute.
Capture multiple returns per pulse including intensity
information.
Fast data processing providing rapid turnaround.
Large data sets with many possible products.
Accuracy.
LiDAR Fusion
LiDAR Fusion
Mobile and Aerial LiDAR technologies have been
deployed independently towards generating elevation
information.
The technologies are complimentary.
The accuracies are comparable (in the big picture
perspective)
Similar products derived from both the technologies.
The data storage format is the same:
ASPRS .las format
Sensor 1 Sensor 2 Fusion
Signal Level
Pixel Level
Signal Fusion - Pixel
Transformation - Feature Extraction - Decision Making
Signal Level
Pixel Level Pixel Level Fusion- Feature Extraction -
Decision Making
Feature Level
Decision Level
Feature Fusion - Decision Making
Feature Level
Decision Level
Decision Fusion
LiDAR Fusion: Remote Sensing Perspective
LiDAR Fusion: Issues and Challenges
The Aerial LiDAR is “Nadir; Vertical Down” and
Mobile LiDAR is “Side Looking”
The project life cycle is nearly same for both
Aerial and Mobile LiDAR data
By fusing Aerial LiDAR data with Mobile LiDAR (base layer), we
get more information than can be obtained from a single dataset
Technology Accuracy Resolution Volume Point
Density Area
Coverage Primary
Aerial Variable 15 cm
1 m 167,000 pts/sec
1-10 / Sq meter
Variable Topo Products
Mobile 5 cm 1-4 cm 400,000 pts/sec
+200 / Sq meter
400 miles/day
Survey Grade
LiDAR Fusion: Work Flow
Use the Same Base Station to Process Aerial and Mobile LiDAR Data
The Same Control will be used to Constrain Aerial and Mobile LiDAR Data
Geocode & Geometric Correction of Aerial LiDAR Data
Conflate Aerial LiDAR with Mobile LiDAR
Fuse into a Single Dataset
Geocode & Geometric Correction of Mobile LiDAR Data
LiDAR Fusion Sample
Fusion: Mobile LiDAR Collection
Fusion: Clipped Area
Fusion: Mobile with Aerial Supplement
Fusion: Combined Mobile and Aerial Points
Fusion: Contours with Ortho Image
Keystone Corridor
LiDAR Sensor
IMU
GPS
Camera
Mobile LiDAR
Mobile LiDAR
Project Area – LiDAR Scanning
105 Miles
Captured over 4-day Period
Collection Swath
Custom Mounting
Ground Control
Utilized to Constrain LiDAR Data
Enhances Overall Accuracy
Established via GPS RTK / Total Station
Captured at “LiDAR Identifiable” Objects:
Top-of-Rail
Station Platform Corners
Base of Catenary Structures
Data Fusion
Merging of Data
Aerial LiDAR
Mobile LiDAR
Value:
Single Dataset
Scene Comprehension
Common Accuracy
Minimizes Shadowing
Spatial Extent
LiDAR Fusion Benefits
The Best of Each Capture Technique
Mobile LiDAR (Side-look)
Provides high density micro-level data
Data acquisition efforts are minimal compared
to Aerial LiDAR
Captures underpass and under canopy
Low cloud will be not hinder data collection
Everything is captured and so data is useful in
Assets mapping, roadway inventory, pavement
condition, intersection studies.
Tall hard breaks (ie. retaining wall) obscure what
is beyond
The Best of Each Capture Technique
Aerial LiDAR (Nadir; Vertical down)
Provides low density macro-level data extending
coverage
Areas like behind buildings, private property etc
will be collected
Building roof tops etc can be captured as it is
“vertical down”
Coverage of data at underpass not available
Coverage of data under canopy potentially
limited
Low cloud severely impacts LiDAR collection
Benefits of LiDAR Fusion
When used in tandem, the resulting dataset(s) provides a comprehensive insight that is greater than the sum of the parts.
Cross sections from ROW limit to ROW limit
Mobile LiDAR
Void
Aerial LiDAR Supplement
Benefits of LiDAR Fusion
Integrated data set with
complete and extended coverage
Complete data coverage including the areas of
underpass, bridges, under canopy etc.
Dr.Srini Dharmapuri LiDAR Scientist
Michael Baker Jr., Inc.
Beaver, PA
sdharmapuri@mbakercorp.com
724-495-4154
Merging of Aerial and Mobile data
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