FEMA Dam Safety Technical Conference
Integrated Acoustic and Laser Mapping
Burr Bridge
Outline
• Objectives
– Structural and safety inspections and surveys
– Support permitting, design, and construction
• Overview of Mapping Technologies
– Focused on high resolution multibeam echosounder (MBE)
and LiDAR data
– On/below/above water applications and methods
• Project Data examples:
– Dam and pipeline river crossings
– Integrated point clouds, digital terrain models (DTM),
charts, solid models and simulations/annimations
Hydrographic and Laser Survey Objectives
• Structural and safety surveys and
inspections
– Survey, inspect and model above and
underwater structures and intakes
– Locate and map debris fields/hazards
– Identify areas of concern (e.g. scour,
slumps, voids)
• Support permitting, design, and
construction
– Map site bathymetry and geology
– Reservoir volume capacity/surface
area
– Sediment transportation and scour
3
Marine Survey Technologies
• Sonar Systems
– Single beam echo sounders
(SBES)
– Vessel and Tripod mounted
Multibeam Echosounders
– Sidescan/Interferometric sonar
– Synthetic aperture sonar
– Seismic/sub-bottom profilers
– Imaging and scanning sonar
• Other On-water and/or Terrestrial
Surveys and Methods
– 3D laser scanning and
photogrammetry
– Current meter/Doppler velocity
studies
– Dye Studies
– Magnetometer/Electromagnetic
4
Why Use Remote Sensing?
Technical and Logistical
Complexities
• Complex structures and
bathymetry
– Vertical faces,
overhang/undercuts, voids,
tunnels
• Improved Safety
– High water flow
– Turbid and low visibility
conditions
• High operating efficiencies
– Wide area coverage/survey
• Data can be “mined” and applied
to numerous project applications
from the office
Integrated Multibeam Sonar and LiDAR Data
Applications
• Map, inspect and model of underwater sites and structures
– Document existing conditions for repair, retrofit and construction
efforts
• Geo-referenced data above/below water
• Combined datasets fill data gaps not mapped with one method
• Well suited for use at “complex” sites
Acquisition – Vessel Mounted Multibeam
Sonar and LiDAR
• Single and dual head sonar
• Side and bow MBE mounts
– Typically rotated 30 deg for
structural
mapping/inspection
• LiDAR mounted on vessel,
vehicle or tripod
• Ancillary equipment
– Inertial navigation sensor
(INS)
– Real-time kinematic GPS
– Sound velocity sensors and
profilers
• Acquisition software
Acquisition – Vessel Mounted Multibeam and
LiDAR
Data Products – Volume Capacity, Surface
Area vs. Water Elevation
Acquisition – Scanning Multibeam Sonar
Image Curtesy of Teledyne BlueView
• Hand or davit deployed on
tripod or moving platform
• Scans 360 degree sphere to
maximum range of ~30-90 ft
– Stationary and upright
when not mobile
• 2D and 3D systems
• Real-time display during
collection
• Each scan collected
separately, aligned with
adjacent scans
• Baseline bathymetric data
(MBE or SBE) aids in
alignment and georeferencing
Acquisition –Scanning Multibeam Sonar
Image Curtesy of Teledyne BlueView
Example Data – Point
Cloud and Solid Model
Example Data Products – Monitoring Change
Pre (green) / Post (yellow)
Pre-dredge
Post-dredge
Example Data Product – Draft Tubes/Tunnels
cinder block
Example Data – Draft Tubes/Tunnels
Example Data – Bathymetry DTM, Scour and
Structural Mapping
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Bathymetry DTM, Scour and
Structural Mapping
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Dam1 Point Cloud
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Dam1 Cross Sections
Vessel mounted
multibeam data
Vessel mounted
multibeam data
combined with
bottom deployed
scanning MBE
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Dam Deposition and Scour
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data– Dam
Charts
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Pipeline Point Cloud
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data - 2D Bathymetric and Pipeline Profiles
Example Data – Monitoring Pipeline Armor Placement
“TIMELY, TAILORED, AFFORDABLE MAPPING SOLUTIONS IN ALL PHASES OF UNDERWATER PROJECTS”
Example Data – Dam2 Point Cloud
Summary
• Efficient acquisition in complex areas with limited visibility were
diver safety is a concern
• Data are georeferenced allowing it to be merged
– Combined datasets fill data gaps not mapped with one sensor
alone
– Combine with other types of georeferenced data
• Numerous data products and other survey technologies available
to meet project needs
– Monitor and measure change (repeatable and georeferenced)
– Supports engineering, environmental, archeological studies
– Aids permitting, repair, retrofit and construction design efforts
– Once collected data can be “mined” for various project needs,
minimizing need to revisit site
What’s being Improved and Innovative?
• Increased use of 3D underwater laser scanning
• Remote and autonomous acquisition
– Surface and underwater vehicles
• Merger of technologies and software across professions
and industries
• Higher resolution data
– Full ping rate dual head sonar
– Multi-detect anticipated to further increase resolution of data
products
• Comparison with base models
Questions?
30
Burton Bridge, ASCM Certified
Hydrographer
Tetra Tech, Marine Mapping Group
Office: 425.482.7859
Cell: 425.299.2835
[email protected]
www.tetratech.com