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2017 LGA Pipeline Safety Conference – New Orleans, LA Scanning vs. Conventional Surveying for Large Rehabilitation and Replacement Projects July 11, 2017 Wilfred Barry and Charles Wood
2017 LGA Pipeline Safety Conference – New Orleans, LA
Scanning vs. Conventional Surveying for Large Rehabilitation and
Replacement Projects
July 11, 2017Wilfred Barry and Charles Wood
2017 LGA Pipeline Safety Conference – New Orleans, LA
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Surveying & Mapping
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LiDAR….Light Detection And Ranging• The position of the mobile vehicle
is known (from differential GPS andthe IMU [Inertial MeasurementUnit]).
• Measures distance to surfaces bytiming the outgoing laser pulse andthe corresponding return.
• Distance = time x (speed of light)/2• By keeping track of the angle at
which the laser was fired: you cancalculate the X, Y, Z position ofeach “return”.
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Uses of Mobile LiDAR in the Utility Industry• Utility Corridor Mapping • Utility Assets Mapping• Tool for aiding design for “complicated or busy” site• 2-D or 3-D modeling• Construction monitoring• As-built documentation• The dreaded forensic documentation or analysis??
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Benefits of Mobile LiDARQuick turnaroundImproved safety by decreasing the time crews spend in
construction sitesDecreases the disruption to the contractorComprehensive, no need for costly return tripsGreat archival tool for later modificationsAccurate locational data to 1/10 of a foot, or better with
use of controlData is generated in 3-D, so there is no need for
conversions from 2-D.Cost effective and practical
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LiDAR Scanner Components• Lasers mounted in the scanner.• Scanning assembly – precisely
controlled rotating mirror –directing the “firing” of 32 lasers.
• Receiver for recording reflected energy called “returns”.
• Vehicle location system incorporating Differential GPS and Inertial Navigation System (INS & IMU). Velodyne HD32 spinning
at 20 Hz, capturing up to 700,000 points per second
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• Surveying while driving• Off road surveys with more
suitable vehicles• Surveying crews working
conventionally on busy highways is a significant danger to the crews and the vehicles on the road.
• LadyBug Camera has full 360⁰ imaging with 6 sensors
Mobile LiDAR Scanning with a Vehicle
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KML Photo Index
Bootlegger RoadSt. Tammany Parish
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LiDAR and Imagery
Photo 550
LiDAR Scan
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Mobile LiDAR Scanning with a Drone• Terrain is irrelevant…good weather is
more important.• FAA restrictions and licensing required.• Flight altitude limited to 400 feet
(plenty for scanner).• Range is limited to battery life and line
of sight distances.• Can see over roof tops and trees.• Dense foliage and grasses limit
penetration of lasers.
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Drone Components
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High Resolution Photography
• 4K video at up to 30fps• Record at 4096×2160
(24fps) or 3840×2160 (30/25fps)
• 16MP photographs• 12.8 stops of dynamic
range
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Flight Control
www.DroneDeploy.com
Drone Deploy
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Orthomosaic Production†
† Orthomosaic generation is the automated process for Orthorectifying the raw imagery and mosaicing (stitching) them into one single image. This process will generate a Georeferenced Image and optionally a Digital surface model in various different formats.
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Selecting Photographs
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Selecting Photographs
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Creating the Orthomosaic
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Orthomosaic UsesAssumption: The pictures are taken using a camera that writes geographic metadata into the picture and is subsequently adjusted using visible control with GPS horizontal and vertical observations:• Measuring distance within the Orthomosaic is as
accurate as picking the correct pixels...0.1% or better.• The file extension is a TIF and can be used as a “texture” for
colorizing LiDAR data that has no RGB values. Because the TIF has geo-encoded elevation data, it colorizes the correct LiDAR points. This is why it’s important that the LiDAR data and the Orthomosaic are using the same surveying control.
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Accuracies
Paved Surfaces Grassy Surfaces
No Control 0.1 to 0.2’ 0.2 to 0.4’
With Control 0.05 to 0.10’ 0.1 to 0.2’
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Mapping and Utility Locates
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Utility Locates
2017 LGA Pipeline Safety Conference – New Orleans, LA
Typical large replacement projects:Management Drivers1. Problematic gas system conditions such as unacceptable leak
histories, excessive corrosion, difficulties of system repair,persistent pressure problems from piecemeal additions, etc.
2. Obsolete piping materials and/or noncompliant piping systems3. Highway and utility improvements requiring relocation4. Growth of demand beyond current capacity
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Typical locating and mapping requirements ahead of construction1. Record maps…..are they accurate??2. Main and valve locations and depths3. Meter and service line locations and depths4. Other utility locations – particularly wastewater
service lines – for conflict avoidance.5. Desired accuracies for locating conflicts
a. Horizontal: 2 – 3’ minimum†, 1’ preferredb. Vertical: expectation is normal depth for the utility,
depth data dictated by need and importance†LA One Call allows a tolerance of 18”, each side of the facility width. This can lead to a large width for the possible location.
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Conventional procedures used in locating utilities
1. Initiate LA One Call locate requests and track results.2. Prepare base maps from clipping recent imagery, usually from
Google Earth or Bing.3. Request record maps from utilities that do not mark.4. Utility locate crews walk and pick up details of One Call marks,
laying conditions and potential conflicts. Utility locate crewsperform additional locating of underground utilities, markingand placing pin flags where needed.
5. Survey crews GPS RTK (real time) marks and “connect the dots”.6. Survey technicians draft from images and survey notes.7. Base map is complete and ready for design.
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Scanning procedures used in locating utilities
1. Initiate LA One Call locate requests and track results.2. Request record maps from utilities that do not mark.3. Prepare base maps from clipping recent imagery, usually from
Google Earth or Bing4. Utility locate crews walk and pick up details of laying conditions
and potential conflicts. Utility locate crews perform additional locating of underground utilities, marking and placing pin flags where needed.
5. Truck or drone scan project streets and alignments.
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6. Survey crews GPS RTK (real time) marks and “connect thedots”.
7. Survey technicians draft from images and survey notes.8. Base map is complete and ready for design.
Scanning procedures used in locating utilities cont’d
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Scanning and SUE tools and procedures used in locating utilities1. Initiate LA One Call locate requests and track results.2. Request record maps from utilities that do not mark.3. Prepare base maps from clipping recent imagery, usually from
Google Earth or Bing4. Utility locate crews walk and pick up details of laying conditions and
potential conflicts. Utility locate crews performs additional locating of underground utilities, marking and placing pin flags where needed.
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5. Utility locate crews performs additional locating ofunderground utilities, marking and recording locations using asmart tablet with GPS and imagery on board providingsegregated layers by utility and owner.
6. Truck or drone scan project streets and alignments for basemap purposes recording all visible topo to cm accuracies.
7. Survey crews GPS RTK (real time) marks and “connect the dots”8. Survey technicians draft from images and survey notes
imported files and alignments from the smart tablet. 9. Base map is complete and ready for design.
Scanning and SUE tools and procedures used in locating utilities cont’d
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Field Tools for Location Mapping
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Field Tools for Location Mapping
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Additional advantages of preserving location and imagery (unquantifiable)1. Preserves knowledge of existing conditions (may avoid
future controversies and claims).2. Provides evidence of what conditions were like before
construction started (pavement cracks, landscaping,etc.).
3. Genesis of record maps.
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Disadvantages of preserving location and imagery data1. Data intensive: files easily get into the gigabyte size
range.2. Will change back up procedures and equipment.3. Archival and retrieval of the data can be problematic
with file sizes, various software types, and to provideaccess to those that need it.
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Costs and Production Rates• Scanning and drone vehicle $1,500 to $2,500 per day
depending on crew requirements and mobilization• Scan processing $1,000 per day for LiDAR and PIX4D• Processing time is about two days to each day of scanning• Drone scans are flown for the same area twice at 90⁰ apart and
scan up 150 to 200 acres per day (50 acre limit imposed by battery life). Linear projects about 6 to 10 miles per day flown out and back.
• Vehicle scans can produce about 40 miles a day, or 20 miles of linear projects that are scanned once in each direction.
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Software Credits…• Inertial Explorer processing of the INS trajectory by Novatel• Point Cloud Export and colorization by LiDARUSA• LadyBug image processing by Point Grey Research, now
owned by FLIR Systems, Inc.• LadyBug Export of panorama and 2-D jpegs by LiDARUSA• Pix4D orthomosaic by Pix4D, Inc.• Global Mapper ground classification (DEM) by Blue Marble
Geographics• Quick Terrain Modeler point cloud colorization and
management by Applied Imagery• TopoDOT feature extraction for TIN and cross section development
by Certainty 3-D
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Questions?
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Thank you!!
Scanning vs. Conventional Surveying for Large Rehabilitation and Replacement ProjectsSurveying & Mapping �LiDAR….Light Detection And RangingUses of Mobile LiDAR in the Utility IndustryBenefits of Mobile LiDARLiDAR Scanner ComponentsMobile LiDAR Scanning with a VehicleKML Photo IndexLiDAR and ImagerySlide Number 10Drone ComponentsHigh Resolution PhotographyFlight ControlOrthomosaic Production†Selecting PhotographsSelecting PhotographsCreating the OrthomosaicOrthomosaic UsesAccuraciesMapping and Utility Locates Utility LocatesTypical large replacement projects:Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Field Tools for Location MappingField Tools for Location MappingSlide Number 31Slide Number 32Costs and Production RatesSoftware Credits…Questions?Thank you!!
