2010 LiDAR Collection in West Virginia’s Coal Fields

West Virginia GIS ConferenceJune 9, 2010

AOC and future mining LiDAR

Slide 2

LiDAR collection specifications

• Horizontal postings: 1 meter

• Vertical accuracy: 15 centimeters

• Additional derived data products include:– ESRI elevation grid– Hillshade– 2 foot contours used in AML program– Intensity image useful in QCing LiDAR data

• ~ 2 TB of data before derived products

Slide 3

Slide 4

LiDAR Technology

LiDAR = Light Detection And Ranging•Capable of emitting 100,000 pulses per second at altitudes less than 1,100 meters•Day or night operation•Capable of collecting millions of elevation points per hour•All digital: no intermediate steps to generate digital XYZ•Rapid turnaround: Capable of processing within a week•Multiple returns per pulse •Airborne: Easy to mobilize and demobilize•Non-Intrusive: capable of accessing remote areas

Solid state Class IV laser

Swath width: Variable; 0 to 0.93 x altitude (m)

Horizontal Accuracy: 1/2000 x altitude

Elevation Accuracy: +/- 15 cm (or better)

Typical spot center spacing is from 0.5 m to 5.0 m

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•Acquisition

NOAA

Processing

Product

Workflow

Slide 6

•Pulse rate frequency (PRF)•Scan frequency•Scan angle•Desired overlap•Altitude•Make sure above parameters yield an acceptable resolution

Flight Planning

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• Pre-Flight– Check aviation weather– Review day’s mission with pilots and ground crew

• In Airplane– Check system– Power up– Communicate with ground control operator– Initialize GPS/IMU

• In Flight– Transit to project area– Begin collection– Constantly monitor conditions during collection– Keep flight log

• Post Flight– Final initialization on GPS/IMU– Power down– Retrieve removable hard drives for data decoding and processing

Acquisition Process

Slide 8

Two Topcon Hiper dual frequency static GPS receivers equipped w/ FC-100 controllers.

20 channel integrated GPS receiver

Signals Tracked – L1/L2 C/A Code and P

Code (dual frequency)

76 mb of Memory

Advanced Multipath Reduction

Logging Intervals of up to 20 times per second (20Hz)

Horizontal – 3mm + 0.5ppm

Vertical – 5mm + 0.5ppm

Cold Start - < 60 sec

Warm Start - < 10 sec

Reacquisition - < 1 sec

Ground Control

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Ground GPS Requirements

• Base station must be within 30 km (18 miles) from airborne laser.

• Use dual frequency GPS receivers.• Use two highly accurate published geodetic control points

during airborne data collection to provide redundancy.• PDOP of 4 or less, optimal 3 or less.• Data collected from at least 6 satellites at 1 second

epochs.• Base stations must have a clear view of the sky with

limited mulitpath.

Ground Control

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GPS Planning

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SBET

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ALTMStorage

DownloadHard Drive

QC Data

PosPac

Extract / Decode Laser Data File

Process GPS

ComputeLaser Points

Output Laser Points

Microstation

Raw Laser Data

IMUInformation

Processing Workflow

Slide 13

Calibration

Building an ICI (=isolated computing island)• Isolates one or more VERY high

performance computers from central IT C&C during VERY long compute jobs:– No pushes of server OS upgrades– … followed by the requisite reboots– Isolate from dependence for TIPS licenses

via pool of WVDEP licenses network outages

– Enough local storage to create a peer-to-peer within-the-room network

– UPS on each PC

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PC specs• HP800 workstations with 64 bit OSes

super modular.

• Single quad core CPUs 5th fastest on the planet when we purchased the boxes

• 16 GB RAM & 6 TB each local storage

• 4 megapixel displays + CUDA card

• Isolated peer-2-peer network when working off the net

• Gigabit network connections for on Net

• Local licenses of all core apps Slide 15

Qcing LiDAR and LiDAR software

Slide 16

• QCing LiDAR deliverables– 2003 Statewide GCPs file– Multiple LiDAR datasets that overlap

difference grid calculation– Trimble R8 GNSS receivers for spot

checks– Outsource via FEMA monies

• Software 64 bit, use multicores– Virtual Geomatics– Applied Imagery’s Quick Terrain Modeler

WV CORS

The end

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