Geiger Mode LiDAR the Next Paradigm for Floodplain Management ASFPM 2015 Mark E. Romano Geospatial Product Manager
harris.com
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Geiger-mode (GmAPD) LiDAR sensor
Geiger-mode GmAPD LiDAR Sensor
Built specifically for wide-area, high-density collection
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FAQ’s Is Geiger Mode LiDAR a new technology? No - it been utilized successfully in the defense industry for over 15 years. It is only new to the commercial industry.
Why hasn’t it been available before now? Key components could not be sourced for commercial application until recently
Are Geiger Mode LiDAR data noisy? Yes “But” - in its raw (unprocessed) state it is noisier than linear systems however, this just means a different approach to processing is utilized to produce elevation data and derivative products.
Does Geiger Mode LiDAR work in daylight conditions? Yes – Commercial Geiger mode technology is designed to work in daylight (solar) conditions with a minimal decrease in performance.
Years of proven performance in real world operations and applications |
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High Power Low Sensitivity
Approximately 500KHz sample Rate for single scanner designs
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Low Power High Sensitivity
200MHz vs. 500KHz |
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Collection Simulation Comparison (8ppm)
Higher – Faster – Greater Resolution |
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Collection Metrics @ 8PPM
17X
Efficiency gains keep costs down at higher collection densities |
Geiger-mode sensors sample the same spot on the ground thousands of times
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How Does it Work? • Avalanche Photo Diode Array (4096 detectors) • Photon counting device (Low light sensitivity enables use of low power laser ) • Capable of sub-ns operation (enables higher vertical measurement precision and vertical resolution) • Supports high laser Pulse Repetition Frequencies (PRF)
GmAPD Camera Uses 32x128 Flash Array
Think of it as a 3D camera |
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GmAPD Multi-Look/Multi-Pulse Collection Multi-look approach • 4096 measurements per laser flash • 50,000 flashes per second • Approx= 205 million elevation measurement per second • Every spot illuminated 1000’s of times • The dozens of photon detections are processed to determine the real objects • Programmable Forward/Sidelap
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Linear Technology Limitations
• Inefficient and costly at high resolutions • Has inherent data occlusions • Foliage penetration is limited by single sample approach • Limited-range resolution (target separation)
Limitations with single sample/look systems
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Single Look Linear Artifact Example1
Shadows (occlusions) from linear scanners
Occlusions due to single look angle
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Single Look Linear Artifact Example 2
Vegetation Shadows (occlusions) from linear scanners
Limited FOPEN due to single look angle |
NON-Export Controlled Information |
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Single Look Linear Artifact Example 3 Compression/Expansion effect from linear scanners
Lack of homogeneity due to varying groundspeed
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Solution multi-Look and Oversampling
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Multi-Look and Oversampling Linear
Geiger Mode
Reduces Artifacts and occlusions Provides Highly Homogenous High-Density Accurate Data |
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Reflectance Image Linear
Geiger Mode
Increases Detail Provides Highly Homogenous High-Density Accurate Data |
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High Resolution& Accuracy Result
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High Resolution& Accuracy Result
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What can I use this data for? Pre-access where risk may be present
Automated risk analysis such as HAG,s, LAG’s, and others |
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River Overbank 10ft Rise
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Barrier Island 10ft Rise
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River Bank 10ft rise
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Improving Accuracy Results Aggregating multi-look data requires highly accuracy alignment Required Inputs: • Utilize latest INS/GPS • Utilize horizontal and vertical GPS ground control objects • Opposing 50% overlap sorties create four looks (fore/aft fore/aft) Process: • Perform H/V bundle adjustment via GPS tie points • Perform auto tie point registration from multiple look angles
