6/17/2018

Agenda (12:30 - 4:30pm, 240 min)

  • Introductions and Setup (~15 min)
  • Mini-lecture: What Can Drones Do? (~30 min)
  • Interactive: Study Design (~30 min)
  • Interactive: Data Collection / Flight Demo (~30 min)
  • Mini-lecture: Photogrammetry Concepts (~10 min)
  • Interactive: Data Processing Lab Part 1 (~20 min)
  • Mini-lecture: Ground-control Points (~5 min)
  • Interactive: Data Processing Lab Part 2 (~20 min)
  • Mini-lecture: Regulations and Safety (~10 min)
  • Interactive: Data Processing Lab Part 3 (~10 min)
  • Mini-lecture: Data Management and Computing (~10 min)

Introductions

  • About me
  • About you guys

Workshop Goals

Software and Workshop Materials

Part 1: What can drones do now?

Why drones, why now?

  • Scaling from plots to landscapes
  • Bridging the gap between field measurements and sattelite remote-sensing
  • Seeing the invisible: Beyond visible wavelengths
  • Counting the uncountable: Computer vision
  • The technology is getting (relatively) cheap and robust

What can drones measure?

High-res Orthophotos

Plant Health / Cover

Terrain / Flow Models

Vegetation Height / Structure

Hyperspectral Measurements

Object Detection

What types of platforms are out there?

  • Multicopters: Stable, Slow, Manuverable, VTOL

  • Fixed wing: Fast, Long-ranging

Pay a lot or a little

Multicopters:

  • Pro-sumer (<$2000, payload < 200g, 20 - 30 min flight time). e.g. DJI Phantom 4
  • Professional (>$4000, payload < 3kg, 30 - 45 min flight time): e.g. DJI M600

Fixed-wing

  • Pro-sumer (<$2000, payload < 100g, 30 min flight time): e.g. MapIR Magpy
  • Professional (>$6000, payload < 1kg, 60 min flight time): e.g. Aeromapper Talon, Firefly6 Pro

Passive Sensors

  • Stabilized RGB Cameras: DJI Zenmuse (Built-in)
  • Modified RGB/NIR Cameras: MapIR Survey 3 (80g, ~$500)
  • True Multispectral Cameras: Parrot Sequoia+ (~100g, ~$3000)
  • Thermal Imaging: FLIR Duo Pro R (~100g, ~$4000)
  • Hyperspectral Imaging: Headwall Nano-hyperspec (~300g, ~$22000)

Active Sensors

  • LiDAR - Phoenix miniRANGER (2.5kg, ~$10,000)
  • L-Band Radar (Soil Moisture): Black Swift Technologies (?,?)

Part 2: Study Design

How do you design a drone study?

Sampling the Landscape: Three general designs

How large an area can you survey?

Survey Area - f(Ground Resolution, Sensor, Flight Time)

Quadcopter DJI Phantom 4 Pro (20 Mpix RGB Camera):

  • 2 mm ground resolution, 10m height: ~1 ha per flight
  • 3cm ground resolution, 120m height: ~40 ha per flight

Fixed-wing Firefly6 Pro (40 Mpix RGB Camera):

  • 3cm ground resolution, 120m height ~200 ha per flight

Other constraints

  • Maintain Visual Line-of-sight: DJI Phantom - ~500m
  • Max altitude: 400 feet (~120m) AGL

Design your own study.

Brainstorm a study design (10 min)

Then share and refine it with a team of two (10 min)

Helpful Queries:

  • What are the scientific questions?

  • What measurements are necessary?

  • What UAV-based sensors might you use?

  • What ground resolution do you need?

  • Survey design: Wall-to-wall? Plots? Transects?

  • Platform Type: Quadcopter? Fixed-wing?

  • What would be the overall hardware cost?

Part 3: Preparing to Fly

OK, Let’s (prepare to) Fly!

Goal: Build a 3D model of the Townsite.

Requirements:

  • ~3cm ground resolution

  • 66% overlap between images

Flight Planning Demo:

  • R Script Demo

  • Litchi Mission Hub Demo

Let’s Fly!

Meet behind the Natural History Building in 5 minutes.

Part 4: From Images to Maps and Models

Basic photogrammetry concepts

Photogrammetry - Making (correct) Measurements from Photographs

Orthorectification

Undistorting photos to get a true “top-down view”

Orthorectified Photo = Orthophoto

Structure from Motion (SfM)

Why Proprietary Software?

  • Patented algorithms for components of SfM
  • Good interfaces for 3D modeling are hard to build.
  • Agisoft Photoscan - Fast, Stable, Easy to Use, Relatively Cheap

On your own

Follow the preparation steps (up to Stage 1) in the tutorial from NCSU

Add photos from the data folder using Workflow -> Add Photos…

Agisoft Photoscan Interface Tour

On your own

While we are waiting: Ground-control Points

  • Located in the field with a high-accuracy GPS.
  • Improves geometric accuracy of resulting maps.
  • At least 3, ideally 7 - 10 per flight

On your own

Follow the steps in Stage 2 of the tutorial from NCSU in order to locate the GCPs in photos.

Then follow the steps in stage three through the step Menu > Workflow > Build Dense Cloud. This will take a while to process.

While we are waiting: UAV Regulatory Environments

Federal Aviation Administration (FAA) considers drones to be aircraft

Key Regulations

  • Airspace restrictions - near Airports & Military Bases

  • Temporary flight restrictions - Air Force One, Fire Fighting, etc.

  • Line-of-sight, visibility, and wind requirements.

Land Management Agency Requirements:

  • NPS - No drones at all except in a few parks

  • USFS, BLM - Must get a special use permit

  • Designated Wilderness - No drones

  • State Parks - Varies by state and park.

RMBL Requirements:

  • 10m from roads, trails and people

  • Comply with FAA regulations

  • Minimize conflict with other researchers

  • Coordinate with science director Jennie Riethel

On your own

Follow the steps in Stage 3 of the tutorial from NCSU in order to build the 3D Mesh and Texture.

Safety & Consideration

  • Programmed Flights - avoid trees by >4m, pay attention to overhead wires

  • Low-elevation flights (<20m) - ground-following flights using a high-res DEM

  • Private property - DroneHunter, Assumption of Surveillance

  • Be conspicuous and friendly, take time to explain the purpose of the flights

Computing Hardware and Storage

  • GPU vs CPU Performance

  • 300 minutes of flight time / week = 120GB / Week of Imagery

  • Processing in the cloud - Paperspace virtual servers.

Burning questions

Did we cover everything?

Extending your knowledge.

Image Credits