Potential of UAVs for Beach Profiles of Low

Lying Islands

Pacific Islands GIS&RS User Conference 2012, Suva

Wolf Forstreuter

Classic Beach ProfilesClassic Beach Profiles

Image to Image Correction of Historical Photos

Image to Image Correction of Historical Photos

19681968 20002000

GIS Overlay

• Visualisation of change

• Quantitave area analysis

First DTM GPS Survey

RTK GPS at Suva Sandbank

The Survey Data

SimulationDTM-1 minus DTM-2

Secondary Base Station at the Beach

Line of sight to rover unit

5 hours recording parallel to base station at high school

Line of sight to rover unit

5 hours recording parallel to base station at high school

Position Recording

Locating the position Adjusting the pole

Locating the next positionRecording

Extre

mely

time co

nsum

ing,

every

point ~ 5 m

inutes

UAVs Alternative ?

• Can be transported easily to and reassembled on the Pacific Island

• Only needs one SOPAC operator• Operator based at SOPAC could

service one island after the other

The Requirements

• 20 – 30 cm contour lines– About 5 – 7 cm vertical accuracy

• Volume calculation and volume change detection after 5 years– Absolute orientation to WGS84

• DTM calculation on the island

Helicopter Type

Not optimal for stereo images

Different Fixed Wing UAVs

Talks with Different UAV Companies (fixed wing)

• Trimble Navigation• AVI System• MAVINICI• FOTOMAPY• GeoScan• AGISOFT• Drone METREX

The Virtual 3D Environment

• Calibrated cameras

• Relative -• Inner -• Absolute

orientation• Manual

analysisSoftware

has deve

loped

New Software

• Calibrates the camera from the points detected in images

• Handles the relative and inner orientation

• Needs ground reference points called image reference points

• Creates absolute oriented DTM

Image Reference Points• Stones as image reference points ?• NO

Image Reference Points

• Flat disks• Black cross• ~ 16 distributed over the block

covering all height levels• Survey grade GPS survey!

Overlap of Images

• 80 % in flight direction

• 60 % between flight strips

• 4 parallel flight strips necessary

Every RIP must be visible on 15 images

Flight Planning

• Blocks of ~ 2 km • UAV has to fly

straight lines with clear overlap

UAV Height over Ground

• Time between exposures and pixel size determines flight height

• 80 % overlap is a must

100 – 120 m

Est. Time Requirements

• Installation of main base station• Installation of secondary base

station• Establishment of RIP 1.5 h/block• Preparation of UAV incl. flight

planning 0.5• Flying UAV 0.5• DTM establishmentThree block

s / day

Three blocks /

day

Position UAV Handling

Requirements:• Handling & maintenance of UAV• Handling and updating flight

planning software• Handling survey grade GPS• Handling DTM software (photo-

grammetric knowledge)

Political Requirements:

A. Countries have to allow operating UAVs on outer islands

B. Countries have to address demand

Thanks