67th MSPS Annual Meeting - 2019

Unmanned Aircraft Systems (UAS) As a

Tool for Land Surveyors

George Southard

GSKS Associates LLC

George Southard:

Master’s Degree in Photogrammetry and Cartography

40 years working in the mapping industry

Owner – GSKS Associates LLC

“Consulting for the Geomatics Profession”

Introduction

Why Use a small UAS for

Photogrametric Mapping?

• Create accurate geometric map products; like,

topographic maps, planimetric maps, orthophoto

maps, etc. of relatively small areas of interest.

Small UAS can be used to:

• often cheaper, and faster than by terrestrial

methods,

• in areas inaccessible by ground crews,

• with very high accuracy and precision.

and they can do it :

Why small UAS/Photogrammetry?

This technology is ideal for measuring areas or

objects such as:

– Areas to be mapped are 20-600 acres

– Corridors – Electric utilities, pipelines, etc.

– Objects/areas that are too

• Hot or cold

• Soft

• Delicate

• Danergerous

• Inaccessible

• Toxic or Radioactive

Why small UAS/Photogrammetry?

Large (Predator Drone)

Medium UAS (weighs 90 lbs.)

sUAS (Small Unmanned Air System)

1lbs < 55lbsMicro (MAV) less than 1lbs

A Variety of Types and Sizes

Rotary

BlimpFixed-Wing

A Variety of Types and Sizes

Traditional Surveys vs. UAS Surveys

• Slow, high labor costs

• Work in harm’s way

• Reduced accuracy due to

low sampling density

• Low accuracy due to

inability to ‘see’ the tops,

valleys in stockpiles

Traditional Land Surveys

• Slow, high labor costs

• Work in harm’s way

• Reduced accuracy due to

inability to ‘see’ the entire

stockpile

“Holes”

Terrestrial Laser Scanning

• Major access issues

• Work in harm’s way

• Inaccurate due to

inability to ‘see’ the

entire stockpile

• Relatively expensive

“Hole”

Access - Can’t get around

many piles

Lack of access

“void”

Mobile Laser Scanning

• Can be very accurate, dense data

• Out of harm’s way

• Expensive

• Not very responsive (long lead

times, weather delays, clouds, etc)

• Huge technology/price barriers to

entry for owner/operators

Manned Aerial Survey-Photogrammetry

• Very Accurate, dense data

• Out of harm’s way

• Relatively inexpensive

• Very convenient (short

mobilization times)

• Relatively small

technology/price barriers to

entry for owner/operators

• Restricted to small areas

Unmanned Airborne Survey

small UAS technology

sUAS → mass < 55 lbs

Micro-GPS

Receivers

Light weight high

capacity Batteries

Small Hi-

Res

Cameras

MEMS

IMUs/gyros

Enabling technologies

Typical Camera Choices

Video

Inspection

Quality B

3D Mapping

Quality C

Orthos

Quality A

3D Mapping

Imaging Payloads

Canon S100

12 MP

Horizontal RMSE =

6.4 cm

Vertical RMSE =

14.0 cm

Sony NEX-5

16 MP

Horizontal RMSE =

1.3 cm

Vertical RMSE =

1.9 cm

Does camera choice effect accuracy?

Camera Sensor Dimensions

(mm)

Rows x Columns (pixels) Pixel Area (μm2)

Canon S100 7.5 x 5.5 4000 x 3000 (12MP) 3.4

NEX-5R 23.4 x 15.6 4912 x 3264 (16MP) 28.8

The light collected is proportional to the sensor pixel area. Note

that the NEX has 8 ½ times the area of the Canon – this is a huge

difference!

Photon noise varies as the square root of the image signal, so

collecting more light results in proportionally less noise, i.e. a

higher signal-to-noise ratio is achieved.

Higher signal-to-noise means more sensitivity to low-light

situations, and broader dynamic range.

Sensor Size vs. image noise

Significant

Noise

Poor Conformance

Noise from Cannon S100 images

Image Noise

Noise from NEX-5R Images

Low

Noise

High Conformance

Image Noise

Focal length is highly

correlated with vertical scale

and accuracy

Precise focal length cannot be

established for zoom lenses,

even if the zoom feature is

disabled.

Focal length calibration

• Consumer cameras do not have a Mid-Exposure Pulse

(MEP)o Real Time Kinematic GNSS

o One must know the exact correlation of each photo center to the GNSS position at

time of exposure

o Common practice is to use the camera flash signal to create a MEP with

modifications to the electronic circuitry

• Consumer cameras do not offer stock fixed focus lens

optionso Requires special lenses (which are expensive or not available for many consumer

cameras.)

Other Issues….

LIDAR

Now available for sUAS

Chock full of noise …

Low end systems need work!

LIDAR Data Set

Significant vegetation penetration

LIDAR Required for Vegetation Penetration

WorkFlow

Fly, QC,

re-fly

Georeferencing Stereo

Images

Analyze, Map

Plan

small Unmanned Aircraft Systems

Mission

Planning

Ground Control

Planning

Establish

Control/Check/

Base Station

Workflow

Fly Field Check

Georeference

Photos

Create a

“block”

Add GCPs/

Process RTKQC

Generate Point

Cloud,

Orthomosaic

Load into

exploitation

software

Test Horizontal

& Vertical

Accuracy

Product

Creation

Generate

DEM

Generate

Contours

Volumetric

Analysis

Cross

Sections

Other

Products

Workflow (cont)

Ground control for accuracy

Controlling, Checking

Good control to the airborne GPS data…

Local,

permanent

base

Temporary

base station

Virtual

Reference

System

NGS, other

CORS

RTK/PPK Reference Options

Corona Calibration Target –

W Arica Rd & Peart Rd, Casa

Grande, AZ

Semi-permanent target,

sand mine near Memphis,

TN

Verification is always necessary

Defining the Project Area

Defining and planning the Flight

Upload Flight Plan to UAS

Flight Execution

Download Flight Data for Processing

Mission

Planning

Ground Control

Planning

Establish

Control/Check/

Base Station

Workflow – Imaging/Data Processing

Fly Field Check “Align” Photos

Add GCPs/

Process RTKQC

Generate Point

Cloud,

Orthomosaic

Remarkably Good Results

data processing

using the science of

Photogrammetry

Remote Photogrammetry

”The science or art of obtaining reliable

measurements by means of photographs.”

”Photogrammetry is the art, science, and

technology of obtaining reliable information

about physical objects and the environment

through the processes of recording, measuring,

and interpreting photographic images.”

(ASPRS, 1980)

Definitions:

Analog Photogrammetry

Using optical/mechanical/electrical instruments, to perform measurements from images printed on paper, film or glass, thus creating stereographic views of the image space for the purpose of 3D measurements.

Analytical Photogrammetry

Using equipment similar to those used in analog photogrammetry but which have computer/electronic components added for more efficient measurement of photographic images. Computer software programs are also a key element in these operations.

Digital or Softcopy Photogrammetry

The performance of photogrammetric operations using digital rather than hardcopy images. This work is accomplished primarily using computer, monitors, and a specially designed mouse along with sophisticated software.

Definitions:

History

Origins of Remote Sensing

First photographs taken in 1839

Remote sensing began withaerial photography

A brief history of Photogrammetry

1858 Gasper Felix Tournachon "Nadar" takes photograph of village of Petit Bicetre in France from

a balloon.

Paris by Nadar, circa 1858

A brief history of Photogrammetry

City of Boston by Black and King (1860), from hot air balloon

A brief history of Photogrammetry

A brief history of Photogrammetry

Major developments in aerial photography – WW1

A brief history of Photogrammetry

After the war the technology was in place to begin large scale aerial surveys

A brief history of Photogrammetry

Photogrammetric Fundamentals

First Assumption: the photo image is a flat planar surface

Second Assumption: There are planar distortions in all photo images:

- Distortions come from two sources

1) the camera platten for film or the CCD platten for

digital images

2) the camera lens(s)

Photogrammetric Fundamentals

Photo Orientation

Six positions of orientation are needed to georeference each photo

Ω Omega – Yaw Φ Phi – Pitch Κ Kappa - Roll

x – Longitude y – Latitude Z - Elevation

Known constants and variables…..

Precisely controlled image capture…..

Precisely controlled image capture…..

•Over lap about 60%

Aerial Photography -Stereo pair

•Over lap about 60%

Precisely controlled image capture…..

Types of Photogrametry

Photogrammetric Types from Applications Point of

View (d is distance from camera to object)

▪ Close Range Photogrammetry d<50 m

▪ Aerial Photogrammetry 50m>d<15km

▪ Space Photogrammetry d = 300 km+

Photogrammetric Types

Close Range (terrestrial) Photogrammetry

Close Range (terrestrial) Photogrammetry

Aerial Photogrammetry

Space Photogrammetry

❖ Extraterrestrial pictures taken from space-based cameras

Types of Images

• Panchromatic, Black & White, Grayscale

• Color - Red Green Blue (RGB)

• Multispectral (RGB + Infrared)

• Hyperspectral

Introduction

Types of photographs (categorized by tilt)

• Vertical - camera axis as nearly vertical as Possible

• Oblique - camera axis intentionally tilted• Low Oblique

• High Oblique

Types of photographs (categorized by tilt)

Vertical - Aerial Photo

❖Mainly used for mapping

Low oblique (no horizon)

❖Seldom used for mapping

Low Oblique – Aerial Photo

• Horizon line in the

photo

• Typically used for

3D city modeling

High Oblique – Aerial Photo

• Maps are based on parallel projection while photo has central projection

• Maps have a unique scale. Photo scale varies depending on terrain relief and degree of radial distortion

Characteristic of a Map vs a Photo

Aerial images are not maps!

Image Acquisition for photogrammetric mapping

• Photos taken in parallel flight strips

Image Acquisition

• Each successive photograph overlap previous photo

Image Acquisition

Full Ground Control vs. Aero-triangulation

Types of Stereo Model control layout

Full Stereo Model

Control

Stereo Model Control for

Aero-triangulation

Ground Control Point Planning

Types of Ground Control Points

Types of Stereo Model control layout

Full Stereo Model Control – with Aero-triangulation

Aero-Triangulation - (georeferencing all images for a unified

block of ground control positions and tie points)

Types of Stereo Model control layout

Photogrammetric Instruments

• MULTIPLEX MODEL SKETCH

Direct Optical Projection Stereo plotters

Kelsh – Optical/ Mechanical Stereoplotter

1930s to 1970s

Direct Optical Projection Stereo plotters

Wild Heerbrugg A8–Analogue Optical Mechanical Stereoplotter

1960s to 1980s

Direct Optical Projection Stereo plotters

• Wild BC2 analytical stereo-plotter.

Analytical Optical/Electronic Stereoplotter

1980s – 1990s

Direct Optical Projection Stereo plotters

Digital Softcopy Stereoplotter

1990s - Present

Softcopy (digital) Stereo plotters

Wild C2 - 1927

Wild RC5 - 1944

Wild RC30 & Zeiss TOP15 – 1980s

3D Aerial Film Cameras

• Airborne Imagery Cameras - Manned Aircraft:

• Large Format

• Medium Format

• Small Format

RGB and IR≥200 MP

RGB or IR60 - 100 MP

RGB or IR10 – 20 MP

3D Stereo Digital Imaging Cameras

• Airborne LIDAR: Manned Aircraft

Wide Area Mapping500-800 kHz pulse

rate

Corridor Mapping200-500 kHz pulse

rate

OR

3D LIDAR Scanning

• Airborne LIDAR: Unmanned Aircraft

3D LIDAR Scanning

• Airborne Imaging & LIDAR: Unmanned Aircraft

High Quality Photogrammetric Mapping – Calibrated Lens Distortion, Mid-

Exposure Pulse, Fixed Focal Length

Medium Quality – Photogrammetric Mapping, Lens characterization, no MEP

Imaging only, no photogrammetric mapping, no lens correction

3D LIDAR Scanning plus Imaging

UAS Survey GNSS Survey Comments

Area 1.5 km2 1.5 km2

Ground control setup &

measurement

1 ¼ hr --- Ground control not required

for all applications

Setup time 15 min 15 min (per day)

Survey time 45 min 30 ½ hr (4 days)

Tear-down time 15 min 15 min (per day)

Data processing time 4 hrs

(2.80 GHz Intel Core i7,

16 GB RAM)

--- Data can be processed

overnight

Total time 6 hr 30 min 32 hr 30 min 5x faster than GNSS

Measurement sampling Distance 3.8 cm (at 120 m flight

altitude)

15 m Minimum sampling size is 2.4

cm

Horizontal accuracy 2 cm 1 cm

Vertical accuracy 4 cm 2 cm

Land Survey vs. UAS Survey Example

Surface model generated from UAS

survey (± 300,000 measurements)

Surface model generated from GNSS

survey (±1,000 measurements)

Topographic Survey Comparison

Project Project

Number

ofGSD AREA #GCPs Software PROCESSING RMSE

TYPE LOCATION IMAGESper pixel Covered

VERSION TIME³ X, Y Z

Mining Canada 185 4.4 cm 0.26 km² 8 PhotoScan Pro 2 hr 4.0 cm 10.3 cm

Forestry Alaska 372 5.2 cm 0.83 km² 11 Pix4UAV 6 hr 3.4 cm 4.2 cm

Test field Belgium 400 4.6 cm 0.84 km² 8Stretchout™ 20 min 6.4 cm 12.0 cm

Pix4UAV 5 hr 1.6 cm 3.0 cm

Mining USA 640 5.5 cm 1.2 km² 5 Pix4UAV 10 hr 1.9 cm 3.7 cm

River Bank Spain 2504 8.1 cm 13.1 km² 27 Cloud 48 hr 4.5 cm 9.5 cm

Golf Course Switzerland 510 13 cm 2.5 km² 8 PhotoScan Pro 4 hr 9.2 cm 27.4 cm

Accuracy Comparisons

• Engineering & Surveying

• Mining

• Civil & Heavy Earthworks Construction

• Oil & Gas

• Environmental & Landfill

• Public Agencies

• Agriculture & Forestry

Target Markets

Some Things to consider:

• Do you really need a UAS? • Be sure you really know why you want a UAS

• Know what kind of work you expect to do and what types of deliverables

you plan to produce

• Some common applications– Construction management

– Open pit mining

– Stock pile inventory

– Landfill management

– Bridge inspection

– Environmental monitoring

– Transmission line inspection

Before purchasing your UAS

Some Things to consider:

• What is your budget for the system?

A Rough Estimate of 1st year costs:• Equipment/SW Cost: $60K – $150K

• Pilot Salary: $40K - $100K

• Regulatory Cost: $5K - $10K

• Annual Maintenance: $10K - $25K

• Total 1st year start up: $115K - $285K

Before purchasing your UAS

Some things to consider:

• Will you need to hire additional staff?

• The typical sUAS crew for mapping & survey work consists of:

• Pilot in Charge (operator)

• Observer(s)

• Land Surveyor

• Image/data processing specialist

• Do your people have the right skills?

• Aviation training (FAA Remote Pilot minimum) for pilot and

observer

• Land Surveyor with general surveying experience and standard

equipment for establishing ground control points

• Remote Pilot and/or observer needs to have professional

photographic skills

Before purchasing your UAS

• Will work for minimum wage?

• Likes to party?

• Has medical marijuana card or

is using other non-FAA

approved medications/drugs?

• Has high score in Grand Theft

Auto?

• Family relative of the owner?

• Felony or DUI conviction?

• Poor decision making skills?

• Lot’s of life drama?

Does this describe your UAS pilot?

✓ Can study for and pass FAA

Exam.

✓ Has good vision.

✓ Has good life/work skills.

✓ VERY safety conscious.

✓ Actively improves proficiency

✓ Maintains FAA currency.

✓ Clean criminal / DUI history

Professional UAS Pilot Checklist

✓ Will not override the pilot’s

fly/no-fly decisions.

✓ Will not pressure pilot because

of deadline, client importance,

weather, etc.

✓ Will support pilot in increasing

proficiency, and maintaining

currency.

✓ Will establish, follow, and

enforce company safety policy

and all FAA rules.

✓ Invests in dedicated UAS staff.

UAS Manager Checklist

Some things to consider:

• Training needed for your UAS team

• Pilot in Charge –

• FAA operator’s course and exam

• Learn basics of aviation, air space regulations,

navigational charts, aviation weather, etc.

• UAS Manufacturer’s training

• Operations and maintenance of aircraft systems

• Aircraft safety and operations manual and training

• Detailed understanding of aerial photography techniques

• Plenty of practice with the onboard camera

• Understanding of lighting conditions and camera

settings

• Learning flight characteristics of each UAS

Before your new UAS arrives

Some things to consider:

• Training needed for your UAS team (cont.)

• Flight Observer

• FAA operator’s course and exam

• Should also be trained in system maintenance

• Land Surveyor with experience in setting ground control for

aerial photography

• Image/Data processing specialist

• Knowledge and experience with each of the various

software suites for the UAS and the final products

• Knowledge and experience preparing flight plans

Before your new UAS arrives

Some more things to consider:

• Facilities for your UAS operations.

• Secure storage for UAS system

• Space for layout, set-up, and repair work

• Vehicle for transport to job sites

• Should be large enough for equipment and crew

Including:

• 2-4 people

• The UAS with its many components

• Surveying equipment

• Launcher

• Misc. tools

• Etc.

Before your new UAS arrives

• Multiple platforms may be

necessary for multiple

mission profiles (rotor wing /

fixed wing,)

• Multiple sensors / lenses may

be necessary for multiple

mission profiles (high res /

long focal length, low res

short focal length)

• The more flexible the aircraft

and sensors, the more

mission profiles available. >

ROI

Aircraft and Sensor Considerations

• We have a confluence of new enabling technology for direct 3D modeling from sUAS platforms, is this the time for you to start using this technology?

• Sweet spot will be where the cost ground survey and flying full scale manned aircraft is too high, but UAS will work.

• Will the business paradigm shift? – will owners of mines, farms, etc. want operate their own sUAS? Will they hire you?

• Where do owners of traditional Aerial Mapping companies fit?

• Will regulations ever catch up to the advances in technology? Example… UAS can fly much higher than 400ft.

Summary & Lingering Questions

Questions