15th International Scientific and Technical Conference

From Imagery to Map: Digital Photogrammetric Technologies

Camera calibration for UAS. Different approaches

Smirnov AlexeyTechnical Support Department, Racurs

October 2015, Yucatan, Mexico

Objectives

UAS certification (MIIGAiK)

Processing UAS imagery with different calibration methods

Distortion plotting

Results analyzing

Scientific training area MIIGAiK

Department of photogrammetry

2014-2015

Cameras

Point and shoot camera

Single-lens reflex camera

Industrial camera

Objects

Area 4 sq.km.

Distortion

Physical distortion

Mixed distortion

Test № 1

800 m (GSD-6 cm)600 m (GSD-4 cm)

Phase One IXU 150 (f-55 mm)

Ground control points – 109, check points – 19

UAV Orlan-10

Gasoline engine

Max. take-off weight: 21 kg

Wing span: 3.1 m

Max. range: 1000 km

Flight altitude: 100-5000 m

Max. flight time: 10 h

Specifications

CMOS sensor

Sensor size: 8280x6208 pix

Focal length: 55 mm

Phys. pixel size: 5.3 mkm

Central shutter

Phase One IXU 150

Calibration parameters

Project

 

600 m 800 m

Calibration methods

W/O calibratio

n

Lab calibration

Self-calibration

(Phys)

Lab calibration + phys self-calibration

Self-calibration

(Mix)

Lab calibration + mix self-calibration

W/O calibratio

n

Lab calibration

Self-calibration

(Phys)

Lab calibration + phys

self-calibratio

n

Self-calibration

(Mix)

Lab calibration + mix self-calibration

Focal length

mm 55.0000 55.1407 55.3613 55.1395 55.2328 55.3738 55.0000 55.1407 55.3559 55.1127 55.2335 55.3786

Principal point (PPA,

PPS)

X, mm 0.0000 -0.1098 -0.0066 -0.1109 -0.0055 -0.1104 0.0000 -0.1098 -0.0028 -0.1162 -0.0055 -0.1098

Y, mm 0.0000 1.7203 0.0736 1.7225 0.0347 1.7202 0.0000 1.7203 0.0328 1.7228 0.0341 1.7208

Distortion

K1 0.0000 -2.4953e-05-2.2511e-05-2.4568e-05-1.6065e-05-1.6071e-05 0.0000 -2.4953e-05-2.4078e-05-2.448e-

05-1.6161e-

05-1.6087e-

05

K2 0.0000 1.1253e-08 8.023e-09 9.992e-09 9.746e-09 9.867e-09 0.0000 1.1253e-08 1.0241e-081.0045e-

089.797e-09 9.969e-09

K3 0.0000 0.0000 1e-12 1e-12 1e-12 1e-12 0.0000 0.0000 1e-12 1e-12 1e-12 1e-12

Test № 2

700 m (GSD-5 cm)

Nikon D 800 (f-50 mm)

Ground control points – 96, check points – 18

UAV Ptero-G0

Gasoline engine

Max. take-off weight: 21 kg

Wing span: 3.13 m

Max. range: 800 km

Flight altitude: 80-3000 m

Max. flight time: 8 h

SpecificationsNikon D 800

CMOS sensor

Sensor size: 7360x4912 pix

Focal length: 50 mm

Phys. pixel size: 4.9 mkm

Two-curtain shutter

Calibration parameters

Project

 

Nikon D 800

Calibration methods W/O calibration Lab calibration

Self-calibration (Phys)

Lab calibration + phys self-calibration

Self-calibration (Mix)

Lab calibration + mix self-calibration

Focal length mm 50.0000 51.8813 50.4456 51.8455 50.2836 52.1451

Principal point (PPA, PPS)

X, mm 0.0000 0.0284 -0.0009 0.0233 -0.0005 0.0234

Y, mm 0.0000 0.2346 0.0075 0.2350 0.0041 0.2357

Distortion

K1 0.0000 -4.65806e-05 -4.64451e-05 -4.55496e-05 -3.02973e-05 -2.99335e-05

K2 0.0000 2.2396e-08 2.4015e-08 2.3189e-08 2.3232e-08 2.3633e-08

K3 0.0000 0.0000 2e-12 2e-12 2e-12 2e-12

Test № 3

250 m (GSD-7 cm)

Sony NEX 5N (f-16 mm)

Ground control points – 87, check points – 15

UAV Geoscan 101

Electric engine

Max. take-off weight: 2.3 kg

Wing span: 1.4 m

Max. range: 80 km

Flight altitude: 120-1000 m

Max. flight time: 1.5 h

SpecificationsSony NEX 5N

CMOS sensor

Sensor size: 4912x3264 pix

Focal length: 16 mm

Phys. pixel size: 4.9 mkm

Two-curtain shutter

Calibration parameters

Project

 

Sony NEX 5N

Calibration methods W/O calibration Lab calibration

Self-calibration (Phys)

Lab calibration + phys self-calibration

Self-calibration (Mix)

Lab calibration + mix self-calibration

Focal length mm 16.0000 16.1589 16.1684 16.3327 16.1150 16.2725

Principal point (PPA, PPS)

X, mm 0.0000 0.0073 0.0002 0.0083 0.0015 0.0109

Y, mm 0.0000 0.0097 0.0042 0.0114 0.0099 0.0193

Distortion

K1 0.0000 -0.000281494 -0.000285462 -0.000282905 -0.000186768 -0.000186017

K2 0.0000 1.56364e-06 1.5992e-06 1.5789e-06 1.56374e-06 1.55695e-06

K3 0.0000 0.0000 -5e-12 -4e-12 -4e-12 -4e-12

Distortion plotting (Lab calibration)

Distortion plotting (Phys self-calibration)

Distortion plotting (Mix self-calibration)

Distortion plotting (3D)

Results analyzing (test № 1)

Project

 

600 m (GSD 4 cm) 800 m (GSD 6 cm)

Calibration methods

W/O calibratio

n (m)

Lab calibration

(m)

Self-calibration (Phys)

(m)

Lab calibration

+ phys self-

calibration (m)

Self-calibration (Mix) (m)

Lab calibration + mix self-calibration

(m)

W/O calibration

(m)

Lab calibratio

n (m)

Self-calibrati

on (Phys)

(m)

Lab calibration + phys self-calibration

(m)

Self-calibration (Mix)

(m)

Lab calibration +

mix self-calibration

(m)

Check pointsRMSXY 0.408 0.125 0.195 0.071 0.065 0.066 0.418 0.075 0.289 0.077 0.065 0.077

Z 1.965 0.137 0.256 0.101 0.109 0.115 1.941 0.083 0.445 0.071 0.102 0.080

W/O

calib

ratio

n

Lab

calib

ratio

n

Self-

calib

ratio

n (P

hys)

Lab

calib

ratio

n + p

hys se

lf-ca

libra

tion

Self-

calib

ratio

n (M

ix)

Lab

calib

ratio

n + m

ix se

lf-ca

libra

tion

0

0.1

0.2

0.3

0.4

600 m800 m

0

0.5

1

1.5

2

2.5

600 m800 m

ZXY

Phase One IXU 150 (f-55mm)

Results analyzing (test № 2, 3)

Project

 

Nikon D 800 (GSD 4 cm) Sony NEX 5N (GSD 5 cm)

Calibration methods

W/O calibratio

n (m)

Lab calibration

(m)

Self-calibration (Phys)

(m)

Lab calibration

+ phys self-

calibration (m)

Self-calibration (Mix) (m)

Lab calibration + mix self-calibration

(m)

W/O calibration

(m)

Lab calibratio

n (m)

Self-calibrati

on (Phys)

(m)

Lab calibration + phys self-calibration

(m)

Self-calibration (Mix)

(m)

Lab calibration +

mix self-calibration

(m)

Check pointsRMSXY 0.273 0.1 0.096 0.101 0.096 0.101 0.148 0.127 0.111 0.116 0.101 0.1

Z 2.279 0.168 0.223 0.138 0.222 0.123 1.063 0.352 0.15 0.165 0.132 0.125

XY

W/O

calib

ratio

n

Lab

calib

ratio

n

Self-

calib

ratio

n (P

hys)

Lab

calib

ratio

n + p

hys se

lf-ca

libra

tion

Self-

calib

ratio

n (M

ix)

Lab

calib

ratio

n + m

ix se

lf-ca

libra

tion

0

0.05

0.1

0.15

0.2

0.25

0.3

Nikon D800Sony NEX 5N 0

0.5

1

1.5

2

2.5

Nikon D800Sony NEX 5N

Z

Image quality

Nikon D800 (GSD-5cm) Sony NEX 5N (GSD-5cm)

Conclusions

Prerequisites for obtaining large scale orthophoto

For cameras with central shutter –

For cameras with two-curtain shutter –

XYMix self-

calibration

ZLab calibration +

mix self-calibration

XYMix self-

calibration

ZLab calibration +

mix self-calibration

Thank you for attention