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A comparison of the performance of various digital aerial photography systems

in an aerial surveys of large territories

Sergey KadnichanskiyChief Technologist

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Survey of large territories, counted in the thousands, tens and hundreds of thousands of square km, is usually carried out for the creation or updating of maps of scale1:2000 -1:25000 depending on the nature of the territory

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Under performance of aerial survey system is understood as the area of the territory, aerial photography of which is performed in a unit of time. It is expedient to relate this area to one hour of flight time

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Performance can be considered only in relation to certain conditions:

• the type and characteristics of the aircraft

• specific requirements to aerial photography

- the scale of the map (plan) - the appointment of the aerial survey

and the specific constraints to effective

angle of the field of view of aerial camera

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The scale of the map sets the required spatial resolution of aerial photo defined, as a rule, as the ground pixel size

Map scale Range of recommended ground

pixel size (cm)

Average ground pixel size (cm)

1:2000 14-22 18

1:5000 30-40 35

1:10000 40-60 50

1:25000 70-90 80

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Under the effective angle of the field of view will understand, angle, limiting the part of aerial photo image in the cross on the line of flight direction, which will be directly used in the end product, for example orthophoto

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The effective angle β of the field of view is associated with the distance between the flight lines By and the height of flight H

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Nature of the territory β f Map scales

Urban areas 30° 30 сm1:2000, 1:5000

Open territory 53° 15 сm1:10000, 1:25000

Analog aerial survey with camera 23 x 23 cm Side overlap 30% ; f=15 cm; f=30 cm

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The effective image size is the number of pixels corresponding to the effective field of view β

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Effective Image Size

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Research and production aerial survey and geodetic company "Meridian+" owns and uses in its work aerial survey systems of fundamentally different type, which can be effectively used for surveying large areas

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Frame digital mapping aerial cameras

DMC (Z/I Imaging)

Size of final image pan-sharpened RGB or CIR image

along track 7680 pix cross track 13824 pix

Field of view along track 42.0°cross track 69.3°

Focal length of final image 120 mm Pixel size 12 μм

Multispectral cameras Red; Green; Blue; NIR

Size of multispectral images 3000 х 2000 pix Maximum frame rate 2 sec/image Radiometric resolution 12 bit

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Aerial survey system with CCD linear arrays

ADS40 (Leica Geosystems)

Field of view along track 64°

Focal length 62.8 mm

Recording interval per line 1.2 ms

Pixel size 6.5 μm

Size of CCD array 12000 pix

Radiometric resolution 12 bit

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Scanning aerial survey system with CCD matrixes

А3 (VisionMap)Focal length 300 mmPixel size 9 μmField of view of CCD camera along track cross track

6.58°4.58°

Max of camera rotation angle 104°Capacity memory (frames) 250 000 Size of frame image 7812*2666

pixSize of final RGB image along track cross track

~8000 pix~60000 pix

Max field of view of final image along track cross track

13.47° 108°

Radiometric resolution of original image 12 bit

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The productivity aerial survey systems is largely supported by the use of a specially equipped for aerial photography aircraft King Air 350, (Beechcraft)

Max flight altitude for aerial survey

9500 m

Max speed 578 km/hr

Average speed 439 km/hr

Min speed 250 km/hr

Flight time 5.2 hr

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Next will be the analysis of performance for the above listed cameras as well as new cameras DMCII 250 and UltraCam Eagle using the aircraft King Air 350

The most important characteristics of the camerasAerial Camera Cross track Size of Final image(pixels)

Cross track field of view (°)

Pixel Size (μm)

Angular Resolution (°)

DMC 13824 69.3 12 0.0054ADS40 12000 64 6.5 0.0056A3 ~95000 108 9.0 0.0017UltraCam Eagle 80 20010 66.1 5.2 0.0037UltraCam Eagle 210 20010 27.8 5.2 0.0014DMCII 250 17216 46.5 5.6 0.0029

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The productivity of aerial survey for area 2500 кm2 for map scale 1:2000 and effective field of view ≤30° , including turns and transit flights

Aerial Camera

GSD (сm)

Flying Height, m

Side Overlap

Time Consumption, hr/day

Produc-tivity, km2/hr

Effective Size of Image, pixels

Effective field of view (°)

DMC 18 1800 61.0% 11.72/2.2 213 5391 30

ADS40 18 1739 56.5% 12.07/2.3 207 5220 30

A3 18 (17.44)

5813 69.4% 3.85/0.8 649 17554 30

UltraCamEagle 80

18 2769 58.8% 7.69/1.5 325 8244 30

UltraCamEagle 210

18 7269 30.0% 4.38/0.8 571 14007* 19.7

DMCII 250 18 3600 37.6% 6.26/1.2 399 10743 30

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The productivity of aerial survey for area 2500 кm2 for map scale 1:5000 and effective field of view ≤ 30° , including turns and transit flights

Aerial Camera

GSD (сm)

Flying Height, m

Side Overlap

Time Consumption, hr/day

Produc-tivity, km2/hr

Effective Size of Image, pixels

Effective field of view (°)

DMC 35 3500 61.0% 6.44/1.2 388 5391 30

ADS40 35 3382 56.5% 6.62/1.3 377 5220 30

A3 28.9 (28.0)

9333 81.0% 2.95/0.6 847 17554 30

UltraCamEagle 80

35 5385 58.8% 4.02/0.8 625 8244 30

UltraCamEagle 210

24 9288 30.0% 3.67/0.7 681 14007* 19.7

DMCII 250 35 7000 37.6% 3.31/0.6 756 10743 30

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The productivity of aerial survey for area 250000 кm2 for map scale 1:10000 and effective field of view ≤ 53° , including turns and transit flights

Aerial Camera

GSD (сm)

Flying Height, m

Side Overlap

Time Consumption, hr/day

Produc-tivity, km2/hr

Effective Size of Image,pixels

Effective field of view (°)

DMC 50 5000 30% 128.6/24.7 1943 9676 51.6

ADS40 50 4831 30% 148.5/28.6 1683 8400 47.0

A3 29.6 (28.00)

9333 64.8% 57.2/11.4 4371 31396 53.0

UltraCamEagle 80

50 7692 30% 89.6/17.2 2790 14007 48.9

UltraCamEagle 210

23 9288 30% 193.3/37.8 1293 14007 19.7

DMCII 250 46 9200 30% 112.6/21.7 2219 12051 33.5

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The productivity of aerial survey for area 250000 кm2 for map scale 1:25000 and effective field of view ≤ 53° , including turns and transit flights

Aerial Camera

GSD (сm)

Flying Height, m

Side Overlap

Time Consumption, hr/day

Produc-tivity, km2/hr

Effective Size of Image,pixels

Effective field of view (°)

DMC 80 8000 30% 80,7/15.5 3098 9676 51.6

ADS40 80 7729 30% 92.7/17.8 2696 8400 47.0

A3 29.6 (28.00)

9333 64.8% 57.2/11.4 4371 31396 53.0

UltraCamEagle 80

60 9231 30% 74.7/15.4 3348 14007 48.9

UltraCamEagle 210

- - - - - - -

DMCII 250 46 9200 30% 112.6/21.7 2219 12051 33.5

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When estimating the expenditure of time, have been used the following conditions of flight Speed 520 km/hr

Transit time from the airport 0.4 hr

Transit time to the airport 0.4 hr

Flight time 5.2 hr

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Productivity and Effective Image Size Map scale 1:2000, GSD=18 cm Aerial Camera Productivity,

km2/hr

Effective Size of Image,pixels

Relative Productivity

Relative Effective

Size of Image

GSD (cm)

DMC 213 5391 1 1 18ADS40 207 5220 0.97 0.97 18A3 649 17554 3.05 3.26 18UltraCamEagle 80

325 8244 1.53 1.53 18

UltraCamEagle 210

571 14007 2.68 2.60 18

DMCII 250 399 10743 1.87 1.99 18

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Productivity and Effective Image Size Map scale 1:10000, GSD=50 cm

Aerial Camera Productivity,

km2/hr

Effective Size of Image,pixels

Relative Productivity

Relative Effective

Size of Image

GSD (cm)

DMC 1943 9676 1 1 50ADS40 1683 8400 0.87 0.87 50A3 4371 31396 2.24 3.24 29.6UltraCamEagle 80

2790 14007 1.44 1.44 50

UltraCamEagle 210

- - - - -

DMCII 250 2219 12051 1.14 1. 24 46

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All mentioned aerial cameras provide

reception of stereo pairs of images for the stereoscopic interpretation and precise spatial measurements

Each of aerial cameras type has its advantages and opportunities

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DMC Spectral type of images: RGB,R,G,B, NIR

Absence of necessity in control points

Absence of necessity in aerial triangulation for scales1:5000 and 1:25000

Possibility of simultaneous execution of air laser scanning to capture DTM for spatial resolution photos ≤ 50 cm.

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ADS 40Spectral type of images: RGB,R,G,B, NIR

Absence of necessity in control points

Absence of necessity in aerial triangulation for scales1:5000 and 1:25000

Possibility of simultaneous execution of air laser scanning to capture DTM for spatial resolution photos ≤ 50 cm.

The possibility of obtaining options stereo pairs of images with differentratio В/Н

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А3

Spectral type of images: RGB

Absence of necessity in control points for scales 1:5000 и 1:25000

The highest performance of aerial survey

The spatial resolution is 28 cm (nadir) and limited by the flight altitude. Such high resolution provides higher image interpretation properties that makes possible to use the results of aerial survey in creation of maps at scale 1:2000 covering, for example inhabited localities

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Conclusions

Productivity of aerial survey of large territories is proportional to effective size of image in pixels provided by digital aerial camera

(for specified GSD)

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Conclusions

Modern digital aerial cameras provide high performance and efficiency of aerial survey, opportunities and significant advantages in aerial image processing for production of maps covering large areas

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Conclusions

250 000 km2 for map scales 1:5000, 1:10000

in 12 days !

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Thank you for your attention