ACCURACY OF PHOTOMOD AERIAL TRIANGULATION

Ivan KATZARSKY, Vanya PETROVA GIS SOFIA Ltd., Bulgaria

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

INTRODUCTION

• • For evaluation the capacity of a digital photogrammetric system of special importance is the accuracy of the aerial triangulation An experiment in 4 variants in Photogrammetry Department at GIS SOFIA Ltd. determines the accuracy of PHOTOMOD

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

TEST AREA

Test area characteristics

• • • • • • • • • • Area: 3103 hectares Terrain: flat, lightly hilly and hilly not dense urban area with predominantly

SOFIA

low houses

MUNICIPALITY

Average height of the terrain above sea level: 750 m

Aerial photography

Test area

Contractor: Hansa Luftbild Sensorik und Photogrammetry GmbH, Münster Execution of the photo-flight: 19.05.2006

Aircraft: Cessna 404 Titan Aerial camera: Zeiss RMK TOP 30/23 (Z/I Imaging) Overlap between the pictures: forward 60 %, side 30 % Aerial film: Kodak Aerocolor Negative 2444 III, 19 DIN Film processor: Colenta

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

Scanning

DELTASCAN GeoSystem Scientific Production Enterprise 12 μm pixel size

Land surveying

Pre-marked on the terrain ground control and check points, determined by GPS-receiver Topcon GGD with an accuracy of ± 2 cm in position and ± 3 cm in height

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

EXPERIMENT DESCRIPTION General information

• • • • • • • • • Blocks of aerial pictures……………………………………………….. 1 Strips of aerial pictures………………………………………………… 6 Aerial pictures…………………………… 14+17+18+18+19+19 = 105 Approximate picture scale…………………………………….. 1 : 4710 Average flight height above the terrain,

m

……………………… 1440 Ground pixel size,

cm

………………………………………………. 5.7

Pre marked points on the terrain……………………………………. 36 Pictures per 1 pre marked point……………………………………… 3 Tie points…………………………………………………………….. 786

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

Scheme of the experimental block

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

Experimented variants

Variants I II III IV Ground control points 25 20 15 10 Check points 11 16 21 26 Pictures per 1 GCP 4.2

5.2

7 10.5

Pictures per 1 ChP 9.5

6.6

5 4

Aerial triangulation by PHOTOMOD 4.2 modules

• • • PHOTOMOD Montage Desktop PHOTOMOD AT PHOTOMOD Solver Polynomial correction of 2nd degree in X, Y and Z axes are applied

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

RESULTS

The accuracy of aerial triangulation is evaluated by mean square differences between geodetic and photogrammetric coordinates of the ground control and check points

Accuracy on the terrain, based on ground control points

Variants I II III IV Mean square differences between geodetic and photogrammetric coordinates of the ground control points in X-axis ± 3.3 cm ± 3.3 cm ± 3.2 cm ± 3.8 cm in Y-axis ± 3.7 cm ± 3.4 cm ± 3.5 cm ± 1.1 cm in XY-plane ± 5.0 cm ± 4.8 cm ± 4.8 cm ± 4.0 cm in Z-axis ± 7.1 cm ± 5.5 cm ± 4.8 cm ± 2.3 cm ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

Accuracy on the terrain, based on check points

Variants I II III IV Mean square differences between geodetic and Photogrammetric coordinates of the check points in X-axis ± 4.5 cm ± 5.7 cm ± 6.5 cm ± 7.3 cm in Y-axis ± 4.3 cm ± 5.7 cm ± 5.8 cm ± 9.3 cm in XY-plane ± 6.3 cm ± 8.1 cm ± 8.7 cm ±11.8 cm in Z-axis ± 8.0 cm ±14.4 cm ±14.4 cm ±26.7 cm ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

ANALYSIS

The mean square differences between geodetic and photogrammetric co-ordinates of the ground control points are in the following range • • • • In X-axis : In Y-axis : ± 3.2 cm to ± 3.8 cm ± 1.1 cm to ± 3.7 cm In XY-plane : ± 4.0 cm to ± 5.0 cm In Z-axis : ± 2.3 cm to ± 7.1 cm The mean square differences between geodetic and photogrammetric co-ordinates of the check points are in the following range • • • • In X-axis : In Y-axis: In XY-plane: In Z-axis: ± 4.5 cm to ± 7.3 cm ± 4.3 cm to ± 9.3 cm ± 6.3 cm to ± 11.8 cm ± 8.0 cm to ± 26.7 cm

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

CONCLUSIONS

• PHOTOMOD aerial triangulation, based on one ground control point per 4 to 7 pictures, shows best result • The results strongly depend on the experimental conditions and parameters. It gives an idea only for the capacity of PHOTOMOD aerial triangulation. Another experiment could show other results • Aerial triangulation carried out by PHOTOMOD shows a reliable accuracy

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

THANK YOU FOR YOUR ATTENTION!

Authors

Assoc. Prof. Dr. Ivan Katzarsky 22 Omourtag Street BG-1124 Sofia, Bulgaria Tel.: +359 (0)2 8466953 GSM: +359 (0)88 5325509 [email protected]

Vanya Petrova, M.Sc.

GIS SOFIA Ltd., Photogrammetry Dept.

5 Serdica Str., BG-1000 Sofia, Bulgaria Tel.: +359 (0)2 9238338; 9307946 GSM: +359 (0)88 6067306 [email protected]

ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA