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ACCURACY OF PHOTOMOD AERIAL TRIANGULATION, Ivan KATZARSKY, Vanya PETROVA

ACCURACY OF PHOTOMOD ACCURACY OF PHOTOMOD AERIAL TRIANGULATIONAERIAL TRIANGULATION

Ivan KATZARSKY, Vanya PETROVAIvan KATZARSKY, Vanya PETROVAGIS SOFIA Ltd., BulgariaGIS SOFIA Ltd., Bulgaria


• For evaluation the capacity of a digital photogrammetric system of specialimportance is the accuracy of the aerial triangulation

• An experiment in 4 variants in Photogrammetry Department at GISSOFIA Ltd. determines the accuracy of PHOTOMOD

INTRODUCTION


SOFIA SOFIA MUNICIPALITYMUNICIPALITY

Test areaTest area

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

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

low houses• Average height of the terrain above sea level: 750 m

Test area characteristics

Aerial photography


DELTASCANGeoSystem Scientific Production Enterprise12 μm pixel size

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

Land surveying

Scanning


General information

EXPERIMENT DESCRIPTION

• 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


Scheme of the experimental block


Experimented variants

• PHOTOMOD Montage Desktop• PHOTOMOD AT• PHOTOMOD Solver

Polynomial correction of 2nd degree in X, Y and Z axes are applied

Aerial triangulation by PHOTOMOD 4.2 modules

VariantsGroundcontrolpoints

Check pointsPictures

per 1 GCPPictures

per 1 ChP

I 25 11 4.2 9.5II 20 16 5.2 6.6III 15 21 7 5IV 10 26 10.5 4


The accuracy of aerial triangulation is evaluated by mean squaredifferences between geodetic and photogrammetric coordinatesof the ground control and check points

RESULTS

Accuracy on the terrain, based on ground control points

Mean square differences between geodetic andphotogrammetric coordinates of the ground control pointsVariants

in X-axis in Y-axis in XY-plane in Z-axisI ± 3.3 cm ± 3.7 cm ± 5.0 cm ± 7.1 cmII ± 3.3 cm ± 3.4 cm ± 4.8 cm ± 5.5 cmIII ± 3.2 cm ± 3.5 cm ± 4.8 cm ± 4.8 cmIV ± 3.8 cm ± 1.1 cm ± 4.0 cm ± 2.3 cm


Accuracy on the terrain, based on check points

Mean square differences between geodetic andPhotogrammetric coordinates of the check pointsVariants

in X-axis in Y-axis in XY-plane in Z-axisI ± 4.5 cm ± 4.3 cm ± 6.3 cm ± 8.0 cmII ± 5.7 cm ± 5.7 cm ± 8.1 cm ±14.4 cmIII ± 6.5 cm ± 5.8 cm ± 8.7 cm ±14.4 cmIV ± 7.3 cm ± 9.3 cm ±11.8 cm ±26.7 cm


ANALYSISThe mean square differences between geodetic and photogrammetric

• In X-axis : ± 3.2 cm to ± 3.8 cm• In Y-axis : ± 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

co-ordinates of the ground control points are in the following range

The mean square differences between geodetic and photogrammetricco-ordinates of the check points are in the following range

• In X-axis : ± 4.5 cm to ± 7.3 cm• In Y-axis: ± 4.3 cm to ± 9.3 cm• In XY-plane: ± 6.3 cm to ± 11.8 cm• In Z-axis: ± 8.0 cm to ± 26.7 cm


CONCLUSIONS

• PHOTOMOD aerial triangulation, based on one ground control pointper 4 to 7 pictures, shows best result

• The results strongly depend on the experimental conditions andparameters. It gives an idea only for the capacity of PHOTOMODaerial triangulation. Another experiment could show other results

• Aerial triangulation carried out by PHOTOMOD shows a reliable accuracy


THANK YOU FOR YOUR ATTENTION!THANK YOU FOR YOUR ATTENTION!

Assoc. Prof. Dr. Ivan Katzarsky22 Omourtag StreetBG-1124 Sofia, BulgariaTel.: +359 (0)2 8466953GSM: +359 (0)88 [email protected]

Vanya Petrova, M.Sc.GIS SOFIA Ltd., Photogrammetry Dept.5 Serdica Str., BG-1000 Sofia, BulgariaTel.: +359 (0)2 9238338; 9307946GSM: +359 (0)88 [email protected]

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ACCURACY OF PHOTOMOD AERIAL ... - Semantic Scholar