1. Technical assistance from Republic of Latvia offered to Iraq in the field of architectural sites documentation by photogrammetrical methods Mr. G.Goldbergs Mr. M.Kalinka  Riga Technical University

2. Aim of training programme
To show and to learn in practice the combination a modern total station and a non-metric digital camera to derive digital orthoimages of architectural objects
- Digital orthoimages provide most of the geometric and radiometric information required for documentation of facades

3. The main steps of creation of orthoimages
camera calibration
make the geodetical network to measure the controlmarks on the object
take the photography
image triangulation
digital surface model (DSM) creation and editing
orthophoto creation
post processing of the data (vectorizing)

4. DSM Evaluation of all the geometric distortions Two Dimensional
Adjustment
Interior Orientation
Distortion
Original Image
Fiducial Marks
Control Points
Camera Calibration
Results
Phototriangulation
rectification of images
DSM
Original Image
Projection
Orthophoto
Flow Chart for Digital Orthophoto

5. The technical equipment and software
digital camera with tripod
total station with tripod
reflecting sheets and reflecting prism
geodetical network adjusting software
camera calibration software or camera calibration test field
close range photogrammetrical software

6. Camera calibration
- 2D dimensions calibration grid particular software
PhotoModeler Pro 5.0 (Canada)
- 4Mpix non-metric digital camera Olympus C-765Z.

7. Instability of the iterior orientations parameters using PhotoModeler Pro 5.0
RMS f(c)= 0,026 mm RMS xp = 0, RMS yp = 0,009 mm
~ 11 pixels ~7 pixels ~4 pixels
Shorter focal length of digital camera – larger instability of interior parameters
Necessary to perform camera calibration before each project (photo session)

8. Mosque of Ahmed Ibn Tulun, Cairo, Egypt

9. Geodetic network and control marks field
The geodetic network is very important to measure the control marks of the objects and connect all measurements together for 3D modeling.
The final result of image triangulation depends on the precision of the geodetic network and measuring methods of the control marks.
The special reflecting sheets on the white background are the best high precision technical material for putting the control marks.
To measure the control marks use the electronically tacheometry with minimum 5“ angle and 2 mm distance measuring precisions.
For training, we used the special SOKKIA reflector sheets and electronic tachometer SET 310.

10. Geodetic network and control marks field

12. Photography. The normal case geometry
B - photography base
m – image scale
D – distance between camera and object
c – focal length
l – image size

13. Phototriangulation
6 signalized control points in four stereo models.

14. Phototriangulation

15. Digital Surface model (DSM)
In architectural photogrammetry the relation between object height differences and distance between camera and object is much bigger than in aerial photogrammetry.
The errors in the digital surface models have a larger influence on the accuracy of the produced orthoimages, than in aerial photogrammetry.
- The DSM was created using vectors and breaklines vectorized manually:

16. Digital Surface model (DSM)
- elevation matrix for part of the wall

17. Orthophoto creation (mosaic)

18. Orthophoto
1 pixel = 5 mm

19. Documentation of cultural heritage
There are many various kinds of the documentation:
- orthophoto of the parts of objects
- 3D model with pictures
- 2D model of the object geometry in CAD programs
Fusion of the results of geodetic survey, 3D laser scanner, photogrammetric and post-processing data
The joint CAD model may be used to derive all required plans, models, or visualizations.

20. More results
north_centre_part west_centre_part

21. Conclusions
Amateur digital non-metric cameras under certain limited accuracy requirements can be used for wide low-accuracy photogrammetric purposes eg. buildings documentation etc.
The amateur digital cameras with number of pixels equal or more than 5 Mpix are well suited for photogrammetric purposes.
To minimize Y coordinates errors, the image overlapping should be > 65%
The orthoimages and its digital surface models (DSM) are fastest way to provide most of the geometric and radiometric information required for the documentation of architectural /archaeological sites.
Defining and signalizing of control points and knowing coordinates of image projective centers could improve the accuracy of image triangulation.

22. Mr. J.Kletnieks, Mr. B.Deslandes, UNESCO,
Literature
Birute Ruzgiene, Vilnius Technical University. Performance evaluation of non-metric digital camera for photogrammetric application. Geodesy and cartography,2005, Vol XXXI,No1
Albert Weidemann, Technical Univercity of Berlin, Digital orthoimages in architectural photogrammetry using digital surface models.
Special Thanks To:
Mr. J.Kletnieks, Mr. B.Deslandes, UNESCO,
Government of the Republic of Latvia, State Land service of Latvia, Riga Technical Univercity

23. Thank You for Attention !