Presentation on theme: "Technical assistance from Republic of Latvia offered to Iraq in the field of architectural sites documentation by photogrammetrical methods Mr. G.Goldbergs."— Presentation transcript:
1Technical 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
2Aim 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
3The main steps of creation of orthoimages camera calibrationmake the geodetical network to measure the controlmarks on the objecttake the photographyimage triangulationdigital surface model (DSM) creation and editingorthophoto creationpost processing of the data (vectorizing)
4DSM Evaluation of all the geometric distortions Two Dimensional AdjustmentInterior OrientationDistortionOriginal ImageFiducial MarksControl PointsCamera CalibrationResultsPhototriangulationrectification of imagesDSMOriginal ImageProjectionOrthophotoFlow Chart for Digital Orthophoto
5The technical equipment and software digital camera with tripodtotal station with tripodreflecting sheets and reflecting prismgeodetical network adjusting softwarecamera calibration software or camera calibration test fieldclose range photogrammetrical software
6Camera calibration- 2D dimensions calibration grid particular softwarePhotoModeler Pro 5.0 (Canada)- 4Mpix non-metric digital camera Olympus C-765Z.
7Instability 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 pixelsShorter focal length of digital camera – larger instability of interior parametersNecessary to perform camera calibration before each project (photo session)
9Geodetic 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.
15Digital 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:
16Digital Surface model (DSM) - elevation matrix for part of the wall
19Documentation 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 programsFusion of the results of geodetic survey, 3D laser scanner, photogrammetric and post-processing dataThe joint CAD model may be used to derive all required plans, models, or visualizations.
21ConclusionsAmateur 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.
22Mr. J.Kletnieks, Mr. B.Deslandes, UNESCO, LiteratureBirute Ruzgiene, Vilnius Technical University. Performance evaluation of non-metric digital camera for photogrammetric application. Geodesy and cartography,2005, Vol XXXI,No1Albert 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