Photogrammetry Lecture 2 - Surveying (3) 2024-2025 PDF

Civil Engineering Department Surveying (3) Second Year 2024-2025 Surveying (3) Photogrammetry CIV213 Lecture 2...

Civil Engineering Department Surveying (3) Second Year 2024-2025 Surveying (3) Photogrammetry CIV213 Lecture 2 Dr. Hala Hashem 1  Civil Engineering Department Surveying (3) Second Year 2023-2024 Outline In this lecture, you will learn about: Camera calibration Laboratory calibration Lecturer: Dr. Hala Hashem 2 Civil Engineering Department Surveying (3) Second Year 2023-2024 Camera calibration data Laboratory calibration method  Equivalent focal length (EFL)  Calibrated focal length (CFL)  Radial length distortion (RLD)  Coordinates of principle point  Distance between fiducial marks  Angles intersection of fiducial lines Lecturer: Dr. Hala Hashem 3 Civil Engineering Department Surveying (3) Second Year 2023-2024 Camera calibration data Laboratory calibration method Multicollimator  Consists of number of collimator fixed in a precise angular positions  Each collimator consists of lenses with across its plane infinite focus  Light rays carry the image of the crosses ,projected through the lens and come out parallel. Lecturer: Dr. Hala Hashem 4 Civil Engineering Department Surveying (3) Second Year 2023-2024 Camera calibration data Laboratory calibration method 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 E.F.L = tan 7.5 𝑔𝑔𝑔𝑔+𝑔𝑔𝑔𝑔+𝑔𝑔𝑔𝑔+𝑔𝑔ℎ 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 = 4 1 C.F.L = E.F.L - max −𝑣𝑣𝑣𝑣 − 𝑚𝑚𝑚𝑚𝑚𝑚 + 𝑣𝑣𝑣𝑣 2 Lecturer: Dr. Hala Hashem 5 Civil Engineering Department Surveying (3) Second Year 2023-2024 Example: The following data were obtained from the camera calibration process.  Compute Equivalent focal length  Radial distortion at the remaining angular distance Angle 7.5 15 22.5 30 37.5 45 Average measured distance 20.223 41.164 63.643 88.706 117.866 153.535 (mm)  Plot the radial distortion curve based on EFL  Compute the calibrated focal length and plot its distortion curve for these data 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 20.223 E.F.L = = = 153.6089 mm tan 7.5 tan 7.5 Lecturer: Dr. Hala Hashem 6 Civil Engineering Department Surveying (3) Second Year 2023-2024 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 20.223 E.F.L = = = 153.6089 mm tan 7.5 tan 7.5 (rm) Average measured (rth) calculated ɵ Dr=rm- rth distance (mm) theoretical distance (mm) 7.5 20.223 20.223000 0 15 41.164 41.159390 0.004609804 22.5 63.643 63.626904 0.016095647 30 88.706 88.686160 0.019839784 37.5 117.866 117.868282 -0.00228174 45 153.535 153.608935 -0.07393542 Radial length distortion based on (CFL) 0.04 0.03 0.02 distortion(mm) 0.01 0 0 20 40 60 80 100 120 140 160 180 -0.01 -0.02 -0.03 -0.04 -0.05 -0.06 7 Lecturer: Dr. Hala Hashem r(mm) Civil Engineering Department Surveying (3) Second Year 2023-2024 1 C.F.L = E.F.L - max −𝑣𝑣𝑣𝑣 − 𝑚𝑚𝑚𝑚𝑚𝑚 + 𝑣𝑣𝑣𝑣 = 153.5818876 mm 2 (rm) Average measured (rth) calculated ɵ Dr=rm-rth distance (mm) theoretical distance (mm) 7.5 20.223 20.219439 0.003560913 15 41.164 41.152143 0.011857245 22.5 63.643 63.615701 0.02729922 30 88.706 88.670544 0.03545585 37.5 117.866 117.847527 0.018472777 45 153.535 153.581888 -0.0468876 Radial length distortion based on (CFL) 0.04 0.02 distortion(mm) 0 0 20 40 60 80 100 120 140 160 180 -0.02 -0.04 -0.06 -0.08 r(mm) 8 Lecturer: Dr. Hala Hashem