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Introduction to Micro-Triangulation

Introduction to Micro-Triangulation. PACMAN meeting, CERN - Geneva, 26 May 2014. Vasileios VLACHAKIS. Introduction to Micro-Triangulation. Outline. Principle of triangulation Historical triangulation s Precision at the level of microns QDaedalus System Hardware - Instrumentation

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Introduction to Micro-Triangulation

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  1. Introduction to Micro-Triangulation PACMAN meeting, CERN - Geneva, 26 May 2014 Vasileios VLACHAKIS

  2. Introduction to Micro-Triangulation Outline • Principle of triangulation • Historical triangulations • Precision at the level of microns • QDaedalus System • Hardware - Instrumentation • Software - Algorithms • Past results at CERN • Future developments PACMAN meeting, CERN – Geneva, 26 May 2014

  3. Introduction to Micro-Triangulation Principle of triangulation Measurements / Observations: • Distances (in order to fix the scale) • Directions (w.r.t. the horizontal plane) • Angles (as differences of directions) • Horizontal • Vertical or Zenith Zenith V Hz Calculations / Estimations: • Distances (Unknown/Unmeasured) • Angles (Unknown/Unmeasured) + Coordinates w.r.t a reference system/frame ATLAS Network measurements (LS1 - Feb 2014) PACMAN meeting, CERN – Geneva, 26 May 2014

  4. Introduction to Micro-Triangulation Principle of triangulation As the Triangulation Network expands… • Incompatibility between Observations and Calculations! • Variation between repeated Observations! PACMAN meeting, CERN – Geneva, 26 May 2014

  5. Introduction to Micro-Triangulation Principle of triangulation Incompatibilitybetween Theory and Observations: Closure residuals • a+b+c≠ 180° or 200g or π [degrees] [grads/gons] [rads] • c+ d+ e+ f≠ 360° or 400gor2π Variation between repetitive Observations: • Environment → better control • Instrumentation → more precise + accurate • Observer → better to avoid him! b d e c f a Problem in Theoretical Model? OR / AND in Observations? PACMAN meeting, CERN – Geneva, 26 May 2014

  6. Introduction to Micro-Triangulation Principle of triangulation Problem: As the Triangulation Network expands… …the errors propagate + accumulate! PACMAN meeting, CERN – Geneva, 26 May 2014

  7. Introduction to Micro-Triangulation Principle of triangulation • Solution: • Measurements: • Sufficient • Repeated • Redundant • Adjustment of observations: • Least Squares Adjustment • BLUE (Best Linear Unbiased Estimation) PACMAN meeting, CERN – Geneva, 26 May 2014

  8. Introduction to Micro-Triangulation Evolution of angle measuring instruments Dioptra Heron of Alexandria (10-70 CE) Theodolite Jesse Ramsden (1735-1800) • Dimensions: 540x720x550 mm • Weight: 28kg • Accuracy: 20’’ - 60’’ Total Station Leica Geosystems (1996) • Dimensions: 220x350x180 mm • Weight: 7.5kg • Accuracy: 0.5’’ http://www.makingthemodernworld.org.uk/icons_of_invention/science/1750-1820/IC.014/ http://www.samosin.gr/exhibition/exhibits_uk.html 8 PACMAN meeting, CERN – Geneva, 26 May 2014

  9. Introduction to Micro-Triangulation Measuring the Meter! Before the French Revolution, about 250,000 units of length and weight exist in France • Pierre François André Méchain (1744-1804) and Jean Baptiste Joseph Delambre(1749-1822) measured the meridian arc Dunkerque-Paris-Barcelona • This effort took place during the period from 1792 to 1799 • “The meter" was defined as 1/10,000,000 of the distance North Pole - Equator. • The metric system was to be "pour tous pour toujours" “Repeating circle” of Jean-Charles de Borda (1733 -1799 ) http://pahar.in/survey-of-india-report-maps/ http://www.noa.gr/museum/english/organo_32_en.html 9 PACMAN meeting, CERN – Geneva, 26 May 2014

  10. Introduction to Micro-Triangulation Measuring Earth's highest mountain Great Trigonometric Survey (19th century) • Colonel William Lambton established the mission in 1802 • George Everest took leadership in 1823 • Andrew Scott Waugh replaced Everest as Surveyor-General in 1843 • Mount Everest was calculated (1852, published 1856) to be exactly 29000 ft / 8839.2 m high • Current high 29029 ft / 8848 m • Error of 9.5 cm in a baseline of 11.6 km (≈ 8ppm) http://pahar.in/survey-of-india-report-maps/ 10 PACMAN meeting, CERN – Geneva, 26 May 2014

  11. Introduction to Micro-Triangulation Micro-triangulation Principle of triangulation: Measurements / Observations: • Distances (in order to fix the scale) • Directions (w.r.t. the horizontal plane) • Angles (as differences of directions) Calculations / Estimations: • Distances (Unknown/Unmeasured) • Angles (Unknown/Unmeasured) +Coordinates w.r.t a reference frame Precision in level of micrometers: • Total Station precision ≈ 0.00015g or 1.5 cc • Precision of 2.4μm/m • Precision at 4 m < 10 μm ds = R ∙ dφ dφ ≈ 1.5 cc PACMAN meeting, CERN – Geneva, 26 May 2014

  12. Introduction to Micro-Triangulation QDaedalus Measurement System: • Developed at ETH Zürich (Geodesy and Geodynamics Lab) • Performs contactless, automatic, high precision measurements • Originally developed for rapid and easy determination of astronomical φ, λ, Α • Successor of ICARUS • Low-cost, non-destructive upgrade for automated theodolites (or total stations) • Composed of both, hardware and software developments PACMAN meeting, CERN – Geneva, 26 May 2014

  13. Introduction to Micro-Triangulation The basic idea How it works? • The operator’s eye is replaced by a CCD camera • Non-destructive way • Easily and rapidly mount • A software reads out the image and the angles • Angle measurements obtained faster and more precise What could be the precision? • Optical system resolution ≈ 4 arcsec/pixel • Object extraction ≈ 1/10 pixel or better • The achievable precision ≈ 0.4 arcsec (1.2 cc) • Total Station precision ≈ 0.5 arcsec (1.5 cc) PACMAN meeting, CERN – Geneva, 26 May 2014

  14. Introduction to Micro-Triangulation Components - Hardware The complete system is composed by: • A Total Station / theodolite • TDA5005 by Leica Geosystems (1.5 cc) • A CCD camera • Guppy F-080C by Allied Vision Technologies (4.65 µm, 30 fps) • A steering device for the focus mechanism • P110 064 by Portescap • Interface box (CCD Triggering synchronization of multiple system) • A laptop with the software QDaedalus PACMAN meeting, CERN – Geneva, 26 May 2014

  15. Introduction to Micro-Triangulation Algorithms - Software Optical target recognition (OTR) and measurement: • Center of mass • Template least-squares matching • Circle matching • Ellipse matching Computer vision processing operations: • Image acquisition • Pre-processing (resampling, de-noising,…) • Feature extraction (lines, circles, regions,…) • Segmentation • High-level processing (compute center, size,...) • QDaedalus is developed in C++ on the open source development platform Qt • Qt allows fast creation of cross-platform programs with a graphical user interface • The image processing algorithms are based on the open-source library OpenCV • The management of the data is based on the database engine SQLite PACMAN meeting, CERN – Geneva, 26 May 2014

  16. Introduction to Micro-Triangulation Main features Feature w.r.t. space/time resolution: • Density of points • Precision and Accuracy • Physical materialization of points • Sampling rate of measurements Other important features have to be considered: • Automation degree • Palpate / touchless • Measurement range • Transportability • Easy handling • Price PACMAN meeting, CERN – Geneva, 26 May 2014

  17. Introduction to Micro-Triangulation CLIC module application Automatic Micro-triangulation: • Import of approximate positions of station and targets • Definition of camera, focus, image processing parameters • Start of measurements, fully automatic process Source: Sébastien Guillaume PACMAN meeting, CERN – Geneva, 26 May 2014

  18. Introduction to Micro-Triangulation Measurement of May 2012 Targets: • 9 fixed and illuminated spheres of Ø8 mm Comparison: • CMM with a precision of 6 μm MPE • After 3D Helmert transformation Results: • 1.5 cc, horizontal direction • 1.5 cc, zenithal angles 18 PACMAN meeting, CERN – Geneva, 26 May 2014

  19. Introduction to Micro-Triangulation Future developments Hardware • Instrumental precision is sufficient • Wireless transmission of data and image triggering capabilities • Size reduction would be welcome (easier mechanical adaptation of the camera to the telescope) • Higher acquisition (frame) rates, up to 50 Hz Software • Synchronous steering of several total stations • Detection algorithm for an oscillating stretched wire and new fiducials Targets • Develop and evaluate different types of fiducials, compatible with FSI • Method of marking points on the stretched wire 19 PACMAN meeting, CERN – Geneva, 26 May 2014

  20. Introduction to Micro-Triangulation References • Bürki, B., Guillaume, S., Sorber, P., Oesch, H.-P. (2010). DAEDALUS: A versatile usable digital clip-on measuring system for Total Stations. International Conference on Indoor Positioning and Indoor Navigation (IPIN), Zürich, IEEE. • Griffet, S. (2010). Evaluation des performances du prototype de Micro-Triangulation. Survey report EDMS Document No 1106507, Genève, CERN. • Guillaume, S., Bürki, B., Griffet, S., Mainaud-Durand, H. (2012).QDaedalus: Augmentation of Total Stations by CCD Sensor for Automated Contactless High-Precision Metrology. FIG Working week 2012 Proceedings. • Schmid, M., Wanner, M., Manyoky, M. (2010). Suitability of the Daedalus System for Micro-triangulation. Geodetic Project Course, Geomatics Engineering and Planning. • Waniorek, S. (2011). Automatic Micro-triangulation. Survey report EDMS Document No 1152343, Genève, CERN. PACMAN meeting, CERN – Geneva, 26 May 2014

  21. Introduction to Micro-Triangulation Summary • Triangulation is a very old technique • Useful to obtain geometrical information • In short distances it is able to be precise at micrometer level • Changing the eye-piece with CCD we avoid the observer • Non-destructive upgrade of common Total Stations • Full exploitation of angle measurement precision at short distances (1-4 m) • The precision can be well predicted and it is completely depended on the configuration of the Micro-triangulation network • Developments needed in software, targets and hardware PACMAN meeting, CERN – Geneva, 26 May 2014

  22. Thank you! ?

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