Upload
allegra-mendez
View
68
Download
0
Embed Size (px)
DESCRIPTION
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 - PowerPoint PPT Presentation
Citation preview
Introduction to Micro-Triangulation
Vasileios VLACHAKIS
1
PACMAN meeting, CERN - Geneva, 26 May 2014
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
2
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
Introduction to Micro-Triangulation
3
Principle of triangulationMeasurements / Observations:•Distances (in order to fix the scale)•Directions (w.r.t. the horizontal plane)•Angles (as differences of directions)
– Horizontal– Vertical or Zenith
Calculations / Estimations:•Distances (Unknown/Unmeasured) •Angles (Unknown/Unmeasured)
+ Coordinates w.r.t a reference system/frameATLAS Network measurements (LS1 - Feb 2014)
Hz
V
Zenith
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
4
Principle of triangulation
As the Triangulation Network expands…•Incompatibility between Observations and Calculations!•Variation between repeated Observations!
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
5
Principle of triangulation
Incompatibility between Theory and Observations:Closure residuals•a + b + c ≠ 180° or 200g or π [degrees] [grads/gons] [rads]
•c + d + e + f ≠ 360° or 400g or 2π
Variation between repetitive Observations:•Environment → better control•Instrumentation → more precise + accurate•Observer → better to avoid him!
Problem in Theoretical Model? OR / AND in Observations?
a
bcd e
f
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
6
Problem:As the Triangulation Network expands…
…the errors propagate + accumulate!
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
Introduction to Micro-Triangulation
7
Principle of triangulation
8
Evolution of angle measuring instruments
DioptraHeron of Alexandria (10-70 CE)
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
TheodoliteJesse Ramsden (1735-1800)•Dimensions: 540x720x550 mm•Weight: 28kg •Accuracy: 20’’ - 60’’
Total StationLeica Geosystems (1996)•Dimensions: 220x350x180 mm•Weight: 7.5kg •Accuracy: 0.5’’
http://www.samosin.gr/exhibition/exhibits_uk.html
http://www.makingthemodernworld.org.uk/icons_of_invention/science/1750-1820/IC.014/
9
Measuring the Meter!
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
Before the French Revolution, about 250,000 units of length and
weight exist in France
http://pahar.in/survey-of-india-report-maps/http://www.noa.gr/museum/english/organo_32_en.html
“Repeating circle” of Jean-Charles de Borda (1733 -1799 )
• 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"
10
Measuring Earth's highest mountain
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
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/
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
11
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
Micro-triangulationPrecision in level of micrometers:
•Total Station precision ≈ 0.00015g or 1.5 cc•Precision of 2.4μm/m•Precision at 4 m < 10 μm
dφ ≈ 1.5 cc
ds = R d∙ φ
12
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
Introduction to Micro-Triangulation
13
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
Introduction to Micro-Triangulation
14
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
Introduction to Micro-Triangulation
15
• 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
Algorithms - Software
Optical target recognition (OTR) and measurement:1.Center of mass
2.Template least-squares matching
3.Circle matching
4.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,...)
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
16
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
Introduction to Micro-Triangulation
17
CLIC module application
Automatic Micro-triangulation:1.Import of approximate positions of station and targets
2.Definition of camera, focus, image processing parameters
3.Start of measurements, fully automatic process
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
Source: Sébastien Guillaume
18
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 transformationResults:•1.5 cc, horizontal direction•1.5 cc, zenithal angles
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
19
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
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
20
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
Introduction to Micro-Triangulation
PACMAN meeting, CERN – Geneva, 26 May 2014
Introduction to Micro-Triangulation
21
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
Thank you!
?
22