Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 1Meeting with NCSX, Greifswald, 10.10.2007
Application of Photogrammetry during Construction of W7-X
T. Bräuer
Content: How Photogrammetry works?
Photogrammetry Equipment at IPP Greifswald
Examples of Photogrammmetry
Summary, Conclusion
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 2Meeting with NCSX, Greifswald, 10.10.2007
How Photogrammetry works?
Part 1: Principle
1. Taking a picture from a first camera position
2. Calculation of first camera position from points known (4 pieces; green lines) in the initial co-ordinate system (blue)
3. Calculation of line of sight to New-Points (red lines)
4. Taking pictures from additional camera positions
5. Repetition of step 2 & 3 for the additional camera positions
6. Calculation of the cross section of the line of sights to a New-Point and calculation of the 3-D co-ordinate
7. Finally: Bundle Block Adjustment
Position 1 Position 2 Position 3
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 3Meeting with NCSX, Greifswald, 10.10.2007
How Photogrammetry works?
Part 2: Marking of Points
• Signalization is made by retro reflex targets
• Surface points: retro reflective foils (sticky foil) Ø=10mm
• Primitive geometries: Adapter for
• Fitted holes• edges• corners• …
Adapter for fitted holes Ø=8mmH7 with retro reflex target
Surface point: Retro reflex foil Ø=10mm
Photogrammtry camera with ring flash
Example picture of retro reflective targets with its very high contrast
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 4Meeting with NCSX, Greifswald, 10.10.2007
How Photogrammetry works?
Part 3: Identify target points with numbers
• Each object point has to has the same number in all pictures!
• Coded points are recognized by software image processing
• Starting from a minimum of 6 coded points per picture it is possible to name all New-Points of a picture unique
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 5Meeting with NCSX, Greifswald, 10.10.2007
Photogrammetry-Equipment at IPP Greifswald
Measurement system:• 2 x Camera Nikon DX1 with ring flash 24mm lense 20mm lense• 1 x initial cross• 2 x scale bars 1390mm• 512 x coded targets
Software: • AICON 3D-Studio with• Image analysis and co-
ordinate calculation• Deformation analysis
Targets:• Sticky foil Ø=10mm for surface
• Targets for Ø=8H7 holes
HUBBs-targetsCrossing pointwith Offset (usually 25mm)vector-targetsball-targets
3-point-targets
feature-targets
1.5”-CCR-equivalent
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 6Meeting with NCSX, Greifswald, 10.10.2007
Examples of Photogrammetry
Part 1: Incoming inspection of a coil
Planarstütze 1Standfuß 2
Standfuß 1
Montagestütze 1 u. 2
Druckstütze 2
Zentralstütze 1 u. 2
Messpunkte
Ca. 3.5m
Coil and its Ref.-points
Survey of coil with Photogrammetry and Laser.Tracker
Ca. 150 New-Points per coil
Comparison Photogrammetrie and Laser-Tracker:
• 12 reference points• RMS = 0.118 mm
Installation of Photogrammetry targets
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 7Meeting with NCSX, Greifswald, 10.10.2007
Examples of Photogrammetry
Part 2: Survey of coils in assembly stand
• ≈ 480 pictures necessary
• 83% resp. 95% of points of a coil are visible
• Transformation into assembly stand resp. coils co-ordinate system
RMS = 0.13 mm
• Maximum position deviation
< 1.2 mm
• proof, that measurement accuracy required can be reached
• proof, that adjustment accuracy required can be reached
Photogrammetry at WENDELSTEIN 7-XUnternehmung
WENDELSTEIN 7-X
Max-Planck-Institut für Plasmaphysik
Torsten Bräuer 8Meeting with NCSX, Greifswald, 10.10.2007
Summery / conclusion
• Repetition measurement uncertainty of Photogrammetry is better than 0.1…0.15mm in a volume of 5x5x5m³
• Photogrammetry is appropriated for complex components with a high number of target points
• A high number of target points on a component means a high probability to get enough lines of sight
• Photogrammmetry do not need rigid stand points for the measurement system
• For 4 or more coils assembled in assembly stand Photogrammetry needs less on-line time for a survey than other survey technique (for instant Laser-Tracker)
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• Photogrammmetry needs off-line post processing time
• Adjustment off components using Photogrammetry needs a lot of affords or is impossible
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