Photogrammetry at WENDELSTEIN 7-X Unternehmung WENDELSTEIN 7-X Max-Planck- Institut für Plasmaphysik Torsten Bräuer1Meeting with NCSX, Greifswald, 10.10.2007.

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


WENDELSTEIN 7-X



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


WENDELSTEIN 7-X




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


WENDELSTEIN 7-X




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


WENDELSTEIN 7-X



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


WENDELSTEIN 7-X



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


WENDELSTEIN 7-X



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


WENDELSTEIN 7-X



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

Photogrammetry at WENDELSTEIN 7-X Unternehmung WENDELSTEIN 7-X Max-Planck- Institut für Plasmaphysik Torsten Bräuer1Meeting with NCSX, Greifswald, 10.10.2007.

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