1. Calibration of the Nikon D200 for Close-Range Photogrammetry
Lassana Sheriff
Office of Science, Science Undergraduate Laboratory Internship Program
City College of New York, New York NY
SLAC National Accelerator Laboratory, Menlo Park, California
August 13, 2009

2. Outline (AEG) and Metrology Department Camera (Nikon D200)
Software and Targets
Camera Model
Central Perspective Projection
Brown Extension Model
2D Calibration Wall
3D Calibration Structure
Results
Conclusion and Future
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3. Alignment Engineering Group (AEG) and Metrology Department
Measuring and Aligning objects with survey instruments (Laser Tracker)
For instance: Magnets and other components in LCLS from the electron gun to the dump
The project is to evaluate the possibility to use photogrametry as another survey technique
Photogrametry: Photographic Metrology
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4. Camera Nikon D200 and built-in flash. DX format 23.7mm x 15.7mm
10.2 megapixels(6 micron square pixels)
Nikkor 20mm lens
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5. Software and Targets Australis
Coded Targets (Retro-reflective) 60 degree lose reflective property.
Scale Bar (Distance between the targets on the bar is known) can use to scale measurement
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6. Reflective Targets Coded Spherical targets Rotatable targets
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7. Object co-ordinate system
Image point m x Y p r yp o xp X c i
Projection plane Z C i
Perspective center Z Y M
Object point X O
Object co-ordinate system
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8. Camera Parameters Interior Orientation of the Camera
Focal length and the principal points of the camera: c, xp, and yp
Extended by Brown Model
k1,k2,k3 (radial distortion)
p1, p2 (decentering)
b1, b2 (shearing)
Compare, analyze and assess the camera’s stability
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9. Interior Orientation
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10. Central Perspective Projection
This equation illustrates an ideal basic photogrammetry model
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11. 2D wall One partial wall in AEG Laboratory Coded Targets
13 points measured with a laser tracker
Different Angles
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12. Flat Wall without Processing
No Australis
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13. Australis window for the wall
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14. 3D 3D Structure Coded Targets Reflective Sphere Same Angles as 2D
Started late
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15. 3D without Processing No Australis August 13, 2009
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16. Graphs Line Graphs (trends) Histogram (distribution)
41 data sets 2D wall
6/29-8/7
23 data sets 3D structure
7/15-8/7
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17. Line Graph c
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18. Line Graph xp
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19. Line Graph yp
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20. Histogram c
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21. Histogram xp
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22. Histogram yp
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23. Results
Line Graphs and their purpose (No trend as data is scattered and good stability within the day)
Example: Focal length, some points are far off the trend likely due to transportation and handling purposes
Histogram (distribution of the parameters)
Normal Distribution
(xp and yp) alike and are not normally distributed
Focal length more like a normal distribution.
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24. Conclusion and Future
Camera can be used for Photogrammetry measurements but calibrate before each use.
Mechanical improvement to the camera
3D structure from more angles to get true 360 degree.
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25. Acknowledgement
The Science Undergraduate Laboratory Internship SULI program wouldn't have been possible without the funding of the Department of Energy DOE here at Stanford Linear Accelerator Center SLAC. Special acknowledgment goes to my mentor BRIAN FUSS for his diligent guidance and support. I would like to acknowledge CATHERINE LECOCQ for her resilient work and direction in the entire project. And finally acknowledgement to BRENDAN DIX for his participation in building the 3D structure; and to the rest of the members of Alignment Engineering Group for their support.
…and thanks to Stephen and all the students!!
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