Depth from Focus
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− | + | [[Image:Dvcoin.png|thumb|240px|right||Extended depth-of-field image showing part of a 10-pence coin (compare with 1.39 MByte [http://vision.eng.shu.ac.uk/jan/coin.avi video of focus stack])]] | |
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− | |[[Image:grid_0055.jpg|thumb| | + | |[[Image:grid_0055.jpg|thumb|180px|First surfi-sculpt object, Leica DM LAM]]||[[Image:wheel_0136.jpg|thumb|180px|Second surfi-sculpt object, Leica DM LAM]]||[[Image:BrokenSuevit1_001500.png|thumb|180px|Piece of Suevit (enamel like material from meteorite impact) from the [http://en.wikipedia.org/wiki/Ries Nördlinger Ries], Leica DM RXA]]||[[Image:Hair20.png|thumb|180px|Micro-camera image of a hair on top of a laser printout]]||[[Image:Coin063.jpg|thumb|180px|Surface of 10-pence coin, Leica DM LAM]] |
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− | |[[Image:griddv.jpg|thumb| | + | |[[Image:griddv.jpg|thumb|180px|Extended depth of view for first object]]||[[Image:wheeldv.jpg|thumb|180px|Extended depth of view for second object]]||[[Image:SuevitDV.png|thumb|180px|Extended depth of view for Suevit (fringes have been removed manually)]]||[[Image:HairDV.png|thumb|180px|Extended depth of view for the hair]]||[[Image:Dvcoin.png|thumb|180px|Extended depth-of-field image showing part of the 10-pence coin (compare with 1.39 MByte [http://vision.eng.shu.ac.uk/jan/coin.avi video of focus stack])]] |
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− | |[[Image:grid1080.jpg|thumb| | + | |[[Image:grid1080.jpg|thumb|180px|3D reconstruction of first object [http://vision.eng.shu.ac.uk/jan/grid1.avi (742kB video)]]]||[[Image:wheel1008.jpg|thumb|180px|3D reconstruction of second object [http://vision.eng.shu.ac.uk/jan/wheel1.avi (725kB video)]]]||[[Image:suevit20.png||thumb|180px|3D reconstruction of suevit [http://vision.eng.shu.ac.uk/jan/suevit.mpg (1.4MB video)]]]||[[Image:Hair.png|thumb|180px|3D reconstruction of hair [http://vision.eng.shu.ac.uk/jan/hair.mpg (1.4MB video)]]]||[[Image:Coin.png|thumb|180px|3D reconstruction of 10-pence coin surface (profile is amplified 5 times)]] |
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− | |[[Image:Grid245.jpg|thumb| | + | |[[Image:Grid245.jpg|thumb|180px|Red-cyan anaglyph image of first object [http://vision.eng.shu.ac.uk/jan/grid.avi (2.0MB video)]]]||[[Image:Sugar.jpg|thumb|180px|Extended depth of field image for a piece of sugar (compare with 532 kByte [http://vision.eng.shu.ac.uk/jan/sugarstack.avi video of focus stack])]]||[[Image:Fiberdf10xdv.png|thumb|180px|Extended depth of field image of glass fibers (compare with 1.09 MByte [http://vision.eng.shu.ac.uk/jan/fiberdf10x.avi video of focus stack])]]||[[Image:SmallWheel.png|thumb|180px|Reconstruction of ''0.6 mm'' cogwheel using multiple focus sets]]|| |
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Revision as of 17:20, 3 November 2006
Contents |
Depth from Focus
3D surface metrology
- In principle it should work with any microscope, which has a motorized z-drive and a digital camera (see Mimas video input).
- The results will be even better, if the illumination optics of the microscope can project a pattern.
- Non-destructive measurement of surface profiles
- With our experimental settings we observed (of course the result will depend on the quality of the microscope)
- Vertical resolution <math>\ge 0.2\ \mu m</math> (depending on aperture-size, magnification, projection-pattern and the surface properties of the object).
- Lateral resolution <math>\ge 2\ \mu m</math> (depends).
- Open Source (you are free to improve the code yourself if you redistribute it).
In general one can say: The lower the depth of field, the higher the resolution of the reconstruction. With high magnification (assuming constant numerical aperture) the resolution of the reconstruction goes up. The trade-off is that the reconstruction will cover a smaller area. This could be overcome by lateral stitching (e.g. cogwheel below).
Demonstration
Here are some typical microscope images (showing a surface, which has been shaped using a power beam).
Using a focus-stack one can compute images with extended depth of focus:
If the surface can be illuminated properly, one can even do a 3D-reconstruction of the surface:
[[Image:suevit20.png | 180px|3D reconstruction of suevit (1.4MB video)]] |
As the idea for the algorithm was fixed already, it was possible to implement the algorithm as a command-line tool in less than 4 days, using existing Mimas-software (exspecially the operators for boost::multi_array).
As this is a "quick hack", there's still lots of space for improvements.
Download
The software for estimating height-maps and images with extended depth-of-field is available for free (under the LGPL)! You first need to install version 2.0 of the Mimas Real-Time Computer Vision Library to be able to compile and run depthoffocus-0.1 (652 kByte). The software also comes with sample files to generate photo-realistic 3D-reconstruction using POVRay!
Links
- Anaglyph images
- german diploma thesis about depth of focus (also available as PDF)
- Mechrob-paper Focus set based reconstruction of micro-objects
- Depth-from-focus applied in forensic science, MRT Karlsruhe
- Focus stitching software CombineZ5 and examples at http://www.micropics.org.uk/