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## Calculating velocities

Now we would like to calculate the velocities from the images. We use the window shifting technique mentioned above and start off with large images and end with after 6 iterations. The images are taken with a time separation of s and we will use overlap of the interrogation regions.

>> [x,y,u,v,snr,pkh]=matpiv('mpim1b.bmp','mpim1c.bmp',...
[64 64;64 64;32 32;32 32;16 16;16 16],...

* Pass No: 1
No. of vectors: 1094 , Seconds taken: 19.606562.
Global filter running - with limit: 3 *std [U V] ..... 2 vectors changed
Local median filter running: ...........................
............2 vectors changed.
Interpolating outliers: ....4 Nan's interpolated.
Expanding velocity-field for next pass
Interpolating outliers: .1 Nan's interpolated.
* Pass No: 2
No. of vectors: 1094 , Seconds taken: 20.628889.
Global filter running - with limit: 3 *std [U V] ..... 0 vectors changed
Local median filter running: ...........................
............3 vectors changed.
Interpolating outliers: ...3 Nan's interpolated.
Expanding velocity-field for next pass
Interpolating outliers: ................218 Nan's interpolated.
* Pass No: 3
No. of vectors: 4402 , Seconds taken: 17.721477.
Global filter running - with limit: 3 *std [U V] ..... 1 vectors changed
Local median filter running: ...........................
...............................................
.....3 vectors changed.
Interpolating outliers: ....4 Nan's interpolated.
Expanding velocity-field for next pass
Interpolating outliers: .1 Nan's interpolated.
* Pass No: 4
No. of vectors: 4402 , Seconds taken: 17.555643.
Global filter running - with limit: 3 *std [U V] ..... 0 vectors changed
Local median filter running: ...........................
...............................................
.....1 vectors changed.
Interpolating outliers: .1 Nan's interpolated.
Expanding velocity-field for next pass
Interpolating outliers: ...............................460 Nan's interpolated.
* Pass No: 5
No. of vectors: 17673 , Seconds taken: 26.574317.
Global filter running - with limit: 3 *std [U V] ..... 24 vectors changed
Local median filter running: ............................
..............................................
..........................................................
...........................257 vectors changed
.
Interpolating outliers: .................................
................281 Nan's interpolated.
* Final Pass
- Using 16*16 interrogation windows!
No. of vectors: 17673, Seconds taken: 33.649626
* Calculating the pixel to world transformation using linear mapping - DONE


Johan K. Sveen 2004-08-06