Measurements in Fluid Mechanics058:180 (ME:5180)

Time & Location: 2:30P - 3:20P MWF 3315 SC

Office Hours: 4:00P – 5:00P MWF 223B-5 HL

Instructor: Lichuan Guilichuan-gui@uiowa.edu

Phone: 319-384-0594 (Lab), 319-400-5985 (Cell) http://lcgui.net

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Lecture 38. Stereo high-speed imaging

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Stereo High-speed Imaging

Gray value resolution

10-bit CMOS sensor

17.5µm pixels

Frame rate & digital resolution

10241024 @ 2000 fps

1024256 @ 8000 fps

- High-speed camera

Stereo High-speed Imaging- Optical configuration outside the

camera Mirror

Lens

Mirror

Alate

Mirrorimage

Mirror image

Front view

Side view

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Stereo High-speed Imaging

Lens adaptor

Mirrors

Image sensor (1024256)

Block

Slit apertures

Lens

Mirror images

- Optical configuration inside the camera

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Stereo High-speed Imaging

High-speed camera Mirrors Back lighting

Tethered fire ant alate Microphones

- Experimental setup with sound recording

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Stereo High-speed Imaging- Experimental setup with sound recording

Sound recorded from bottom & rear with MCDL

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Stereo High-speed Imaging- Sample image & postprocessing

Raw image

Background

Processed

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Stereo High-speed Imaging

70 frames in the period of 8.8 ms (114Hz), bar chart represents sound pressure

- Synchronize motion w. sound in one period

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Stereo High-speed Imaging

- New optic table and magnetic holders for higher precision - New template for adjusting mirror angles to ensure 90o difference between front and side- views

- Tested ant body carefully oriented

- Improved system for wing motion reconstruction

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Stereo High-speed Imaging

O: root of the wing T: tip of the wing 3: the 3rd point at the wing surface

- Position & orientation of the wing • the wing assumed to be a planar surface without thickness

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Stereo High-speed Imaging- Wing root position

More frames may be necessary for higher accuracy & reliability

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Stereo High-speed Imaging- 3D view of the wing surface

: angle between wing surface & plane through OT & OZ

xy: wing angle in xy-plane

zy: wing angle in yz-plane

Angles

Pink: wing surface

Yellow: OT & OZ

Planes

Axis of the wing: OT

Axis of ant body: OZ

Axis's

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Stereo High-speed Imaging

Wing surface function:

BzAxy

333 BzAxy

BzAxy ttt

B

A

zy

xy

1

1

tan

tan

OT&OZ surface function:

Cxy tt xyC /

Wing rotation angle:

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1cos

2221

CBA

CA

- Data reduction equations

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Stereo High-speed Imaging- Example I: BIFA male test on July 8, 2006

Image size: 590190 pixels, digital resolution: 22.35 pixel/mm

Body weight: 5.5 mg Body length: 6 mm

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Stereo High-speed Imaging

t/T [T=9.25 ms]

Win

gtip

posi

tion

[mm

]

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

xt

yt

zt

Forwing

t/T [T=9.25 ms]

Win

gtip

posi

tion

[mm

]

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

xt

yt

zt

Hindwing

- Wing tip position of the BIFA male

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Stereo High-speed Imaging

t/T [T=9.25 ms]

Win

gsu

rfac

ean

gles

[]

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-120.0

-90.0

-60.0

-30.0

0.0

30.0

60.0

90.0

120.0

xy

zy

Hindwing

t/T [T=9.25 ms]

Win

gsu

rfac

ean

gles

[]

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-120.0

-90.0

-60.0

-30.0

0.0

30.0

60.0

90.0

120.0

xy

zy

Forewing

- Wing angles of the BIFA male

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Stereo High-speed Imaging- High resolution picture of the forewing

O T

Image size: 850×300 pixels Digital resolution: 128 pixel/mm

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Stereo High-speed Imaging- High resolution picture of the hindwing

O T

LH

Gray value distribution: G(L,H)

Image size: 850×300 pixels Digital resolution: 128 pixel/mm

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Stereo High-speed Imaging- Simulating images form three view angles

(x,y,z)H

L

gf(x,y)=G(L,H)

Front view image:

gs(z,y)=G(L,H)

Side view image:

gt(x,z)=G(L,H)

Top view image:

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Stereo High-speed Imaging- Original (top) and simulated (bottom) images

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Stereo High-speed Imaging- Reconstructed 3D view of the male

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Stereo High-speed Imaging- Overlapped image of 74 frames

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Stereo High-speed Imaging

– Reference•  Gui L, Fink T, Cao Z, Sun D, Seiner JM and Streett DA (2010) Fire ant alate

wingmotion data and numerical reconstruction. Journal of Insect Science 10:9,available online: http://insectscience.org/10.19