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Camera/Video - PowerPoint Presentation

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Camera/Video - PPT Presentation

CCD DSP lux 36 mm f12 70 deg 13 Definitions radiometric vs photometric Photometry is just like radiometry except that everything is weighted by the spectral response of the eye Luminance ID: 303235

lens focal power lux focal lens lux power field length fov video camera sin view coverage light area ccd

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Slide1

Camera/VideoSlide2

CCD DSP

lux

3.6 mm f/1.2

70 deg.

1/3”Slide3

Definitions

radiometric vs. photometric

Photometry is just like radiometry except that everything is weighted by the spectral response of the eye

Luminance (

cd

/m2)-Describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle.

Luminous flux (lm)- The measure of the perceived power of light. It differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.

Lux (lx = lm/m2)-is the SI unit of

illuminance, and measuring luminous flux per unit area.QUANTITY RADIOMETRIC PHOTOMETRIC

QUANTITY

RADIOMETRICPHOTOMETRIC

powerwatt (W)lumen (lm)

power per unit area

W/m

2

lm/m

2

= lux (lx)

power per unit solid angle

W/sr

lm/sr = candela (cd)

power per area per solid angle

W/m

2

-sr

lm/m

2

-sr =

cd

/m

2

= nitSlide4

Illuminance

of surfaces illuminated by:

(Power/Area, Intensity)

0.0001 lux -Total starlight0.002 lux

-Moonless clear night sky0.01 lux - Quarter moon0.27 lux

-Full moon on a clear night1 lux - Full moon overhead at tropical latitudesSlide5

Focal length-f

The focal point of a lens is defined as that point at which rays from infinity (parallel rays) impinging on the lens are focused. The focal length is the distance of the focal point from the center of the lens.Slide6

F number

In optics, the f-number is given by

f

/D where f is the focal length, and D is the diameter of the entrance pupil

Ex. f =100 mm and D = 25 mm 100/25 = f/4 Ex. f= 200 mm and D = 50 mm

200/50 = f/4 The 200 mm lens's f/4 opening is larger than that of the 100 mm lens but both will produce the same

illuminance in the focal plane when imaging an object of a given luminance.Slide7

FOV (Field of View)

FOV underwater

Angle of coverage (FOV)

α = 2*tan

-1(d /2f)Note small f

large α

α

=80

° Field of View

α=8° Field of ViewSlide8

Snell’s Law

Diagonal coverage of lenses on the 35mm format

The refractive index of (sea) water was taken to be 1.339 for underwater (UW)

Focal

Length (mm)

Coverage

in Air (degrees)Coverage UW (Flat Port) degrees

1997.4268.27

2094.4966.51

2484.0660.00

2875.3854.34

3071.5951.80

α' = 2

sin

-1

[

Sin(

α/2) /

n

w

]

T

he port itself has no effect on the angle of coverage (although it does alter the effective position of the lens entrance pupil as seen from outside the housing

).

DerivationSlide9

CCD-Charged Coupled Device

Type

Aspect

Ratio

Diameter (mm)Diagonal(mm)Width (mm)

Height (mm)1/3.6”4:3

7.0565.004.00

3.001/3.2”4:3

7.9385.684.536

3.4161/3”4:3

8.4676.004.6

3.6

The type designation harks back to a set of standard sizes given to TV camera tubes in the 50's. These sizes were typically 1/2", 2/3" etc.Slide10

Depth of Field

Image distance vs. object distance

If the object becomes closer to the lens, the image moves further away from the lens and becomes larger.

If

one moves a real film plane back and forth a bit, a

range

of object distances remains in acceptable focus, this is the depth of field

One can

change the depth of field by changing the focal length or

aperture size of the lens. The width of the non-converged beam for the near-tree image becomes much less, and can be made too small to notice. Then both trees will be in acceptable focus.

Focus the camera on the far tree. Near tree out of focusSlide11

CCD-Charged Coupled Device

CCD Overview

Animation

DSP-digital signal processing

The signal processor within the camera receives the information from the charged coupled device, or CCD, and combines it into video framesSlide12

Some Calculations

Outland UWC-325/p

Focal length

f=3.6 mm f/1.2 Using

f/1.2=f/D and solving for DD= 3.6/1.2= 3 mmFOV α =

2tan-1(d / 2f)=2tan

-1(6/(2*3.6)) = 79.61oNotice that a

small f gives a larger FOVUnderwater FOV using nw

=1.339α' = 2sin-1[ sin(

α/2) / nw ]=2sin-1

[sin(80/2)/1.339]= 57.3 oSlide13

High-definition video

or

HD video

is any video system of higher resolution than standard-definition (SD) video, and most commonly involves display resolutions of 1,280×720 pixels (720p) or 1,920×1,080 pixels (1080i/1080p).

640 x 480 Pixels with 4:3 Aspect Ratio

1920 x 1080 Pixels with 16:9 Aspect RatioSlide14

Camera

Outland Technology

Seaview

Remote Ocean System

InsiteGoProGoPro 3D

Camera PottingOceanPro HD

Deepsea Power and LightLights-camera-actionSlide15

Glossary

f = F number

f

= focal lengthD = diameter of apatureα

= Field of View in air (FOV)α’ = Field of View in waterd = diagonal of imaging device