camaras fotogrametricas (2) - copia

8/6/2019 camaras fotogrametricas (2) - copia

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Analog Aerial Cameras

SensorsZ/I DMC

Leica ADS40Comparison

2.6 * H104 (116 gon)88 mmSuperwide

1.5 * H73 (82 gon)152 mmWide angle

1.1 * H57 (63 gon)210 mmNormal angle

0.8 * H41 (46 gon)300 mmNormal angle

0.4 * H22 (24 gon)600 mmNarrow angle

Ground coverageOpening anglecLens type

Main manufacturers are Wild and Leica.All use film size 230x230 mm.

Jonas Nelson

AnalogAerialCameras

SensorsZ/I DMCLeica ADS40Comparison

It is not just onelens, but a set ofabout 10-12 lensesthat make up theaerial camera lenssystem.


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AnalogAerialCameras

SensorsZ/I DMC


Actually, a camerahas TWO perspectivecenters, one at the

front of the cameraand one at the rear.

Jonas Nelson

Image Info



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Sensor Types CCD pushbroom

For colour images they use one for Red,one for Green and one for Blue.= three-line scanner.

SensorsZ/I DMC


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Sensor Types CCD array

2D CCD arrays can be black/whiteor use filters to capture colour.



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All sensors are black/white

Each light-sensitivepixel is identical, imagesensors record onlythe gray scale.Basically, they onlycapture brightness.

In order to get colour,you have to addcoloured filters infront of the sensors.These filters will ofcourse steal some ofthe transmitted light.

On the Fuji SuperCCD there are small lensesconcentrating the light before passingthrough the filters and reaching the pixels.

SensorsZ/I DMC


Jonas Nelson

CCD array designs

A typical CCD imagesensor has squarephotosites arrangedin rows and columns.

The Super CCD fromFuji uses octagonalpixels arranged in ahoneycomb pattern.



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CMOS chip properties

CMOS image quality is now matching CCD quality in thelow- and mid-range, leaving only the high-end image sensorsstill unchallenged.

CMOS image sensors can incorporate other circuits onthe same chip, eliminating the many separate chipsrequired for a CCD.Not only does this make the camera smaller, lighter, andcheaper; it also requires less power so batteries lastlonger.

CMOS sensors have a higher noise level than CCDs so theprocessing time between pictures is higher as thesesensors use digital signal processing (DSP) to reduce oreliminate the noise.

SensorsZ/I DMC


Jonas Nelson

CMOS chip properties

CMOS sensors suffer in low light conditions. Theirsensitivity to light is decreased because part of eachphotosite is covered with circuitry that filters out noiseand performs other functions.

The percentage of a pixel devoted to collecting light iscalled the pixels fill factor.

CCDs have a 100% fill factor but CMOS cameras havemuch less. The lower the fill factor, the less sensitivethe sensor is and the longer exposure times must be.



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Comparison: CCD - CMOS

- Mass-production like IC.- Cheap (1/3 of the CCD).- Integrated with circuitsdoing signal processing.

- Requires more light.- Slower due to more noise.

- Special production lines.- Expensive.- Separate chips for processing.- Requires more power.- Higher quality than CMOS.

Both CCD and CMOS imagesensors capture light on a gridof small pixels on theirsurfaces.

It's how they process the imageand how they are manufacturedwhere they differ from oneanother.

CCD CMOSSensorsZ/I DMC


Jonas Nelson

Camera Design Options

One Array

Black and White

Colour Bayer Matrix

Three-layer chip - Foveon

Multi Array

1 lens + multi-chip

Multi-lens with 1 chip each



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Bayer Mosaic Pattern

There are twice as many green filters as there arered or blue filters. That's because a human eye ismore sensitive to green than it is to the other twocolors so green's color accuracy is more important.

SensorsZ/I DMC


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Bayer Mosaic Interpolation

"I'm bright green and the red and bluepixels around me are also bright so thatmust mean I'm really awhitepixel."



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Foveon three-layer CMOS

Similar to a colour film, the Foveon three-layer CMOS has semi-transparent layerssensitive to different colours.

SensorsZ/I DMC


Jonas Nelson



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Multiple Chip Design

Beam Splitter

SensorsZ/I DMC


Jonas Nelson

Airborne Digital Sensors

Z/I DMC Leica ADS40

Applanix DSS

Vexcel UltraCam D



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Z/I DMC

SensorsZ/I DMC


4 panchromatic CCD arrayseach 7000 x 4000 pixels,Final image 13824 x 7680

4 multispectral (R,G,B, NIR)CCD arrays,each 3000 x 2000 pixels

Pixel size: 12 m x 12 m

Field of view (FoV) or swathangle: 69.3across strip,

42along strip

Focal length: 120 mm (pan)25 mm (MS)

Stereo angle: 42

Jonas Nelson

Z/I DMC - cameras

4 panchromatic high-resolution (7000x4000) CCD cameraheads, covering a quarter each. Focal length 120 mm.

4 multispectral (R, G, B, Near IR) CCD camera headswith 3000x2000 pixel resolution each. Focal length 25 mm.



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Z/I DMC panchromatic cameras

To speed up reading of the sensors, each sensor has itsdata downloaded from all four corners.Still takes 2.1 seconds / image.

12x12 micrometer pixel size.

Radiometric resolution is 12 bit (4096 levels).

SensorsZ/I DMC


Jonas Nelson

Z/I DMC camera placement



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Z/I DMC camera placement

SensorsZ/I DMC


Jonas Nelson

Z/I DMC - footprint

7680 pixel

13824pixel



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Z/I DMC the virtual image

SensorsZ/I DMC


Jonas Nelson

Z/I DMC the virtual image



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Z/I DMC mosaic

Left: Virtual image center after:

- tie point extraction & matching- lens corrections- rectification

A perfect geometric match!

Right: Virtual image centerafter applying radiometriccorrection / blending of thefour images.

The final product is a verygood mosaic!

SensorsZ/I DMC


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Global radiometric correction

Standard radiometric correction(changing the grey values throughhistogram equalization).



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Local radiometric correction

Defect column (no data; black) in the sensor isradiometrically corrected through interpolationtechniques.

SensorsZ/I DMC


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Local radiometric correction

Defect area in the sensor (darker) is

radiometrically corrected automatically since it issystematic (you always know which pixels andhow much to correct them).



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Z/I DMC stereo model

Two consecutive virtual images (left + right) workas a normal stereo model. However, the B/Hratio is lower due to sensor size.

SensorsZ/I DMC


Jonas Nelson

Leica ADS40

3 panchromatic CCD lineseach 2 x 12,000 pixels,staggered by 3.25 m

4 multispectral CCD lines,each 12,000 pixels

Pixel size: 6.5 m x 6.5 m

Field of view (FoV) or swathangle: 64(across strip)

Focal length: 62.77 mm

Stereo angles: 16, 26, 42

Sensor head SH40



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Leica ADS40 system

GPS satellites

GPS ground reference station

ADS40 system

1

2

34 5

6

1 Sensor head SH40 with:

- Digital optics DO64- IMU

2 Control unit CU40 with:- position & attitudecomputer POS

3 Mass Memory MM40

4 Operator interface OI40

5 Guidance Indicator GI40

6 Mount PAV30

SensorsZ/I DMC


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Leica ADS40 - sensors

3 panchromatic 12000 pixel line scanners (forward, nadir, back)

4 RGB+NIR 12000 pixel line scanners



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Leica ADS40 - panchromatic

3 panchromatic line scanners = three seamless image strips.

Forward 26 , nadir 0 and backward 16 .

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Leica ADS40 pan level 0 and 1

The output (raw data, level 0) from an airborne line scanner hasa jumbled appearance; the ground footprints are not parallel,owing to the movement of the aircraft. This is rectified using datafrom GPS and IMU.



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Leica ADS40 multispectral

Ideal bands for remote sensing applications should be narrowand non-overlapping, whereas the requirement for high qualitytrue-colour images dictates broad, overlapping bands.

SensorsZ/I DMC


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Leica ADS40 RGB beam splitter

A tri-chroid beam splitterensures that the incomingRGB light from the samearea of the ground isregistered in all three RGBarrays.

This means perfect RGBco-registration and betterresolution for each colour,compared to sensors withBayer pattern.



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Leica ADS40 radiometric correction

SensorsZ/I DMC


Jonas Nelson

Multispectral comparison


Ideal bands for remote sensing applications should be narrow

and non-overlapping, whereas the requirement for high quality

true-colour images dictates broad, overlapping bands.

Pan (no info) 465-680 nmBlue 400-580 nm 430-490 nmGreen 500-650 nm 535-585 nmRed 590-675 nm 610-660 nmNear IR 675-850 or 740-850 nm 835-885 nm

DMC ADS40


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Airborne / Spaceborne comparison

SensorsZ/I DMC


Jonas Nelson

DPWS System Manufacturers

1E1440Lecture 1

PhotogrammetryZ/I, Leica, ESPA, Geosystems, Inpho

Remote SensingI2S, ERDAS, PCI, ERMapper, TNTmips,Vexcel

Digital CartographyDAT/EM, ISM

MilitaryHelava, Intergraph, Automatrics

UniversityDMS, DVP, VirtuoZo...

HistoryTerminologyDigital ImagesResolutionManufacturersComponents


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DPWS in the center

1E1440Lecture 1

HistoryTerminology

Digital ImagesResolutionManufacturersComponents

Vector data

Satelliteimages

RadarimagesScanned

aerial images

CCD,Video Laser

scanner

Existingmap data

ExistingDEM Digital

PhotogrammetricWorkStation

GISWorkStation

Classedsatellitescenes

Raster data

Attributes,

tables

Triangulation,orientation data

DEMContoursProfiles Ortophoto

Digitalmap data

CAD, AutoCAD

Operator

Jonas Nelson

Leaving the hardware

1E1440Lecture 1


The early stages (1988-1996) saw a lot ofintegrated hardware+software stand-alonesolutions (dedicated hardware).

Now, the computer development have made

the photogrammetric companies focus onsoftware, often on multiple platforms(Unix/Windows).

But the software is expensive since it is sospecialised and sold in few copies.


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Buy it all - or transform your PC

1E1440Lecture 1

Z/I Image Station- Dual 21" monitors

- Dual Pentium Processors

- Win 2000

- 3Dlabs Wildcat graphics card

-Emitter

- CrystalEyes

- 3D Mouse Hardware cost:

About 10 000 USD

Z/I Stereo Softcopy Kit- Emitter

- CrystalEyes

- Graphics card

- 3D mouse (Immersions 3D softmouse) Hardware cost: About 3000 USD

HistoryTerminology


Jonas Nelson

System Components

1E1440Lecture 1


Central Processing Unit (CPU). Should be fast!

Operative System (OS). 32-bit real-time processing.

Main Memory (RAM). 256 Mb is a minimum.

Storage. Hard disc of several Gb. Slower mass storage.

Graphics Display System. Graphics card and monitor(s).

3D Viewing System. Stereo viewing in colour if possible.

3D Measuring Device. See User Interface below.

User Interface. GUI, keyboard, mouse, trackball, handwheels.

Network. Scanner, printer, GIS, internet.


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Memory Components

1E1440Lecture 1

HistoryTerminology


Monitor, 4 Mb+ (1/60)

Graphic card, 16 Mb+ (1/15 image)

RAM, 256 Mb+ (1 image)

Hard disc, 20 Gb+ (86 images)

Peripheral mass storage, 100 Gb+ (425 images)

(23x23 cm aerial image, 8-bit b/w with 15 m pixel size)

Jonas Nelson

3D Viewing

1E1440Lecture 1


The human brain requiresseparation of stereoimagesin order to get a 3D view.

Separation method Practical implementation

Spatial 2 monitors + stereoscope1 monitor (split screen) + stereoscope2 monitors + passive polarisation

Spectral AnaglyphicPassive polarisation

Sequential Alternated synchronised display,active polarisation or LCD


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3D Viewing pros and cons

1E1440Lecture 1

HistoryTerminology


Implementation Advantage / Disadvantage

2 monitors - Bulky- Only one observer

Split screen - 50% Field of Vision+ stereoscope - Only one observer

Anaglyphic - No colour images + Several observers- Bad transmission + Very cheap

Passive - 50% resolution + Several observerspolarisation - High initial cost + Cheap glasses

LCD and Active - 50% resolution + Several observerspolarisation - Expensive glasses

- Flickering

Jonas Nelson

Polarisation screen + glasses

1E1440Lecture 1



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Split-screen + stereoscope

1E1440Lecture 1

HistoryTerminology


GeoSystem

Delta DPS from GeoSystem (Ukraine)(Also available with 3D glasses)

Note the hand- and footwheels!

Jonas Nelson

Monitor requirements

1E1440Lecture 1


24 bit monitor for viewing colour images.

120 Hz for good refresh rate withsequential stereo viewing.

1-2 million pixels required (minimum). 1280x1024.

The resolution may determine the accuracy. One (large) or two monitors. 21+

More than two images can be shownsimultaneously.

Overlays of graphic (map data) in 2D or 3D.


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3D measuring devices

1E1440Lecture 1

HistoryTerminology


Mouse

Mouse + trackball

Hand- and footwheels

(from analytical instruments)

Rat (device from analytical instrument)

camaras fotogrametricas (2) - copia

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