5_Recording of Energy by Sensor

8/19/2019 5_Recording of Energy by Sensor

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Recording of Energy by

the Sensor



SENSOR REMOTE SENSING IS

PERFORMED USINGAN INSTRUMENT,OFTEN REFERREDTO AS A SENSOR

THE SENSORREORD EMR !HIHTRA"E#S DIRET#$THROUGH THE"AUUM ORINDIRET#$ %$REF#ETION ORRERADIATION TOTHE SENSOR

HANGES IN THEAMOUNT AND

PROPERTIES OF EMRUPON DETETION %$

#EIA GEOS$STEMS AIR%ORNE DIGITA# SENS



Ty'es of Re(ote Sensing

M)ny sensors *sed in re(otesensing (e)s*re re+ected s*night-

So(e sensors, ho.e/er, detect

energy e(itted by the E)rth itsef or'ro/ide their o.n energy-



P)ssi/e Re(ote Sensing

The s*n0s energy iseither re+ected, )s it isfor /isibe.)/eengths, or

)bsorbed )nd then re1e(itted, )s it is forther() infr)red.)/eengths- Re(otesensing syste(s .hich

(e)s*re energy th)t isn)t*r)y )/)i)be )rec)ed ')ssi/e sensors)nd ty'e of RS is c)edP)ssi/e RS-



P)ssi/e Re(ote Sensing

P)ssi/e sensors c)n ony be*sed to detect energy .henthe n)t*r)y occ*rringenergy is )/)i)be- For )re+ected energy, this c)n

ony t)2e ')ce d*ring theti(e .hen the s*n isi*(in)ting the E)rth-There is no re+ected energy)/)i)be fro( the s*n )tnight- Energy th)t is

n)t*r)y e(itted 3s*ch )sther() infr)red4 c)n bedetected d)y or night, )song )s the )(o*nt ofenergy is )rge eno*gh tobe recorded-



Acti/e Re(ote Sensing

Active sensors,

on the otherhand, provide

their own

energy sourcefor illumination




The sensor e(itsr)di)tion .hich isdirected to.)rd thet)rget to be

in/estig)ted- Ther)di)tion re+ected fro(th)t t)rget is detected)nd (e)s*red by thesensor- Ad/)nt)ges for

)cti/e sensors inc*dethe )biity to obt)in(e)s*re(ents )nyti(e,reg)rdess of the ti(eof d)y or se)son-




Acti/e sensors c)n be*sed for e5)(ining.)/eengths th)t )re nots*6cienty 'ro/ided bythe s*n, s*ch )s

(icro.)/es, or to bettercontro the .)y ) t)rget isi*(in)ted- Ho.e/er,)cti/e syste(s re7*ire thegener)tion of ) f)iry

)rge )(o*nt of energy to)de7*)tey i*(in)tet)rgets- So(e e5)('es of)cti/e sensors )re ) )sersensor )nd ) synthetic)'ert*re r)d)r 3SAR4-



E5)('es

A c)(er) 'ro/ides )n e5ceent e5)('e ofboth ')ssi/e )nd )cti/e sensors- D*ring )bright s*nny d)y, eno*gh s*night isi*(in)ting the t)rgets )nd then re+ecting

to.)rd the c)(er) ens, th)t the c)(er)si('y records the r)di)tion 'ro/ided 3')ssi/e(ode4- On ) co*dy d)y or inside ) roo(,there is often not eno*gh s*night for thec)(er) to record the t)rgets )de7*)tey-Inste)d, it *ses its o.n energy so*rce 1 ) +)sh1 to i*(in)te the t)rgets )nd record ther)di)tion re+ected fro( the( 3)cti/e (ode4-



E5)('es

---R)d)r *sed by 'oice to(e)s*re the s'eed of tr)/eing/ehices is ) *se of )cti/e re(otesensing- The r)d)r de/ice is'ointed )t ) /ehice, '*ses ofr)di)tion )re e(itted, )nd the

re+ection of th)t r)di)tion fro(the /ehice is detected )ndti(ed- The s'eed of the /ehice isdeter(ined by c)c*)ting ti(ede)ys bet.een the re'e)tede(issions )nd rece'tion of the'*ses- This c)n be c)c*)ted/ery )cc*r)tey bec)*se thes'eed of the r)di)tion is (o/ing(*ch, (*ch f)ster th)n (ost/ehices---*ness yo*0re dri/ing )t

the s'eed of ight8



REMOTE SENSORS

Remote sensors: The detection and recording

instruments for RS

• Photographic cameras

• Mechanical scanners



SCANNER

Common Remote Sensing acquisition Technologies

(SCANNING)

– Frame Grabbers

– Whisk Broom (Across Track !scillating "irror

– #ush Broom (Along Track $inear arra% o&

'etectors



SCANNER – Frame Grabber



SENSORS USED TO O##ET DATA

THIS IS #I9EON"ENTIONA#AMERAS !ITHFI#M

ANA#OG FRAME AMERA AND FI#M



SENSORS USED TO O##ET IMAGES

DENSE ARRA$OF DETETORS#OATED ATTHE P#AE OFFI#MREORDINGENERG$E#ETRONIA## $

IGITA# FRAME AMERA AREA ARRA$



Scan Line

A horizontal row of pixels in an image forms a scan line

which is collected either

Sequentially as the sensor moves left to right whis!"room# or

Simultaneously through the use of a linear array of photo$

detectors frame gra""er% push "room#



Imaging Geometr%

– $ine Geometr%• #ush Broom (Along Track $inear arra% o&

'etectors ($ine sensors)

• Images a comlete scan line at an% one instanto& time

– #oint Geometr%• Whisk Broom (Across Track !scillating "irror

( #oint sensors)

•

Images onl% a single oint at an% one instant o&time



IN THIS THE SANNER ONSISTS OF #INEAR ARRA$ OFDETETORS 3D4

ONE1DIMENSIONA# ARRA$ OF Ds A#IGNED IN A DIRETIONPERPENDIU#AR TO THE F#IGHT DIRETION

EAH D AIMED AT A SPEIFI POINT ON THE GROUND !ITH THENEIGH%ORING D "IE!ING THE NEIGH%ORING GROUND#OATION:

ENTIRE #INE OF IMAGE DATA 3#INE OF PI;E#S4 A<UIREDSIMU#TANEOUS#$-

INEAR ARRA$ PUSH%ROOM : A#ONG TRA9 SANNE



o(bin)tion of ) singe detector )nd ) rot)ting(irror )rr)nged in s*ch ) .)y th)t the detectorbe)( s.ee's in ) str)ight ine o/er the E)rth)cross the tr)c2 of the s)teite )t e)ch rot)tionof the (irror- the E)rth=s s*rf)ce is sc)nnedsyste()tic)y 'i5e by 'i5e in e)ch ine )s the

s)teite (o/es for.)rd

#INEAR ARRA$ !HIS9%ROOM:ROSS TRA9 SANNE




IT IS #I9EPUSH%ROOMSANNER%UT THE

STORAGEOFENERG$ ISIN A

DIFFEREN

H$PER SPETRA# AREA:#INEAR ARRA$




THIS IS AN ATI"ES$STEM HA"INGO!N ENERG$SOURE AND DONOT DEPEND ON

SUN I##UMINATION

SIDE SANNING S$STEM




THIS T$PE OFSANNER HAS A"ERTIA# A;IS OFROTATION ANDON#$ THE

FOR!ARD PORTIONOF S!EEP ISREORDED TOPRODUE IMAGES

IRU#AR SANNER



Dwell Time

The length of time the &'() *sees* a ground resolution

cell as the rotating mirror scans

• +enerally quite short and influences the design of the

spatial% spectral% and radiometric resolution of the

sensor

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5_Recording of Energy by Sensor