CE2O24-REMOTE SENSING TECHMQUES & GIS
I]NIT-5 2-marks
l.
Deline DEM? The term digital elevation model or a
EDM is frequently used to refer to any digital representation of
topography surface, however, most o{ien it is used to refer specifically or a raster or regular grid
;.DEM's" raster file containing elevations at regularly spaced surface coordinates ofspot heights. In
.
over an area is interpreted using specialised computer software, which creates a 3D rendering ofthe surface.
2.
What are the uses of DEM?
i) Determining atkibutes terrain, such as el€vation
at any point, slope and aspect'
ii)Finding features on the terrain, such as drainage basins and watersheds' Drainage networks and ohannels, peaks and pits and other landforms'
iii) 3. Wiat
Modelling ofhydrologic functions, energy flux and forest fires'
is meant by spatial analysis?
entities ln statistics, spatial analysis or spatial statistics includes any ofthe techniques which study using their-topological, geometric or geographic properties.
4.
/ oac-Qolo) is the pr*ei bt *hi"h it i$*mle
What is overlayingz Map overlay
of the other and form map ovorlay is
{xte
a
v
to take two or more different thematic map layers
composite new tayer this technique is used to overlay vector based system
tine cons.rning complex and computationally expensive. In raster
base systems it is
quick, straightforward and efficient.
5.
-
What is buffering? 9\',,/
{ No") De L'-fuotl)
to detemine The creation of a zone oi interest around an entity. It is an important function used map features. spatial proximity or neamess of various features by defining a distance zone around Buffer can be generated for points' lines and polygons'
6.
What is reclassification?
ofthe query idea in GIS and is used in place ofa query in raster GIS' In undel raster GIS, the method ofreclassification can be in place ofquery to obtain information
it
is an important variation
search from a GIS database.
7,
What are the different input method into a GIS? The dif.ferent methods of input into a GIS are by,
i) iD iii)
Keyboard Manual digitizing Scanning and automatic digitizing
P.RamamoorthyAsst'Prof/Civil
Page 1
8.
What are the advantages and disadvantages ofraster.and yector? Advantages:
Raster model
Vector model
/ Simple data structure r' Easy and efficient overlaying / Individual identity ofdiscrete objects like line, / Compatible with remote sensing imagery polygon, etc. r' High spatial variability is efficiently represented r' E{Iicient projection transformation / Efficient to represent continuous data y' Accurate map output
Derine roporogy?
4:yJl:::i9?1)
A branch of geomeui.rilu,t,.rn.rt..
*ffi
concerned with order, contiguity and relative position rather than actuar linear dimensions. The descriprion ofrow spatial features are connected
each other-
,0.
(
lvov)
oac - e ::n1":':,*trutu It is defined as observation, measurem"nt
b\)
,od r-fl""tion of information abour the actuar conditions on the ground in order to determine the relationship between remote se"ri.g _O ,h" ;
";;
observed-
ni.f-tunoneebqlupao g ?c 7i oJ 4 ata- r a 4.oys
;"
lpalroJ onA rao- sre-l'i d ).ala-). &yJ:*'=)
ba d ic a,vaq) ry {e al un'p-, ^ le.l tuyA) o ac.pip) a Lt Cotliah, > i"isi;';'/q eo,!^ io) ao s2eci*c localiaq ,h g.2"oQ-'Jt coq lorn d./\o/y '- A av.a q t)a k-e-4 /o o- geagta/4 f C- Locaittzn 9@ gT4-?4 i c- a.mfuq-eq ^nA hz 5 fgL*t *3-"4 nbutz, *AalA arq aon- s2tr./';64 bc.l caq ba liq l
>
lo
9oo
P.Ramamoorthy,Asst.prof/Civil Page 2
-ia 1::-
ll.
Detine TIN? Triangular Irregular
Nefiork
is a digital data structure used in GIS for the representation
ofa
structure. A series
triargles are
of triangles constructed using elevation data poins takea from coverage,s. These used for surface representation and display.
r^
plna/-\LIs? ( B
12. what is meant bv
4o
b)
Land Information system means to acquire, manage, retrieve, analyse, display
flexible land surface modelling and data assimilation frame rvork develo@
hd
*ith
records. LIS is
the goal
a
of
integrating satellite and ground based observationai eiata products and adnanoed hnd sgrface
modelling techniques to produce optimal fields of land surface states and
fures.
13. What are the difference between Raster and Veclor form?
Raster: Data in pixel, grid format, capturing
analysis and retrieving data-
Vector: Data in point, line andpolygon format, 14. Define Land use and
srores spatiai and non spatiat
&ils
Land cover?
Land use: Low the land is utilized by natural and various manmade acrivifi= lfte agrinlnre, plant3lion. buildings. etc.
Land cover: Natural cover of earth surfaces like oceani agricuturre and desert
hilB
e*c.
ls.What are the types of GIS data?
. .
Athibute Data Spatial Data.
16,What are the types of spatial data models?
.
Raster
Vector
.
lmage.
l7.Whal are the major data sources of GIS?
o . . . o .
.
Conventional analog map sources Report
& Publications
Aerial Remote Sensing Satellite Remole Sensing
Field data sources (or) Surveying
& Global Positional
System.
Exisiing digital map sources.
P.Ramamoorthy,Asst.Prof/Civil
ttE"3
F,
i
4r,
nN
lFy sl^n)s 4,/ 2,
Attr- Dqlomalo4 rnLTh^J .: rN - {o i I i Lia4 rn ar\a',gen,,\1o+ . 18.What is meant by intersect? An intersect overlay definer
the area where both inputs overlay
for each-
& retains
a set ofattribute fiejd
l9.What are the types ofvector overlay?
. . .
point_in-polygon.
t
Line_on_polygon. polygon_on-polygon-
20. What is meant by network analysis? Network anarysis is a range oftechniques
emproyee engineer and pranners to study the properties
networks, including connectivity, capacity and rates
2I. What is meant by Reclassificatio Rectassification is ro reassign
n.*
rt
in a new merged data set;hat is data to create a new layer.
of
offlow.
oZ Qvo r/ pn a - goatl )
"ruri"ii;;;
fa, within
sparial features which resuks
a crass according to crassification scheme are merged
(e.9.) Districr map ofindia. all districrc ara.a.^^:^,^r accordins to their
c,"..,"..,;3',:J"::'":'"
;Iiffi.of
#;T :H:;*
.atus. we can merge rhe dishicts
22. Define is GpS?
! I
r
Globar Position Sysrem is a space based saterite navigation system that provides location and time where on or near the *rth, *r,"." th.." is an unobstructed line of iight
:?JHj:'#"::Tanv QJ, u,hol;s rneoil
b1 a/cr|Lulo, -@y/r*u_g"tq) allr bu-las a4.a +te oJonooJ.r)slii- -74i6J 4e"luney 9 lotding o/ lAt &2c;p7ive- jn qtr,nal;aa -,bc,u-l *As- gea g /aal,*as , p./lvi/t', ,r'o s "cll\l;( aoo *Az Dbo- gPal;a! 4oli o+so u'afu2 .- ill, t;cnp- g a+ea- ealg;a2 .r,1,ul
T;;::;X.:,4*::x,1";:;,3,:"y:":#;i'.?-,ff ft tt
kz .tM I
a"vdsn
'
g
0iSJiqgui^SL bala
li
*lo!
)ala )
;r,:ti il"t ,i' . gp* Snt /ocalfiry nud ic;l I ilo! nolu*ol''
P,Ramamoorthy,Asst. prof/Civil Page 4
z, al+Sxneot usio$ nenota Seosiog
tlu. inVrastztcture' rnadenn d-LLou,
,9oce i
thi
t7
t/zcz-(
.
Pd-sgeDfldl
Pd4, 'prx'tt4,vtt ,9/zoLz/e/
ba leq-sl a
) ro . czvoicled cti tico_/ *orie /'tpA. G,)ecE k Sotl oYeaS, ,.eYoS c oD _ pv-one zoDe tr- n c,/ * t ood PTot) o. c44 oes .
:
i
i> *teour w)t
ll
a.ligning iS a
c^ois;urne
te
d.ioug
[email protected]
ano/ tl
t;r$A tpsc'tA Jesg aca ,,laleLl
,-71a ?.e.
Arts recent/y loeao 9o/veo/ ;ef(ecttuatT ',.>
usz"ng
&rs 81 lzorv)ote Sentioq tee/t nt7ueS
rhe qu{o rn
i
:zn thia ccnlexy' tc
P
'
p"'aeegs using &t9, /ennt"nq U
sical' envi {cnD)e .-ntat , pol; liont, soczal , e co1orn tcct-l enc/ lega.t pravsSI .. €tc a.ncl trmple,ne,rLeel *o, "r-iloay routt'tX :
:
:eleterrnina/iotl :
.
.
bz
ce'nstcl a.'r P LY
a
'.t
,I
the {t"rsd sut fu r'rtu
/qla
cL(Lt@.
be4e u-;ihl
Neu; rail
4.
&t,9
:.'
CilzJL;oy'oh, :
otg i [cil Elevay'lon xqade!. ad
rai/ eottiday. cuitA
.
,:
atha,l &ts uset
/rag<
*o
:l
?t
,v)a-ps
pyep
crZ
ec/
bo.t
J
inl>u/ ta the 6ts 4at6
I
c; zv e31
baSe.
"t-s-zr:lS,
e
:'trw,zi naX
decz 1t.,yes,
v*itrrry s . elevatiob poio ts
_
l?aat
p
tqre
ye ol.eriveel
.
:
..,) oilterenl ;alap ictec,L
' z
.
oleotnoyp
frr"" Un/ I
ma'Xe b?/
in
Jancy'gartas
d;g;tit
to lAe &rs dczta
ettyaclec{ grorr, the a{e-la f nterpretatioo ano/ ineo tp€ Te
be-se.
l
.>
&eornayplie
aoe..ts
P/afeant,
utere ctassi 7fc.ed ioto
Bcrap EooeDeby.,., .9Jopa bcz
zaclq,
/Zasid_4o,1
f,;11
?aM_Y
t
1> /'eeali ott
.E v:\/ey , ,:lretioag€ co/?a,
Foc.,rl-h. €t gth ovcl e >' <,f, ,gtteatrss J ez't
thgd,
dzaina.Te peite r r) I
t^
-!'
bt
Bra;dg ag
slale
thczt
lo
t? cresslns %
<27
,-; ni nJ a)lea ,
Sec<,o
Iroru-:
tL,G.l a /
3
cot'tS /-n
ttearttS ,
pyep
tral
Tn4az
tztS
necaS3.cc^'X
'
e:necl Srom
ri er-tlt u ra / ^/*t rcl
,
Sq.le
11;ta
pIao ta 11tt':s, b bo<,kt .,r ',
anreo zccr,
_qq.lt,.ty .tl.)ap s- +-
> n a.ps pzopo4p7J ustnS
ToposLee(
> io tdeoti fa 7y,s typas.
c6
stq-
ntdeta,(e
ITa
iJ*,I.'*.,
._fiDpe)
tt -
- -:
i
6lcpe s,
/"/DqJP
SoveslS,
urbaD .r/ee..g.
-::!f-g,
f,
la-rap g
> Land t.e,se rneps a)e-.5
r*.
ve.",/
. t petrt)t
nclI
> Zl ist o-dvi
aDd
ftr-91,
(cor) (deep slry- gt*tc
i-u!
) parlrose d
th;s
lu<
conStc:lev tra71rc, p;t
e"nso.rrrt@, > Lls
fuAh
kz
lf c,n, t\gk
8{ee,
t"rOl,
b*tegtts eo,qtiilfe b tAL
.n a thoct,
nttnt rnun>
-/. b Z-57- . rlze cD*t iS eo,-Pu,y'zd a,* cueijhted Su,n oS Jard a?acc;sttr:bl) eoz t" tz-ta{e rtczy' cn-l*, ex.ca.c,cz/ian
to
cat
L a:oap*anslaP
eo4t'
'
?a9! -tD
.1
t'
Explain on the different methods of Data lnput in GlS.(Nov/Dec-2O10) Data lnput Methods Before explaining the input methods, it is necessary ro make a distinction between anarogue (nondigital) and digitar sources of spatiar data. Anarogue data are normary in paper form and incrude paper
meps' iables converted
of statistics and hardcopy aerial photographs. All these forms of data need to be
to digitar form before use in a GIS. Digitar data rike remote sensing data are arready in compute-readabre formats and are suppried on diskette, magnetic tape or cD-RoM or across a computer network A, data in anarogue form need to be converted to digitar form before they can be input into'Grs There are four methods of data input
which are widery used: keyboard entry, manuar digitising, automatic digitisation, and scanning. Digital data must be downloaded from lheir source media and may require reformafting to convert them to an appropriate format for the Grs being used. Reformatting or conversion may arso be required aftef anarogue data have been converted to digitar form' For exampre' after scanning a paper rflap, the fire produced by the scanning equipment . may not be compatibre with the Grs, so it needs reformatting. For both the anarogue and digitar data, keyboard entry method, manuar digitising and automatic digitizing and scanning methods are very impo(ant as
detailed below.
Keyboard Entry Keyboard entry, often referred to as keycoding, is the entry data into a fire at a computer terminar. This 'technique is used for attribute data that are available only on paper. This technique can be mixed with digitising process for the creation of Gls database as discussed in chapter 13 for the land use/and cover database for Hyderabad city. The aftribute data, 'once in digital format, are linked to the relevant map features in the spalial database using identification codes. There are unique codes that are a'llocated to each< point, line and area feature in the dataset. The coordinates of spatial entities like
point, line and area features can be encoded by keyboard entry. This method is used when the coordinates of these spatial entities are known and there are not too many of them. lf the coordinates are more in number, this data can be encoded using digitising. The procedure of keyboard
entry can be used to enter land record information. This method leads to obtain very high level of precision data by entering the actual surveying measurements. This method is used for the development of cadastral informatioh system.
Manual Digitising Manual digitising is the most common method of encoding spatiar features from paper rnaps- n b a process of converting the spatial features on a map into a digital format. point, line, and area Edres P.Ramamoorthy,Asst prof/Civil
&!!rt
;,g,i'*ist
t-
that form a map, are converted into (x, y) coordinates. A point is represented by a single coordinatei a
line by a string of coordinates, and, when one or more lines are combined with a label point inside an outline, then an area (polygon) is identified. Thus digitising is lhe process of capturing a series of points and lines. Points are used for two different purposes: to represent point features or to
identify the presence of a polygon. Manual digitising requires a table digitiser that iJ linked to a computer work station (Fig 10.2). To achieve good results, the following steps are necessary. Before,
discussing these steps, the description
of digltisers is provided for the beginners in this field
of
technology. Digitisers are the most common device for extracting spatial information from maps and photographs. The position of an indicator as it is moved over the surface of the. digitizlng tablet is detected by the computer and interpreted as pairs ofx, y coordinates. The indicator may be a pen-like 'stylus or a cursor. Frequently, there aic conirol buttons on the cursor which permit control of ihe system without having to turn attention from the digitising tablet to a computer terminal. The current most popular digitiser is contdmporary tablets using a gird of wires embedded in the tabldl to a generate magnetic field which is detected by the cursor. The accura'cy of such tabtes are typically better than 0.1 mm which is better than the accuracy with which the average operator can position the
cursor. Sometimes the functions for transforming coordinates are built into the tablet and used to process data before it is sent to the host (Fig 10.2).
Fb-
iO2 Coluryorsi raar.i' lrl.lr a t r d ri!3 sEDedd.d h Are tanlct to gener.E r maSnetis lbrd $+idr a ,.*itd ty |tr qrr.
P.Ramamoorthy,Asst.Prof/Civil
Page lP
'rtol<:
"f ft,e
-l
r
Btsltts{ng
OpGr'a,'{ten
s,*;ilrtffi,3{,n"Eg$"}*ffi
polots Er6 calkd r€f€ rsnct
n"
*
HT""fr}?ff,TJl"--"
::ntror-pqiniE ,"n
$fl*#,J:j?,r^=ix.#tff
*'*,
*5''g5*:;irytlifr*#*=*rli."r$ilt
r+mnmt=ffi$#,um:p#rTm3ffi rjH{i# F.roblefia ,iyi.th trlgifi*i,.lq
tH aps Tho trrpblerris that o(rl rnode through i;; ;;[Ji* furins.lhe Proaess or converting lhe maps tnto diortat oepends upon ths ***r,*n"-t- oPitlssrlon val'v from one c*o ip"oror-iJ ,riltiJrl' , , ano polygons of the mao- ,ff^11o skill o_f l}le @eralor.and d€nsity of proints, tines accu r acY o{ the outout t pon
trre
u
i.erectL;
piooremsJulL,;';i;'i,fi ";l'j,'.ir'J" ,H?j,;:;'"'ff
ffi:rg#;f
"
ut"
abiuiiit; ;i';;';;#;=
H,","?,,Jf
;''l;t""HTJL
tri (:i)
fiBqff Fr::E,,ilrffie:flEJ,[rHffi S,ffi;ifl 1f4t"#t,e;H,i3 fiffi J5t[tri#"lf H,:,,'L?I#JIll_3".3TH;=,1".#L"J3$11J_1H
{[ii] Errors occlu r c.n ltlese rrt.sr an{, Js, these €n'drs g,rq entere{, f.nto t.re mse 9s $reil. Gls d€ta ti"] tire Gis dar€iba.sa, is rlirecw r,e..tarec ff_HilJt;:Hjn to tha error rever of
tv)
Hi"1".,1T?lB;liT"r
infsi,rnarton_ and d$ nor always EccuferBry record
q*.,n:xf '*Um*"*'.r*q*:#:T:{",fl""#fi
Fig. 1O.3 Map3
!nr,='"'il'#"#HTn:
"*m
P.Ramamoorthy,Asst prof/Civil
rte
.',
rs
F. F
E.
F
F,5. 1r;16
.*--"-.o.r-E
P.Ramamoorthy,Asst
profEivii Page
I
\
"f*ruy r-b.",L veotw O
anA
vufuo Aa4ao-'oda]-4)
ta
ii,
i
l-.j,
i.,
tran$fbrmed to a s.oquence of raster
l r
P.Ramamoorthy,Asst.
prof/Civil Page
/6
\
O eo?n ^ *boal JaTf q co''nfuoztr'tq
O
h;ejLy oy?ta,a
+l,j_
*silitel;6()
pyDcesseg )n Cotg t
Dlgitizart on: You supply an urban or regi,
",.,n"p"i",ron
2-
;;*?r:TfJn:l:,";Tffi.;sv'
(.y/,,^n
e6)e)
sas and waler o. vou operare
Present is on paper. Becausr
system,i.,,t".al;;;;;:".".",,,*ia*;::ffi.fl a tormat suitabte ,or your GtS systen].
J,iliH*1T,L".;:
h the digital files all-cables, pipes, cjimensions, oparational ' .on lhe technically obiects etc. must be ptac€d approp ate layer All cables pipa,,n"", captlred and digjtized geo ret "*"r" and objects mug be
isonhundreds;,.;;;;T;T:::,::1ffi
shortest time and in high quality-
P.Ramarnoorthy,Asst. prof/Civil
;flT;fl ,!lli"J;:i,f
**
ilP rF
>
DtiEae,&are t
>
rna* a,o phobgr+tu. Tlp nry, ptnao, o ofircr docrrmrr arErr
e,qd qmrdl devica fur q'afi.
iabre{-
ic pbEsd b irr*.r
_ .._ - - srrfueLdcEq[HrE ol lre 3
mapisaffi
map shept
o
theiertri[ be peaks.
P.
pdrB
c€+hu me.Q
Tcsf, eb_) are digitized for each
prtfthefu
dmaiorst
€et3, najor
Ramamoorthy,tust.prof/Civil Page
t{
to celculate fhe oec
hf done in tvro different fiodes:
t F
o
r
slream mod@ris mote demandjrg on the user wh.ile point mode reguire$ some Judgments about how lo represent the line
6ns€ smof most:map$ wore not drafted fA!lhe purpose of digilizing paper rnaps are unstable: each time the map is removgd fiom the digitizing table, the refere.nce points must be re_entered when the map is affixed lo the table again
o
t F
.
o
if the map has stretched or shrunk in the interim, the newly digitized points wilt be slightJy off in their location when compared to previously digilized points
Plamarnoorthy,Asstprof/Civil
frge
.-
;;;-
r9
].'
o
enors occur on these maps, and hese errofs are enlered
F. E. f:
i
mAps ai6 meant to display informalion, and do not always
locational information
placed next to each other
1984
Editing erlors from digitizing:
.
so l0
o o I
.
corrected autqnatically srnall gaps at line junctions o\Ershoots and sudden spikes in lines
error rates dryend on the carnprexity of the rnap, are high for complex mad
srna
scale,
hese topics are explfred in greater deliail in later Units o Unlt 13 looks ai the process d ediling dtgitized data
o
P.Rama
errDrs can be
Units 45 and 46 discuss dgilizinJ enor
moorthy,Asst.Prof/Civil
Page
lo
irr.
+! i*uu a,b:eg.*3;ff[U]tr3r';"'" . @nigl,ris,,l ggjf-a"n'' ('*'i ' '*.^ Jetnd {armo.i.ioo
scara
rn Land information system (LIS)
Means to acquire, manage, retrieve, analyse, display land records.
. . '
component of GIS or vice-versa... a long-standing debate, mostly a matter of semantics and disciplinary orientation. Typical LIS: LIS as
o
maintained by unit of government responsible for tracking land ownership, control; typically county government in US parcel-oriented hard copy maps and/or CAD or GIS software for spatial representations relatively large (cartographic) scale (e.g., 1:4800 in rural areas, 1:1200 in developed areas)' bridge between legal (e.g., deeds) and technical (e.g., maps, GIS coordinates) land descriptions may incorporate other technologies parcel indexing systems (relational data base. management systems) fiche and document imaging systems surveying multipurpose cadastre National Research Council effort of early 1980s -.--o--recognized limitations in manual systems proposed automated methods for managing land records, linking to other spatial data parcel as primary organizing principle
o o o o o
.
.
. .
o
o
. .
o
multipurpose land information svstem o alternative to multipurpose cadastre o parcels as one component of layer-based system o oriented to integration and analysis of data o geodetic reference framework as organizing principle
Land Tgnure.
.
Rights and obligations in land, along with system for defining and governing.
Difficult to capture all tenure rights in
a land
information system -- multiple
dimensions.
P.Ramamoorthy/sstProf/Civil
fie
41
r t
.
i i
definition of rights o "bundle of sticks,, _ all the possible ways of using Iand, allocated betweenl individuars (and organizationsl *," ,ir-t'""10r other form of society) o rules and procedures defining who "na porr"rr*,Jrf,,.f, sticks _ can be MORE EXpLtCIT and MORE COMplEif *i,f, ,ri"r"iua frna informationi system o responsibilities _ obligations oftenure Oorr".ror, e.g., land taxation, environmental protection
Land records components of regal and fiscar cadastre maintained by locar governments (typicary counties)
Many components amenable to automation; appropriate data models still evolving . titles - a description of a.l.and parcel, potentially including: o description of location. or b.#.ry i;.;.;;arings and distances survey description, metes.and Uorna, aer.ripiion',"prUf i. land survey system reference, lot number i" plrtt"d;;il;ir,.r, o method of conv ",..f
_ _.,ro*ens,
','..,Tll{i; Ji,';#iiT,lill::*::#:fr
;",,:,1",,, governmen-t backs claim to land title resistration or r.na t'.nsuJi;ffih pubric authority (Register of
' 3::::i
I
h N
o
I
.
i
.
J;x":ff
i:
,
:[:,:?1:[:
",
l:., :::il," registration is esl;entially voluntary though typically done to support claim to land o grantor and gra ntee.(conveyed from, to) used to organize records (manuat system _-> ,bo"k, *t;;; r.rJ,, ,, ,."r""."f chains of title _ a fully supported land claim ;;r;; traced back to original conveyance from goveinment or.ro*n, through all tr€nsactions to present is "rr""." ira.,r, chain ortitte; ;;;;;; i,rrnrnrri.ation of chain of indexes - to make chains of title easier to research. f cr.eategrontor/g**""i,n.an,"rr;;;;;;;;;;;,';:::5:Hrrrr#,f
o
.
land transaction are hprr^,o-^ ;^.J;..:r._-, o n,y re q u re J ; ."J;:y :
i
,
;ff:io,* P. Ra
and tinked to Grs represen;;;,;;;;';"[h
spatiaily into parcer
mamoorthy,Asrt-p;rm Page AQ
jt,
tax roles, tax maps -- other than Registry (which is maintained as public service) the main interest of local government in land ownership information is tax assessment. Tax roles and associated tax maps: accoult for all lands, their value and their owner. may or may not be directly linked to Registry may or may not be derived from deed/title descriptions often used as source of data for GIS (Registry typically not involved in
o o o o
mapping) . o often not maintained at accuracy needed to convey land, onty to assess and collect taxes related "layers" -- assessment, zoning, permits, etc. private records o title insurance -.private backing of title validity o title abstracts - summarization of evidence about ownership o plat maps -- approximations of land ownership parceis, derived from a variety of public and private data sources
P.Ramamoorthy,Asst.Prof/Civil
GilE
2,
