Unit 2 Orthographic Projections
Unit 2 Orthographic Projections
one on
view HP horizontal orthographic
projections,
up three up 7.3 of of
7.1.
perpendicular in projections,required. mutual 7.2
and side Both the The In Perspective
Projections
anProjection
Oblique
In beINTRODUCTION
stationed taken
sameshapein 7.1
The PROJECTION PLANESOF the object. Axonometric Projections
(io) (in) (ii)
Orthographic
Projections () In (iv) (i) considered
(ü)
oronhorizontal
plane perpendicular the METHODS objectThe () Any
plan VP
lines of position vertical an
is the
other orthographic engineering The The The of
of on a For projection
at object an
by
commonly is profile of to threethree lines pointplane t he object
thcalled
eintersection t
position while
and both i.e. which the OF of particular
point
object. dimensional methods, of of has
plane
the perpendicular complete planes PROJECTIONS
drawing, sight
projection
vertical HP nis the
i projections, sight drawing fromdescribed is
Orthographic
Projections three
The
frontcallede e called
projection direction
ofin and eplanes or
dimensions
view these four planes, VP description
theprojections of towards
a
projection as the object four projection d
reference parts, is to objects
or three ,which vertical are an methods from
called the is object which
elevaionof ie.,
planescalled IVP,
usedtakenrepresented isare
or : the
on line profile
are plane for of length,
the is is
represented picture
the is th e
object
and are called the called gettingcalled represented projections of projectionis which
PP the called four plane (VP) three
is is as planes. into breadthis
object.
called horizontal or the as on the
gernerallydihedralprincipaly (PP). dimensional
a by a
coordinate frontal plane
different projection are pictureimage and
the The pictorial a Each by made. 7|
of two generally
angles plane, thicknesS. of
sidedenoted planes, planeplane
projection projection
views
view or
The the
axes. plane view object, more
view or (HP)- (FP). represents used following as object
quadrants byThe divide of by it In
or the The only. atleast than
appearsformed
online The e anor single which graphic
endletters
HP
isThe the third object.
second, picture In two are
viewthese two two are
viewintersectionofwhole as dimnensions views the language to by
called shown
Xy. plane, set Oneplane.In methods views as elements to rays
an
or space only. follows:
end the up is on observer of
in set inset- are the sight,
below
situated QUADRANTS
quadrants FOUR7.4 used by Cetc. #his
elevation
ORTHOGRAPHIC
PROJECTIONS
r
When elevation
small
the throughout Theirbook,
HP' in orthe letters actual of
any bytop the
anddihedral
planes
one withsmallviews
in points,
object.
'infront of this
Quadrant
BehindSecond
VP
AboveHP of double
letters or
the
angles, Quadrant3rd book. ends The
Quadrant
BehindVPThird
Below HP Angle Angle
Thlrd Second projections 2dQuadran plan
quadrants, of
dashes with
point
of
orwhich e
arlines,
Fig. Vertical
Plane
(VP)
behind dashesmarked of
its may are 7.1 Quadrant4h Quadrant-1 intersection
Corners
Fig. a",
relative
the extended Three b", a', by
7.2 VP. be c"
corresponding of
Fourth numbered planes etc. b',c solids
Four Angle Angle
First Vertical Plane (VP) position of
Profile
Plane
(PP) etc. the
beyond These
quadrants of The etc.
three
projectinns
Horizontal
Plane
(HP)
to as are side spacein
the the
shown coordinate
AboveHP
the small
Infront
VPofFirst planes line views
Below
Infront
VPof HP
CQuadrant
Fourth standard letters are
Reference
LIne Quadrant
in of denoted
or planes
being Fig.
intersection, Horizontal
Plane
(HP) end a,
7.2. conventions b,
described elevationcetc., by is
The capitalcalled
and
object they the
as frontviews
that are letters
denoted origin.
'above may form will
A, 81
four be B,In
or be
ofthe
the may between THIRD-ANGLE
PROJECTION
sightobtained
inbyis 7.6
ftof of
rightside view thereobserver FIRST-ANGLE
PROJECTION 7.5 followed,
sidelenoted
Similarly,
objectnormal thatbe pass In vlew
slde
Left the obtained PoStions respectively.
positions principal
through imaginedThe is 82
third-arngle InSimilarly,
and are In
object the first-angle; projection sA
nearer through the theof right two and by
object.the topits first-angle
away of
ofbecause 90°,
looking
object vieTopw sides planelooking ews
views viclockwise. to
to int it projection, Fig, object. side top
third-angle from tw o
it, viewand and and gat 7.3
view for view projof
an
projection, projection.
ectiaton, overlap. donot only eitherbesaidsaisi
as observer
then the Presentation Thus,
it, and the
shOwn Thus VP as mayobject first to
in sidereach object an overlapHowever, in be
shown in be side object an That and
third-angle
projection, verobjectis
. first-angle obtained
a (left view
first the
Fig.
in view fromobject is third
the The from in left side
of Fig, side a re rig ht is quadrant,
why thesein onlplyanes first
74 areobject.planeimagined right orthographic and
projectionobtained a projection
7.3. view for obtained
imagisidened secondquadrants two are angle,
left any right
ofside Front
view HP
quadrants. systems madesecondsecond
side projection PP object.
is side),ofquadrant. to and are
of to obtained by ENGINEERIDRAWINGNG AND
ary view byquadrant. be views ary be fourth always ie., lito e angle,
looking positioned so
looking quadrant, the in
view is view two positioned Wher eas
obtained imagined is in on
first angle opened first one third
is at In viewTop Front
view
isthÁ pOssible at thisIn
so
so the this in angle the in
in aplnd ane thirdangle
placed object, third placedproBle object, case, firstprojections second
by case,
to projection vieWs
out tbeihinrod by
or
placing
that quadrant.
bet the the le
whilangle
holquadrant
ding fourt h
thatplane from normal quadrant. and
it
transparent it
object are rotating
fourth COMPUTER
rthe plane o45°45o anglore
represents by the notprojectionsare VP
itsto view
side
Left placing side itsto wil The used. the and fourth
ofThe
Tepresentsprofile
i.e.
surfae front
in
be quadrants, rotating when
planes.
surface. projandectionfront quadrantGRAPHICS the
theplane rays of vie the it left between view
to
side the s cbject
side to If is is the The Hp
ORTHOGRAPHIC
No
S.
5. 4 3. 2 1 Table
6
Countries
Commonly Used objectOctant
Position ofPlane Position ofQuadrant 7.1
Common
point
of Difference
Let / PROJECTIONS
viewsprojection Fig. slde
7.4 view
between
Presentation
European
countries.
and thelevatlon.
e This right ofthe lies In be The and The The The viewzside
Left
Bureau non-transparent.
above
xy this plane planeobjectobject object
method andmethod, First-angle
projection
method
first-angle
PP
left the of oflies lies lies of
of 451
Indiars is side xy, front projection
projection. in in inorthographic VP vlewTop
commonly top between the the projection
viewelevation
view view or first first
Shandards is or is theoctant.quadrant.
used drawn plan assumed observer method views Frontview viewTop
(BIS) by to
belowelevation in
the to third-angle
and
USA This view or transparent In beto
between
The The third The
The quadrant.
plan this plane planeobject object Third
third-angle Front
view
and
method is HP
drawnabovemethod, the projection
other lies of lies isangle
object of in
is tobelow projection assumed projection method
countries. projection the projection
commonly the thexy and
left thefront seventh
ofand xy, the to
is liemethod
elevatlon. left top view assumed observer. lies
used octant. in
83
side view or in the
in
7.7
plane7.6 surface 7.3
t 7.5 7.4projection,
In.........27.1
7.4 7.3
The What In 7.27.1 84
orthographicIn of A Front These done
method is 7.7
view(iv) Write Why Fig.
Front
view
Drawthird and
three Explain
() orthographic What For
is the Principalthird-angle 7.5 by
PROJECTION
METHOD
symbols everySYMBOLS
short the Symbol
planes plane a angle
symbols do shownmeans
an projections with you
projection, notes are drawing,
of
of object planes the mean
projection for adopted.
of it
in a
projection
projection
projection for projection
on help first-angle
actuallysymbolic USED
FOR
Fig.
sraeppas the of by shown
.7.5,
first-angle vieTopw (v) () an of is
cejbotis
the orthographic side
view
Left
the neat of obtained absolutely
igure for
e.
arlines ..iS method
OBJECTIVE Reference object an projection while
?inQUESTIONS sketches, Fig.
itpositiorned
s are
object?
projection
of true 7.7
FIRST-ANGLE
from thatdrawn
line not projection.? EXERCISES method essential
sight positioned Frustum the for on
shape, drawn the the a
are method in difference projections title to
.....
...ss
and
between Projection
view
Side(ui) (iii) of EERINGNGAND
when Fig.
third-angle blindicate
ock. ENGINDRAWI
in
in Describe a PROJECTION
and second cone 7.6
to between
it the between of The the
third-angle
the is Symbol view
side
Left
... observer and briefly frustum
projectionsymbol
plane the method
fourth
first-angle for
observer the third-angle ofdrawn METHOD
of thep t.o
projection and aod of
ection. the quadrants? method cone
methprojection
andplane projection as AND COMPUTER
projection
method shown s is
first-angle
projection. 1
object.
of of
method. obtaining Front
view THIRD-ANGLE
projection.of
method in in
Fig.
projection GRAPHICs
Fig. This
the 7.7.
7.6.
is
ORTHOGRAPHIC
PROJECTIONS
7.11 7.10 7.9 7.8
First-angle
Perpendicular
7.9 7.6 7.1
HP Distinguish What
What Following
’Horizontal
is is
a the
profile symbol
between full
name
plane, 7.7 7.2 planerepresents
Horizontal,Plane the of
and HP'
VP’ terms
of state
projection and first
Vertical Projector
vertical, its VP? or
ANSWERS use? third
plane and angle
profile
Projection'
projection.
planes
by
Parallel
Third-angle
projection
7.8 7.4 means
of
suitable
sketches.
85