Projection of Point
Point may be defined as a circle having infinitesimal radius. A dot of pencil is an example of point.
Projection of point in first angle
In first angle of projection the
point is placed above the HP and in front of VP.
The distance in front of the VP = b
p’ = front view
p = top view
In angle of projection, horizontal
plane is always rotate clockwise direction and the intersection of HP and VP is
called reference line represent by XY. Draw reference line on a paper, above
portion of XY line is VP and below portion is called HP shown in figure 2.
The distance above the HP is shown
on vertical plane (VP), and the distance from VP is shown on horizontal plane
(HP). Figure 2 shows the orthographic projection of the point in first angle of
projection.
Figure 1: - Point in first angle of projection
Draw the reference line XY
Draw point p’ above the XY at a
distance ‘a’ above the HP
Draw projection from p’,
perpendicular to XY and mark point p at a distance ‘b’ in top view as shown in
figure 2.
Figure 2: - Projection of point in first angle of projection
Projection of point in Second angle
In this angle of projection point is placed behind VP and above HP shown in figure 3.
Same as first angle of projection,
horizontal plane is always rotate clockwise direction and the intersection of
HP and VP is called reference line represent by XY. Draw reference line on a
paper, above portion of XY line represents both HP and VP because of overlapping
of HP and VP. The front and top view of the point is lies above the XY line
Figure 3: - Point in Second angle of projection
Draw XY line
Draw front view of the point at a
distance of ‘a’ above the XY
Draw projection from front view
perpendicular to XY
Mark a point p at a distance of ‘b’
from XY give the location of top view of the point shown in figure 4.
Figure 4: - Projection of point in second angle of projection
Projection of point in Third angle
Draw reference line on a paper, above portion of XY line represents HP and below portion of XY is VP shown in figure 5.
Figure 5: - Point in third angle of projection
Draw XY line
Mark a point p above the XY line at
a distance of ‘b’ called top view of the point
Draw the projection form p
perpendicular to XY line
Mark a point p’ at a distance of
‘a’ below the XY called front view of point shown in figure 6.
Figure 6: - Projection of point in third angle of projection
Projection of point in Fourth angle
Draw reference line on a paper, below portion of XY line represents both HP and VP because of overlapping of HP and VP. The front and top view of the point is lies below the XY line shown in figure 7.
Figure 7: - Point in fourth angle of projection
Draw XY line
Draw front view of the point at a
distance of ‘a’ below the XY
Draw projection from front view
perpendicular to XY
Mark a point p at a distance of ‘b’
from XY give the location of top view of the point shown in figure 8.
Figure 8: - Projection of point in fourth angle of projection
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