PROJECTION OF POINTS-Short Question Answers

PROJECTION OF POINTS- Short Question Answers

Projection of a point is used to show the location of a light, fan point in a building drawing.

Line projection is the projections of its two ends.


Q. Describe the position of points in the various quadrants and its projections

with respect to the reference line xy.


Quadrant  Position Position of front view  Position of top view
1st In front of VP and above HP Above xy Below xy
2nd Above HP and behind VP Above xy Above xy
3rd Behind VP and below HP Below xy Above xy
4th Below HP and in front of VP Below xy Below xy


Q. Discuss some key features about the projection of points.


(i) Distance of the front view is always from the HP.

(ii) Top view distance is always from the VP.

  • If distance is above HP, front view is above xy and vice versa.
  • If point is in front of VP, top view is below xy and vice versa.

Q.How are the projections of a point marked for its front view and top view?


(i) Front view is marked by a small alphabet with a dash. The front view of point H will be h’.

(ii) Top view is marked by a small alphabet without a dash. The front view of point H will be h.

  • Point as such is written by a capital alphabet.

Q. Which are the types of projections mostly used in engineering drawing?


Orthographic projections are done on HP, VP and PP planes. Since projections are done on a plane,

these projections are 2 dimensional.

Q. What are the different methods of projections in use?


First and third angle projections are in common use.

First Angle Projection Third Angle Projection
Object lies in the first quadrant. Object lies in the third quadrant.
Object is in between the observer and the vertical plane. Vertical plane is in between the observer and the object.
Front view is on the back, Front view is on the front,
Right side view is on left and so on. right side view is on right and so on