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 or a fan point in a building drawing.
Two points forms a line.
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. For example,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 most commonly used projections. These 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.||Here the object lies in the third quadrant.|
|When 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,||In this, front view is on the front,|
|Right side view is on left and so on.||right side view is on right and so on|