Projection of points Lect 5.ppt
- 1. G. B. PANT DSEU OHKLA-III CAMPUS BASIC ENGINEERING GRAPHICS WEEK 5 SESSION 1 INTRODUCTIONS TO PROJECTIONS 1
- 2. INTRODUCTION • 3D Objects can be represented in number of different ways, depending on the purpose such as for artistic or technical, on a 2D paper/plain. • The thickness of paper in 3D is useless and computer screen is also a 2D representation. Therefore, a lot of efforts made to address the problem of trying to represent 3D images in 2D. • Various projection methods were evolved to solve this problem.
- 3. Projection of Points Horizontal Plane (HP), Vertical Frontal Plane (VP) Side Or Profile Plane (PP) Different Reference planes are FV is a view projected on VP. TV is a view projected on HP. SV is a view projected on PP. And Different Views are Front View (FV), Top View (TV) and Side View (SV)
- 4. A.V.P. to Hp & to Vp PLANES PRINCIPAL PLANES HP AND VP AUXILIARY PLANES Auxiliary Vertical Plane (A.V.P.) Profile Plane ( P.P.) Auxiliary Inclined Plane (A.I.P.)
- 5. THIS IS A PICTORIAL SET-UP OF ALL THREE PLANES. ARROW DIRECTION IS A NORMAL WAY OF OBSERVING THE OBJECT. BUT IN THIS DIRECTION ONLY VPAND A VIEW ON IT (FV) CAN BE SEEN. THE OTHER PLANES AND VIEWS ON THOSE CAN NOT BE SEEN. HP IS ROTATED DOWNWARD 900 AND BROUGHT IN THE PLANE OF VP. PP IS ROTATED IN RIGHT SIDE 900 AND BROUGHT IN THE PLANE OF VP. X Y X Y VP HP PP FV ACTUAL PATTERN OF PLANES & VIEWS OF ORTHOGRAPHIC PROJECTIONS DRAWN IN FIRST ANGLE METHOD OF PROJECTIONS LSV TV PROCEDURE TO SOLVE ABOVE PROBLEM:- TO MAKE THOSE PLANES ALSO VISIBLE FROM THE ARROW DIRECTION, A) HP IS ROTATED 900 DOUNWARD B) PP, 900 IN RIGHT SIDE DIRECTION. THIS WAY BOTH PLANES ARE BROUGHT IN THE SAME PLANE CONTAINING VP. PATTERN OF PLANES & VIEWS (First Angle Method) Click to view Animation On clicking the button if a warning comes please click YES to continue, this program is safe for your pc.
- 6. NOTATIONS FOLLOWING NOTATIONS SHOULD BE FOLLOWED WHILE NAMEING DIFFERENT VIEWS IN ORTHOGRAPHIC PROJECTIONS. IT’S FRONT VIEW a’ a’ b’ SAME SYSTEM OF NOTATIONS SHOULD BE FOLLOWED INCASE NUMBERS, LIKE 1, 2, 3 – ARE USED. OBJECT POINT A LINE AB IT’S TOP VIEW a a b IT’S SIDE VIEW a” a” b”
- 7. X Y 1ST Quad. 2nd Quad. 3rd Quad. 4th Quad. X Y VP HP Observer THIS QUADRANT PATTERN, IF OBSERVED ALONG X-Y LINE ( IN RED ARROW DIRECTION) WILL EXACTLY APPEAR AS SHOWN ON RIGHT SIDE AND HENCE, IT IS FURTHER USED TO UNDERSTAND ILLUSTRATION PROPERLLY.
- 8. HP VP a’ a A POINT A IN 1ST QUADRANT OBSERVER VP HP POINT A IN 2ND QUADRANT OBSERVER a’ a A OBSERVER a a’ POINT A IN 3RD QUADRANT HP VP A OBSERVER a a’ POINT A IN 4TH QUADRANT HP VP A Point A is Placed In First quadrants and it’s FV & TV are brought in same plane for Observer to see clearly. FV is visible as it is a view on VP. But as TV is is a view on HP, it is rotated downward 900, In clockwise direction. Thus HP comes below xy line and the Point on VP comes above. Observe and note the process.
- 9. BASIC TERMS FOR DRAWING PROJECTION OF POINT FV & TV of a point always lie in the same vertical line FV of a point ‘P’ is represented by p’. It shows position of the point with respect to HP. •If the point lies above HP, p’ lies above the XY line. •If the point lies in the HP, p’ lies on the XY line. •If the point lies below the HP, p’ lies below the XY line. TV of a point ‘P’ is represented by p. It shows position of the point with respect to VP. •If the point lies in front of VP, p lies below the XY line. •If the point lies in the VP, p lies on the XY line. •If the point lies behind the VP, p lies below the XY line.
- 10. A a a’ A a a’ A a a’ X Y X Y X Y For Tv For Tv For Tv POINT A ABOVE HP & INFRONT OF VP POINT A IN HP & INFRONT OF VP POINT A ABOVE HP & IN VP PROJECTIONS OF A POINT IN FIRST QUADRANT. PICTORIAL PRESENTATION PICTORIAL PRESENTATION ORTHOGRAPHIC PRESENTATIONS OF ALL ABOVE CASES. X Y a a’ VP HP X Y a’ VP HP a X Y a VP HP a’ Fv above xy, Tv below xy. Fv above xy, Tv on xy. Fv on xy, Tv below xy.
- 11. Exercise Q1. DRAW THE PROJECTIONS OF THE FOLLOWING POINTS ON THE SAME GROUND LINE, KEEPING THE PROJECTORS 25 MM APART: • A, IN THE HP AND 20 MM BEHIND THE VP. • B, 40 MM ABOVE HP AND 25 MM IN FRONT OF THE VP. • C, IN THE VP AND 40 MM ABOVE THE HP. • D, 25 MM BELOW THE HP AND 25 MM BEHIND THE VP. • E, 15 MM ABOVE THE HP AND 50 MM BEHIND THE VP. • F, 40 MM BELOW THE HP AND 50 MM BEHIND THE VP. • G, IN BOTH HP AND VP. Q2. A POINT P IS 50 MM FROM BOTH THE REFERENCE PLANES. DRAW ITS PROJECTION IN ALL POSSIBLE POSITIONS.