CIVIL ENGINEERING DRAWING & GRAPHICS CH (1+2) Lecture 4: Elements of perspective drawing Dr. Mohsin Siddique Asst. Prof. Dept. of Civil Engineering FAST-NU 12/09/2012
ISOMETRIC AND PERSPECTIVE VIEWS BASICS • Isometric or perspective views are of great importance to architect, draftsman, town planners and engineers as these help them in conveying their perceived objects to the laymen and unskilled workers before construction of the project. • Types of three dimensional views ▫ (1). Isometric Projection ▫ (2). Axonometric Projection ▫ (3). Oblique Projection ▫ (4). Perspective Projection
ISOMETRIC AND PERSPECTIVE VIEWS BASICS • Isometric views: It is drawn by imagining the objects principal three edges making equal angles with the plane of projection. • Axonometric view: It is drawn to show the upper part in more details. The objects principal edges are imagined to be making 60o on one side and 30o on other side with the horizontal plane. • Oblique view: When one side of object is to be shown clearly, this view is used. The front object is kept parallel to the plane of projections and one edge is inclined at 30o-45o to the horizontal. • Perspective view: It shows an object in its true shape as it appears to the eye.
PERSPECTIVE PROJECTIONS BASICS
PERSPECTIVE PROJECTIONS • Perspective view or projection gives the appearance of an object as it appears to the human eye. • It is similar to photographic picture. • In a perspective projection all the projectors appear to meet at a point e.g., if an observed stand in the railway track, the railway lines appear to meet at a point. • If such a view is drawn with the help of drawing instrument on a plane, it is know as perspective projection.
PERSPECTIVE PROJECTIONS
PERSPECTIVE PROJECTIONS
PERSPECTIVE PROJECTIONS TECHNICAL TERMS • Picture Plane: The imaginary vertical plane between the observer and the object on which the perspective is obtained is know as picture plane. It is abbreviated as PP • Ground Line: The line of intersection of ground plane and vertical or picture plane is called ground line and it is denoted by GL. • Center of vision: The point where the line of vision pierce the picture plane is centre of vision. • Horizon: Horizontal line drawn through center of vision on the picture plane.
PERSPECTIVE PROJECTIONS TECHNICAL TERMS
• Station Point: It is the point of sight where all projector converge • Vanishing Point: It is a point on the picture plane where all the parallel lines appear to converge.
PERSPECTIVE PROJECTIONS TECHNICAL TERMS • Angle of vision: Draw the plan of the object. Join the station point with two extreme corners of the object. These two extreme corner lines enclose the Arc of Vision. The angle formed between these lines is known as angle of vision.
PERSPECTIVE PROJECTIONS TECHNICAL TERMS • Measuring line: The intersection of the plan of the object with picture plane gives the true height at the point of intersection, when measured in elevation. So any side of the object which lies in picture plane shows the true height of the object. • Eye level: It is a line at the eye-level of the observer and is represented by straight line. Its true height is observed from ground line.
CLASSIFICATION OR PERSPECTIVE • Shadow Perspective or Pictorials and • Linear Perspective ▫ One-point perspective ▫ Two Point perspective ▫ Three point perspective
ONE POINT PERSPECTIVE • When all set of parallel lines appear to converge at a single point of convergence, the perspective is called one point perspective. • The set of horizontal and vertical lines of the object which are in the picture plane or parallel to it shows their true height and width in the front. • The depth lines converge towards a common vanishing point
ONE POINT PERSPECTIVE
Can you locate the Horizon Line? How did you determine this? Can you find the vanishing point in this picture?
ONE POINONE POINT PERSPECTIVET
The red line is the Horizon Line.
ONE POINT PERSPECTIVE Can you locate the vanishing point?
TWO POINT PERSPECTIVE • Face of the object is kept inclined to the picture plane while drawing it. • There are two vanishing points: one on the left and other on the right side. • This perspective is used for buildings and other engineering assemblies. • It shows more than one face of building and thus makes this type of perspective more illustrative.
TWO POINT PERSPECTIVE
Locate Vanishing Point
TWO POINT PERSPECTIVE Objects seen at an angle would be drawn with two-point perspective using two vanishing points.
THREE POINT PERSPECTIVE • In this perspective, all the three sets of parallel lines converge at three different vanishing points. • This is mainly used for drawing perspective of very tall building or towers, since the vertical set of parallel line also appear to converge at a vanishing point.
REFERENCES
• A course in Civil Engineering Drawing • By V.B Sikka • Google search engine
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