Perspective - ENGINEERING DRAWING AND PLANS- Perpective Notes PDF

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ENGINEERING DRAWING AND PLANS- Perpective Notes...

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PERSPECTIVE

The word “perspective” means the proper relative position of objects as seen. Perspective drawing is the only drawing which represents contemplated building as it would appear to a spectator. It is the representation of an object on a plane surface as it would appear to the eye when viewed from a fixed point. It is the representation of an object on a plane surface as it would appear to the eye when viewed from a fixed point. Perspective, in the vision and visual perception, is the way that objects appear to the eye based on their spatial attributes or their dimensions and the position from the eye with relative to their each other. The importance of perspective:    

Add a logic factor, to the elements and objects in design. Add a depth with different dimensions, the design work. Keeping the true proportions and measuring of the elements and subjects, in the different dimensions of the design. Perspective triggers movement in the viewer’s eye, engaging them and drawing them into the work.

Types of Perspective  Linear Perspective As objects become more distant they appear smaller because their visual angle decreases. The visual angle of an object is the angle subtended at the eye by a triangle with the object at its base. The greater the distance of the object from the eye, the greater is the height of this triangle, and the less the visual angle. This follows simply from Euclidean geometry.

The basic terms and definitions that is inherent to linear perspective drawings. 

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The horizon is the line for which the sky meets the land or water below. The height of the horizon will affect the placement of the vanishing point(s) as well as the scene’s eye level. The vanishing point is the place where parallel lines appear to come together in the distance. In the picture, below, you can see how the parallel lines of the road recede and visually merge to create a single vanishing point on the horizon. A scene can have a limitless number of vanishing points. The ground plane is the horizontal surface below the horizon. It could be land or water. In the image below, the ground plane is level. If it were sloped or hilly, the vanishing point–created by the path’s parallel lines–may not rest on the horizon and may appear as if it’s on an inclined plane. The orthogonal lines are lines which are directed to a vanishing point; the parallel lines of railroad tracks, for example. The word “orthogonal” actually means right angle. It refers to right angles formed by lines such as the corner of a cube shown in perspective. The vantage point, not to be confused with the vanishing point, is the place from which a scene is viewed. The vantage point is affected by the placement of the horizon and the vanishing points.

Two basic rules of linear perspective: Rule #1: Objects that are closer appear bigger.

Rule #2: Parallel lines intersect at the horizon.

 Aerial Perspective Aerial perspective refers to the effect on the appearance of an ordinary object (not a self-luminous object) of being viewed through the atmosphere. In daylight, as an ordinary object gets farther from the eye, its contrast with the background is reduced, its color saturation is reduced and its color becomes bluer. Aerial perspective or (atmospheric perspective), refers to the effect the atmosphere has on the appearance of an object as it is viewed in different distances. It means when the distance between an object and a viewer increases, the contrast between the object and its background decreases, and the contrast of any markings or details within the object also decreases. The colors of the object also become less saturated and shift towards the background color, which is usually blue, but under some conditions may be some other color (for example, at sunrise or sunset distant colors may shift towards red). Atmospheric perspective occurs because particles in the air, such as water vapor and smog, affect what is seen. Forms viewed from a distance are not as defined and have less contrast because there are more particles in the atmosphere between the forms and the viewer. Likewise, the wavelengths of color are affected by distance. Blues bounce around, whereas the longer color wavelengths are not affected by particles in the same way. The result is that the blues remain more visible than the other colors in the spectrum.

The values are the lights and darks of a composition. Intrinsic to atmospheric perspective, values can influence the impression of depth in a scene. Highly contrasting values tend to appear forward of values with little contrast. The lighting of a scene affects shadows and values of forms. It can also affect how those forms are perceived.

Five Levels of Linear Perspective  One Point Perspective One point perspective is a type of linear perspective and it is in the same level of viewer’s eyes. It relies on (withdraw the lines of all shapes in the vision, towards one point only), to render the objects in the depth of space, and form in a flat work of art. It is a structured approach to drawing. One point perspective gets its name from the fact that it utilizes a single vanishing point.

Steps in drawing a one-point perspective drawing: 

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Draw the given plan on the extreme top of the drawing sheet. Note: If the station point is to the left of the plan, draw the plan on the extreme top right and vice versa. Mark the picture plane and the station point on the plan with the help of the given data. Draw the given elevation at the bottom of the drawing sheet. Note: If the station point is to the left of the plan, draw the elevation on the bottom left and vice versa. Leave adequate distance between the station point and the elevation for a neat drawing. Draw the ground level and mark the vanishing point on the elevation with the help of the given data. Draw the true shape of the face lying on the picture plane with the help of projections from the plan and elevation. Note: Straight faces only will maintain their true shapes in the perspective; inclined faces will not maintain their true shapes in the perspective. In the plan, join points of details (wall edges, windows, doors etc) of the face NOT lying on the picture plane to the station point. In the elevation, join the points of details of the same face to the vanishing point. Note: No projections from the true shape face can be directly joined to the vanishing point. Projections must be first transferred to the edge of the tapering face and then joined to the vanishing point. Similarly, inclined edges on the true faces are also to be first projected on to the edge of the tapering end and then joined to the vanishing point. To get the details of the tapering end in perspective, draw projections of the same from the lines joining the station point at the point where they’re cutting the picture plane. Join the details on the tapering face to complete the one point perspective drawing....