Lesson 6
PICTORIAL DRAWING
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LESSON 6 OUTLINE
LESSON 6 OUTLINE
Lesson 6UNDERSTANDING OF PICTORIAL DRAWING
UNDERSTANDING OF PICTORIAL DRAWING
STEP BY STEP GUIDE - PICTORIAL DRAWINF OF STEP BLOCK
STEP BY STEP GUIDE - PICTORIAL DRAWINF OF STEP BLOCK
CIRCLES AND ARC IN PICTORIAL DRAWING
CIRCLES AND ARC IN PICTORIAL DRAWING
TYPES OF PICTORIAL DRAWING
TYPES OF PICTORIAL DRAWING
OBJECTIVES
At the end of the lesson students should be able to:
identify and describe various types of pictorial drawings;
know the importance of pictorial drawings:
create isometric, oblique and perspective drawing.
PICTORIAL DRAWING
PICTORIAL DRAWING
Pictorial drawing is an essential part of graphic language. Pictorial drawing provides a 3D image to help understand the shape of an object or to assist in interpreting a drawing.
Pictorial drawings are not often used for construction purposes. However, on some working drawings pictorial views are used to reveal information that orthographic views alone would be incapable of showing; other situations may require a pictorial drawing essentially to supplement a major view. Pictorial projection, unlike multi-view projection, is designed to allow the viewer to see all three primary dimensions of the object in the projection. Pictorial architectural drawings and renderings are very easy to understand and are therefore used extensively to depict a three-dimensional view of an object and for explaining project designs to laypersons for sales-presentation purposes. They enable an inexperienced person to interpret drawings and quickly visualize the shape of individual parts or various components in complicated mechanisms. To convey as much information as possible, the view is oriented to show the sides with the most features.
3 MAIN WAYS TO DRAW A PICTORIAL DRAWING
3 MAIN WAYS TO DRAW A PICTORIAL DRAWING
NOTE: CLICK on the TEXT to view CONTENT.
· Isometric Drawing
· Oblique Projection
· Perspective Drawing
ISOMETRIC DRAWING
ISOMETRIC DRAWING
An Isometric drawing is a pictorial representation of an object in which all three dimensions are drawn at full scale. The term isometric means “equal measurement”.
Isometric drawing is the most commonly used method of pictorial drawing. Isometric drawings are built on three lines, called isometric axes. One is drawn vertically and the other two with the 30° set square either side of it. An Isometric drawing is a way of presenting designs in three dimensions (3D). They can be completed using the 30/60 set square or freehand. An Isometric drawing is one of a family of three-dimensional views called pictorial drawings. In an isometric drawing, the object’s vertical lines are drawn vertically, and the horizontal lines in the width and depth planes are shown at 30 degrees to the horizontal. The true dimension of the object is used to construct the drawing. These dimension can be taken from either a drawings completed in orthographic or by measuring an object. Isometric drawings or images have become the industry standard for parts manuals, technical proposals, patent illustrations and maintenance publications due to their use of true length and the ability for untrained people to understand. An isometric projection results if the plane is oriented so that it makes equal angles with the three principal planes of the object.
OBLIQUE DRAWING
OBLIQUE DRAWING
Oblique projection is probably the simplest method of producing a pictorial drawing because surfaces are directly in front of the viewer will look very similar to the front view in an orthogonal drawing. It is a method of drawing objects in 3 dimensions and may be drawn at any angle although 45⁰ is generally used. It is quite a simple technique compared to isometric or even perspective drawing. However, to draw accurately in oblique projection traditional drawing equipment is needed. Oblique projections illustrate the general 3 dimensional shape of the object. However only faces of the object parallel to the plane of projection are shown at its true size and shape. In fact, the oblique projection of these faces is the same as an orthographic front view.
TWO SPECIFIC FORMS OF OBLIQUE DRAWINGS
TWO SPECIFIC FORMS OF OBLIQUE DRAWINGS
Cavalier and Cabinet Projection
These are Cavalier and Cabinet projection. The difference between the two is how the depth of the object is represented. A cavalier projection is obtained when the angle between oblique projectors and the plane of projection is 45⁰ and the rear projections are true to size. The resulting figure appears too thick and distorted. A cabinet projection is used to correct this deficiency. Cabinet projection is an oblique projection where the length of the lines projecting backwards are halved.
PERSPECTIVE DRAWING
PERSPECTIVE DRAWING
Perspective Drawing is one of the best types of drawings to use to provide a pictorial representation of an object. They produce an image of an object in three dimensions that is very similar to what the human eye sees. Perspective drawings can be in one point, two point or three-point perspective. One of the most common uses of perspective drawing is in architecture, where it is used to provide a client, or the public, an image that gives a good representation of how the project will look when it is built. One-point perspective is often used to represent a room on paper. As well as architecture, perspective drawing is often used in the furniture industry to show clients the final appearance of a piece of furniture they might commission.
GENERAL PRINCIPLES
GENERAL PRINCIPLES
The observer's eye
The object being viewed
The plane of projection
The projectors from the observer's eye to all points on the object
Perspective of a Prism
POSITION OF THE STATION POINT
POSITION OF THE STATION POINT
The center line of the cone of visual rays should be directed toward the approximate center, or center of interest, of the object. In two-point perspective, the type shown in the given figure, the location of the station point (SP) in the plan view should be slightly to the left, not directly in front of the center of the object, and at such a distance that the object can be viewed at a glance without turning the head. This is accomplished if a cone of rays with its vertex at SP and a vertical angle of about 30 degree entirely closes the object.
In the perspective portion of the given figure, SP does not appear because the station point is in front of the picture plane. However, the orthographic projection CV of SP in the picture plane does not show the height of the station point with respect to the ground plane. Since the horizon is at eye level, it also shows the altitude of the station point.
Therefore, in the perspective portion of the drawing, the horizon is drawn a distance above the ground line at which it is desired to assume to the station point. For most small and medium-size objects, such as machine parts or furniture, the station point is best assumed slightly above the top of the object. Large objects, such as buildings. are usually viewed from a station point about the altitude of the eye above the ground or about 5'-6".
LEARNING ACTIVITY
LA-LESSON-6.docxREFERENCES:
CONTENT SOURCE:
CONTENT SOURCE:
Manaois, German M. Drafting Volume 2: Phoenix Publishing House, Inc., 1983, Reprinted 2004
Manaois, German M. Drafting Volume 2: Phoenix Publishing House, Inc., 1983, Reprinted 2004
Brown, W. C. (1994). Drafting for Industry /by Walter C. Brown. Goodheart-Willcox.
Brown, W. C. (1994). Drafting for Industry /by Walter C. Brown. Goodheart-Willcox.
Giesecke, Mitchell, Spencer, Hill, Dygdon, Novak (2003) Pearson Education Inc. - Technical Drawing Twelfth Edition
Giesecke, Mitchell, Spencer, Hill, Dygdon, Novak (2003) Pearson Education Inc. - Technical Drawing Twelfth Edition
VIDEO:
URL: https://youtu.be/eIPHvDcMx-w
URL: https://youtu.be/zjQHPBkW5wo
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