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Pictorial 3-dimensional representations
one vanishing point lines that are not vertical or horizontal & converge to a single point in distance
Two-point or Three-point
two or three vanishing points with two points, vertical or horizontal lines parallel, but not both With three-point, no lines are parallel.
Drawing shows corner of object, but parallel lines on object are parallel in drawing. Shows three dimensions, but no vanishing point.
ISOMETRIC DRAWING: IT IS A TYPE OF PICTORIAL PROJECTION IN WHICH ALL THREE DIMENSIONS OF AN OBJECT ARE SHOWN IN ONE VIEW AND IF REQUIRED, THEIR ACTUAL SIZES CAN BE MEASURED DIRECTLY FROM IT.
Orthographic view shows only two dimensions in any particular view. This makes it difficult to interpret them and only technically trained person can interpret the meaning of these orthographic views. A non-technical person cannot imagine the shape of the object from orthographic projections. Whereas, pictorial projections can be easily understood even by persons without any technical training because such views show all the three dimensions of an object in the same view. But pictorial view does not show the true shape and size of any principal surface of an object and it does not show the hidden portions. Pictorial projections are easy to imagine so these are normally used.
Isometric Axes: The lines AB, AD and AE meeting at a point A and making an angle of 120o with each other are termed isometric axes Isometric Lines:
The lines parallel to the isometric axes are termed isometric lines. The lines CD, CB etc are examples of isometric lines. Non-isometric Lines:
The lines which are not parallel to isometric axes are termed non-isometric lines. The BD is an example. Isometric Planes:
The planes representing the faces of the rectangular prism as well as other planes parallel to these planes are termed isometric planes.
Isometric Plane and Non-isometric Plane:
Isometric Planes are marked as 1 and Non-isometric Planes are marked as 2 Lecture 3 Tuesday, 04 March 2014 8
Isometric Projection: Drawing prepared with isometric scale on isometric axes
Isometric Drawing: Drawing prepared with ordinary scaleon isometric axes
Lecture 3 Tuesday, 04 March 2014 9
Isometric sketches begin with defining isometric axes, three lines, one vertical and two drawn at 30 from the horizontal.
Lecture 3 Tuesday, 04 March 2014 10
Three lines of the isometric axes represent the three primary dimensions of the object: width, height, and depth
Lecture 3 Tuesday, 04 March 2014 11
Draw the font face of the isometric block.
Lecture 3 Tuesday, 04 March 2014 12
Draw the rest of the isometric block.
Lecture 3 Tuesday, 04 March 2014 13
Add details to the block starting from the front face. Then add details to the other faces.
Lecture 3 Tuesday, 04 March 2014 14
Darken all visible lines to complete the isometric sketch. (make sure that construction lines are light)
ORTHOGRAPHIC PROJECTIONS Orthographic Projection is a method of representing a three dimensional object on
paper using several two dimensional views. It is the international language of Engineers and Designers Orthographic projections are drawings where the projectors, the observer or station
point remain parallel to each other and perpendicular to the plane of projection.
Orthographic Projections are a collection of 2-D drawings that work together to give an accurate overall representation of an object.
Six Principle Views
The 6 views of
Principle Views Front, Right Side
and Top are views that simply represented by rotating the object
Glass Box Most powerful technique to
understand orthographic projections Suspend the object with transparent
strings inside a glass box Freeze the view from each direction
(each of the six sides of the box) and unfold the box