4- The Theory Of Projection 4o5z2v
This document was ed by and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this report form. Report 3i3n4
Overview 26281t
& View 4- The Theory Of Projection as PDF for free.
More details 6y5l6z
- Words: 1,059
- Pages: 48
The theory of projection KCEC1101 CAD
Projection Methods Projections Perspective or Central Projections
Linear Perspectives
Aerial Perspectives
Parallel Projections
Oblique Projections
Orthographic Projections
Projection Method Perspective or Central Projections Linear Perspectives
Aerial Perspectives
Projection Methods Parallel Projections Oblique Projections
Axonometric Projections
Orthographic Projections Multiview Projections
The attributes of each projection method
Projection theory
Line of Sight (LOS) A LOS is an imaginary ray of light between an observer's eye and an object.
Projection theory In perspective projection, all LOS start at a single point
Projection theory In parallel projection, all LOS are parallel and no start point (infinitive viewpoint)
Projection theory • A plane of projection is an imaginary flat plane upon which the image created by LOS is projected.
Multiview projection planes 1. The frontal plane of projection is the plane onto which the front view of multiview is projected.
Multiview projection planes 2. The top view is projected onto the horizontal plane of projection, which is a plane suspended above and parallel to the top object.
Multiview projection planes 3. The right side is projected onto the right profile plane of projection, which is a plane that is parallel to the right side of the object.
Advantage of multiview drawing It produce the true dimensions !!! Distorted angle
Distorted dimension
Multiview drawing
The six principal of views 1.
The front view
2.
The top view
3.
The right side view
4.
The left side view
5.
The rear view
6.
The bottom view
The six perpendicular plane of views
Conventional view placement Conventionally, the standard views used in a three-view drawing are the top, front, and right side view. Because the other three principal views are mirror image and do not add to the knowledge about the object.
Projection dimensions The width dimension is common to the front and top views. The height dimension is common to the front and side views. The depth dimension is common to the top and side views.
Projection arrangement
The arrangement of views may vary as long as the dimension alignment is correct.
First-Angle Projection First angle projection is the standard in Europe and Asia.
Third-Angle Projection Third angle projection is the standard projection for the United States and Canada.
Profile plane
The difference between first and third angle projection is the placement of the object and the projection plane The principal projection planes and quadrants used to create first- and third- angle projection drawings
Pictorial comparison between first- third angle projection techniques
First angle projection
The dihedral angles
First angles projection box
First angle projection First angles projection box
Box unfolding
First angle projection
Box unfolding
Box unfolded show relative position of view Placement of 1st angle of view
Third angle projection
The dihedral angles
Third angles projection box
Third angle projection 3rd angles projection box
Box unfolding
Third angle projection Box unfolding
Placement of 3rd angle of view
Box unfolded show relative position of view
The rule of orthographic projection principles 1. 2. 3. 4. 5. 6. 7.
Alignment of features Distances in related views True length and size Foreshortening Configuration of planes Parallel features Edge views
Rule 1: Alignment of features Every point or feature in one view must be aligned on a parallel projector •
•
For example, the hole in the block is an example of a feature shown in one view and aligned on parallel projectors in the adjacent view Adjacent views are two orthographic view placed next to each other such that the dimension they share in common is aligned, using parallel projectors. hole feature
Rule 2: Distances in related views Distances between any two points of the feature in related views must be equal •
•
For example, the distance between surface 1 and surface 2 is the same in the top view as it is in the right side view. Two views that are adjacent to the same view are called related views
Rule 3: True length and size
For example edge 1-2 in the top and right side view is a normal edge (or true-length line)
Features are true length or true size when the lines of sight (LOS) are perpendicular to the feature
An inclined line is parallel to a plane of projection, but inclined to the adjacent planes, it appears foreshortened in the adjacent planes.
For example line 3-4 is inclined and foreshortened in the top and right side view, but true length in the front view, because it is parallel to the frontal plane of projection
Rule 4: Foreshortening Features are foreshortening when the line of sight are not perpendicular to the features •
For example oblique line 1-2 is not parallel to any of the principal planes of projection of the glass box.
•
An oblique line is not parallel to any principal plane of projection
Rule 5: Configuration of planes
Oblique surface
Areas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge
Incline surface
Surface B and C are an example of the Rule of Configuration of planes
Rule 6: Parallel features Parallel features will always appear parallel in all views
For example, at surface C, lines 3-4 and 5-6 are parallel in all views (front, top and right). Also, edge 3-6 and 4-5 are parallel in both the top view and the right view.
Rule 7: Edge view Surfaces that are parallel to the lines of sight will appear on edge and be represented as lines.
For example, surface A, C, D and F are parallel to the line of sight and will appear as on edges which represented as lines at projected front view.
Example of normal face projection A normal face projects on all three principle image planes. (follow the rule of edges view)
Creating a tree-view sketch
Example of representing filleted and rounded corners
Example of Runouts
Representing the intersection of two cylinders
Small cylinder
Large cylinder (same size)
Representing the intersection btw a cylinder and a prism
Small prism
Large prism
Representing the intersection btw a cylinder and a hole
Representing the intersection btw a cylinder and a slot
Center lines
Good & Poor Orientation
The major surface are parallel or perpendicular to the sides of the box (projections planes)
The surface are not parallel to the sides of the glass box produces views with many hidden lines.
End
Projection Methods Projections Perspective or Central Projections
Linear Perspectives
Aerial Perspectives
Parallel Projections
Oblique Projections
Orthographic Projections
Projection Method Perspective or Central Projections Linear Perspectives
Aerial Perspectives
Projection Methods Parallel Projections Oblique Projections
Axonometric Projections
Orthographic Projections Multiview Projections
The attributes of each projection method
Projection theory
Line of Sight (LOS) A LOS is an imaginary ray of light between an observer's eye and an object.
Projection theory In perspective projection, all LOS start at a single point
Projection theory In parallel projection, all LOS are parallel and no start point (infinitive viewpoint)
Projection theory • A plane of projection is an imaginary flat plane upon which the image created by LOS is projected.
Multiview projection planes 1. The frontal plane of projection is the plane onto which the front view of multiview is projected.
Multiview projection planes 2. The top view is projected onto the horizontal plane of projection, which is a plane suspended above and parallel to the top object.
Multiview projection planes 3. The right side is projected onto the right profile plane of projection, which is a plane that is parallel to the right side of the object.
Advantage of multiview drawing It produce the true dimensions !!! Distorted angle
Distorted dimension
Multiview drawing
The six principal of views 1.
The front view
2.
The top view
3.
The right side view
4.
The left side view
5.
The rear view
6.
The bottom view
The six perpendicular plane of views
Conventional view placement Conventionally, the standard views used in a three-view drawing are the top, front, and right side view. Because the other three principal views are mirror image and do not add to the knowledge about the object.
Projection dimensions The width dimension is common to the front and top views. The height dimension is common to the front and side views. The depth dimension is common to the top and side views.
Projection arrangement
The arrangement of views may vary as long as the dimension alignment is correct.
First-Angle Projection First angle projection is the standard in Europe and Asia.
Third-Angle Projection Third angle projection is the standard projection for the United States and Canada.
Profile plane
The difference between first and third angle projection is the placement of the object and the projection plane The principal projection planes and quadrants used to create first- and third- angle projection drawings
Pictorial comparison between first- third angle projection techniques
First angle projection
The dihedral angles
First angles projection box
First angle projection First angles projection box
Box unfolding
First angle projection
Box unfolding
Box unfolded show relative position of view Placement of 1st angle of view
Third angle projection
The dihedral angles
Third angles projection box
Third angle projection 3rd angles projection box
Box unfolding
Third angle projection Box unfolding
Placement of 3rd angle of view
Box unfolded show relative position of view
The rule of orthographic projection principles 1. 2. 3. 4. 5. 6. 7.
Alignment of features Distances in related views True length and size Foreshortening Configuration of planes Parallel features Edge views
Rule 1: Alignment of features Every point or feature in one view must be aligned on a parallel projector •
•
For example, the hole in the block is an example of a feature shown in one view and aligned on parallel projectors in the adjacent view Adjacent views are two orthographic view placed next to each other such that the dimension they share in common is aligned, using parallel projectors. hole feature
Rule 2: Distances in related views Distances between any two points of the feature in related views must be equal •
•
For example, the distance between surface 1 and surface 2 is the same in the top view as it is in the right side view. Two views that are adjacent to the same view are called related views
Rule 3: True length and size
For example edge 1-2 in the top and right side view is a normal edge (or true-length line)
Features are true length or true size when the lines of sight (LOS) are perpendicular to the feature
An inclined line is parallel to a plane of projection, but inclined to the adjacent planes, it appears foreshortened in the adjacent planes.
For example line 3-4 is inclined and foreshortened in the top and right side view, but true length in the front view, because it is parallel to the frontal plane of projection
Rule 4: Foreshortening Features are foreshortening when the line of sight are not perpendicular to the features •
For example oblique line 1-2 is not parallel to any of the principal planes of projection of the glass box.
•
An oblique line is not parallel to any principal plane of projection
Rule 5: Configuration of planes
Oblique surface
Areas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge
Incline surface
Surface B and C are an example of the Rule of Configuration of planes
Rule 6: Parallel features Parallel features will always appear parallel in all views
For example, at surface C, lines 3-4 and 5-6 are parallel in all views (front, top and right). Also, edge 3-6 and 4-5 are parallel in both the top view and the right view.
Rule 7: Edge view Surfaces that are parallel to the lines of sight will appear on edge and be represented as lines.
For example, surface A, C, D and F are parallel to the line of sight and will appear as on edges which represented as lines at projected front view.
Example of normal face projection A normal face projects on all three principle image planes. (follow the rule of edges view)
Creating a tree-view sketch
Example of representing filleted and rounded corners
Example of Runouts
Representing the intersection of two cylinders
Small cylinder
Large cylinder (same size)
Representing the intersection btw a cylinder and a prism
Small prism
Large prism
Representing the intersection btw a cylinder and a hole
Representing the intersection btw a cylinder and a slot
Center lines
Good & Poor Orientation
The major surface are parallel or perpendicular to the sides of the box (projections planes)
The surface are not parallel to the sides of the glass box produces views with many hidden lines.
End
Related Documents 3h463d
4- The Theory Of Projection 4o5z2v
October 2019 38
Theory Of Orthographic Projection 3z736j
April 2020 30
Theory Of Projection Pdf 5v4v5d
November 2019 55
Feldman - Projection 4 223724
October 2019 51
4 Market Projection Method 71i49
April 2021 0