4- The Theory of Projection
-
Upload
api-3815216 -
Category
Documents
-
view
5.091 -
download
7
Transcript of 4- The Theory of Projection
![Page 1: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/1.jpg)
The theory of projectionThe theory of projection
KCEC1101 CAD
![Page 2: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/2.jpg)
ProjectionsProjections
Perspective or Perspective or Central Central
ProjectionsProjections
Parallel Parallel ProjectionsProjections
Linear Linear PerspectivesPerspectives
Aerial Aerial PerspectivesPerspectives
Oblique Oblique ProjectionsProjections
Orthographic Orthographic ProjectionsProjections
Projection MethodsProjection Methods
![Page 3: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/3.jpg)
Projection MethodProjection MethodPerspective or Central Perspective or Central
ProjectionsProjections
Linear PerspectivesLinear Perspectives Aerial PerspectivesAerial Perspectives
![Page 4: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/4.jpg)
Projection MethodsProjection MethodsParallel ProjectionsParallel Projections
Oblique Oblique ProjectionsProjections
Orthographic ProjectionsOrthographic ProjectionsAxonometric Axonometric ProjectionsProjections
MultiviewMultiviewProjectionsProjections
![Page 5: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/5.jpg)
The attributes of each projection methodThe attributes of each projection method
![Page 6: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/6.jpg)
Projection theoryProjection theory
Line of Sight (LOS)A LOS is an imaginary ray of light between an observer's eye and an object.
![Page 7: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/7.jpg)
Projection theoryProjection theoryIn perspective projection, all LOS start at a single point
![Page 8: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/8.jpg)
Projection theoryProjection theoryIn parallel projection, all LOS are parallel and no start point (infinitive viewpoint)
![Page 9: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/9.jpg)
• A plane of projection is an imaginary flat plane upon which the image created by LOS is projected.
Projection theoryProjection theory
![Page 10: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/10.jpg)
MultiviewMultiview projection planesprojection planes1. The frontal plane of projection is the plane onto which the
front view of multiview is projected.
![Page 11: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/11.jpg)
MultiviewMultiview projection planesprojection planes2. The top view is projected onto the horizontal plane of projection,
which is a plane suspended above and parallel to the top object.
![Page 12: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/12.jpg)
MultiviewMultiview projection planesprojection planes3. 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.
![Page 13: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/13.jpg)
It produce the true dimensions !!!It produce the true dimensions !!!
Advantage of Advantage of multiviewmultiview drawingdrawing
Multiview drawing
Distorted angle
Distorted dimension
![Page 14: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/14.jpg)
The six principal of viewsThe 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
![Page 15: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/15.jpg)
The six perpendicular plane of viewsThe six perpendicular plane of views
![Page 16: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/16.jpg)
Conventional view placementConventional view placementConventionally, 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.
![Page 17: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/17.jpg)
Projection dimensionsProjection dimensionsThe 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.
![Page 18: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/18.jpg)
Projection arrangementProjection arrangement
The arrangement of views may vary as long as the dimension alignment is correct.
![Page 19: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/19.jpg)
FirstFirst--Angle ProjectionAngle ProjectionFirst angle projection is the standard in Europe and Asia.
![Page 20: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/20.jpg)
ThirdThird--Angle ProjectionAngle ProjectionThird angle projection is the standard projection for the United States and Canada.
![Page 21: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/21.jpg)
The principal projection planes and quadrants used to create first- and third- angle projection drawings
Profile plane
The difference between first and third angle projection is the placement of the object and the projection plane
![Page 22: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/22.jpg)
Pictorial comparison between firstPictorial comparison between first-- third angle third angle projection techniquesprojection techniques
![Page 23: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/23.jpg)
First angle projectionFirst angle projection
The dihedral anglesThe dihedral angles
First angles projection boxFirst angles projection box
![Page 24: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/24.jpg)
First angle projectionFirst angle projectionFirst angles projection boxFirst angles projection box
Box unfoldingBox unfolding
![Page 25: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/25.jpg)
First angle projectionFirst angle projectionBox unfoldingBox unfolding
Box unfolded show Box unfolded show relative position of view relative position of view
Placement of 1Placement of 1stst
angle of viewangle of view
![Page 26: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/26.jpg)
Third angle projectionThird angle projection
The dihedral anglesThe dihedral angles
Third angles projection boxThird angles projection box
![Page 27: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/27.jpg)
Third angle projectionThird angle projection33rdrd angles projection boxangles projection box
Box unfoldingBox unfolding
![Page 28: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/28.jpg)
Third angle projectionThird angle projection
Box unfoldingBox unfolding
Box unfolded Box unfolded show relative show relative
position of position of view view
Placement of 3Placement of 3rdrd angle of viewangle of view
![Page 29: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/29.jpg)
The rule of orthographic The rule of orthographic projection principles projection principles
1. Alignment of features2. Distances in related views3. True length and size4. Foreshortening5. Configuration of planes6. Parallel features7. Edge views
![Page 30: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/30.jpg)
Rule 1: Alignment of featuresRule 1: Alignment of features
• 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
Every point or feature in one view must be aligned
on a parallel projector
![Page 31: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/31.jpg)
Rule 2: Distances in related viewsRule 2: Distances in related views
• 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
Distances between any two points of the feature in
related views must be equal
![Page 32: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/32.jpg)
Rule 3: True Rule 3: True length and sizelength 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
![Page 33: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/33.jpg)
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
![Page 34: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/34.jpg)
Rule 4: ForeshorteningRule 4: ForeshorteningFeatures 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
![Page 35: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/35.jpg)
Rule 5: Configuration of planesRule 5: Configuration of planesAreas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge
Surface B and C are an example of the Rule of Configuration of planes
Oblique surface
Incline surface
![Page 36: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/36.jpg)
Rule 6: Parallel featuresRule 6: Parallel featuresParallel 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.
![Page 37: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/37.jpg)
Rule 7: Edge viewRule 7: Edge viewSurfaces 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.
![Page 38: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/38.jpg)
Example of normal face projectionExample of normal face projection
A normal face projects on all three principle image planes. (follow the rule of edges view)
![Page 39: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/39.jpg)
Creating a Creating a treetree--view view
sketchsketch
![Page 40: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/40.jpg)
Example of representing filleted and rounded cornersExample of representing filleted and rounded corners
![Page 41: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/41.jpg)
Example of Example of RunoutsRunouts
![Page 42: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/42.jpg)
Representing the intersection of two cylindersRepresenting the intersection of two cylinders
Small cylinder Large cylinder(same size)
![Page 43: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/43.jpg)
Representing the intersection btw a Representing the intersection btw a cylinder and a prismcylinder and a prism
Small prism Large prism
![Page 44: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/44.jpg)
Representing the intersection btw a cylinder Representing the intersection btw a cylinder and a holeand a hole
![Page 45: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/45.jpg)
Representing the intersection btw a cylinder Representing the intersection btw a cylinder and a slotand a slot
![Page 46: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/46.jpg)
Center linesCenter lines
![Page 47: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/47.jpg)
Good & Poor OrientationGood & 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.
![Page 48: 4- The Theory of Projection](https://reader030.fdocuments.net/reader030/viewer/2022020122/5528c1734a7959d83d8b47f5/html5/thumbnails/48.jpg)
EndEnd