Orthographic Projection
The orthographic projection shows the object as it looks from the front, right, left, top, bottom, or back, and are typically positioned relative to each other according to the rules of either first angle or third angle projection. The origin and direction of the projectors (also called projection lines) differs between the two systems.
For both systems the term orthograhic means to produce a graphic (drawing) at 90 degrees (orthogonally) from the original drawing view.
Not all views are necessarily used. Generally only as many views are used as are necessary to convey all needed information clearly and economically. The front, top, and right-side views are commonly considered the core group of views included by default, but any combination of views may be used depending on the needs of the particular design. In addition to the 6 principal views (front, back, top, bottom, right side, and left side), any auxiliary views or sections may be included as serve the purposes of part definition and its communication. View lines or section lines (lines with arrows marked "A-A", "B-B", etc.) define the direction and location of viewing or sectioning. Sometimes a note tells the reader in which zone(s) of the drawing to find the view or section.
For both systems the term orthograhic means to produce a graphic (drawing) at 90 degrees (orthogonally) from the original drawing view.
Not all views are necessarily used. Generally only as many views are used as are necessary to convey all needed information clearly and economically. The front, top, and right-side views are commonly considered the core group of views included by default, but any combination of views may be used depending on the needs of the particular design. In addition to the 6 principal views (front, back, top, bottom, right side, and left side), any auxiliary views or sections may be included as serve the purposes of part definition and its communication. View lines or section lines (lines with arrows marked "A-A", "B-B", etc.) define the direction and location of viewing or sectioning. Sometimes a note tells the reader in which zone(s) of the drawing to find the view or section.
First Angle Projection
The symbol for First Angle Projection. The left hand view is draw as if the reader was looking through the front view from the right hand side. The left hand view shows the right hand side.
An easy way to visualise this method is to imagine the conical shape is standing up in the front view and is knocked over to produce the left hand view.
In first-angle projection, the projectors originate as if radiated from a viewer's eyeballs and shoot through the 3D object to project a 2D image onto the plane behind it. The 3D object is projected into 2D "paper" space as if you were looking at a radiograph of the object: the top view is under the front view; the right view is at the left of the front view. First-angle projection is the ISO standard and is primarily used in Europe.
An easy way to visualise this method is to imagine the conical shape is standing up in the front view and is knocked over to produce the left hand view.
In first-angle projection, the projectors originate as if radiated from a viewer's eyeballs and shoot through the 3D object to project a 2D image onto the plane behind it. The 3D object is projected into 2D "paper" space as if you were looking at a radiograph of the object: the top view is under the front view; the right view is at the left of the front view. First-angle projection is the ISO standard and is primarily used in Europe.
Third Angle Projection
The symbol for Third Angle Projection. The right hand view shows the right hand side. The drawing view is produced on the side being viewed.
In third-angle projection, the projectors originate as if radiated from the 3D object itself and shoot away from the 3D object to project a 2D image onto the plane in front of it. The views of the 3D object are like the panels of a box that envelopes the object and the panels pivot as they open up flat into the plane of the drawing. Thus the left view is placed on the left and the top view on the top; and the features closest to the front of the 3D object will appear closest to the front view in the drawing. Third-angle projection is primarily used in the United States and Canada, where it is the default projection system according to British Standard BS 8888 and ASME standard ASME Y14.3M.
In third-angle projection, the projectors originate as if radiated from the 3D object itself and shoot away from the 3D object to project a 2D image onto the plane in front of it. The views of the 3D object are like the panels of a box that envelopes the object and the panels pivot as they open up flat into the plane of the drawing. Thus the left view is placed on the left and the top view on the top; and the features closest to the front of the 3D object will appear closest to the front view in the drawing. Third-angle projection is primarily used in the United States and Canada, where it is the default projection system according to British Standard BS 8888 and ASME standard ASME Y14.3M.
