Dihedral system. Base.
dihedral system is a method of representing multiple projections, in which the elements are defined by their orthogonal projections on at least two planes of projection.
projection planes that we use typically are 3: plan, elevation and profile . Once you have projected onto each of them the orthogonal views of the object is rotated until they match the three in the same plane.
The cylinder contains a point by point projected on the horizontal and vertical PV PH. As is done with perpendicular, the circumference of the base becomes the standard in a straight line as the plane that contains perpendicular to the vertical.
Being parallel to the floor, the upper surface of the cylinder is transformed this plane into a circle as well.
The line of intersection of vertical and horizontal line is called land.
then turn 90 degrees vertical plane until it coincides with the horizontal axis of rotation taking as the ground line. The rotation causes the two views are perfectly aligned in lines orthogonal to the ground line.
dihedral
The two views (plan and elevation) would be this way. After the rotation of the object dihedral projections are always correlated.
We removed the reference of the outline of the two planes and we already have the plan and elevation. Land line represents dihedral system by a straight line between the plant and the elevation and two segments at the ends.
If the piece has more complexity can be necessary to represent another view in a plane projection. In the figure we see the plane of the profile (PP).
Figure
yellow see in what is projected in the vertical plane, in red and green in horizontal and green on the plane of the profile.
the plant is placed in the orthogonal projection of the piece "seen" from above (in yellow and blue). Correspondingly to the above sum appears that is the front view (orange, green and dark blue) and finally the outline of the piece (in pink), as its name. Non-visible parts of the piece the viewer is positioned as above for the plant, or head to see the elevation appear discontinuous. Dotted lines are lines that exist, which are intersection of surfaces but can not be appreciated for being behind a face.
One piece with their projections in plan, elevation and profile, and axonometric representation after a 90 ° rotation of the same.
The piece, as it has a hollow prism whose edges are tangent to some faces of the figure, these lines appear with a continuous provision because they are visible.
We will represent the dihedral system with another prism prism oblique hollow inside, for that we need two procedures:
one hand we have the European system in which the observer is placed on top of the piece view from above ground. Stands behind the part to see it in the standard or profile. With approach, which viewed from a distant view to avoiding distortion of concurrent lines of perspective, it looks like the orthogonal projections of the object on the three planes of projection.
Once you have designed the three views on the three planes of projection, the profile plane is rotated 90 ° to match it to the the elevation plane. Then the two planes are rotated until they match the plant, all coinciding with the plane of the picture or paper. The turn is always relative to the line of intersection of the planes.
On the other hand we have the American system, in which a representation of the practice excludes the observer, the object is just as if they reflect on the three planes of projection being the mirrors. The image of the three faces of the piece reflected are displayed on the three planes of projection.
For the elevation and profile views, both planes are rotated 90 degrees so that match the floor plan, so are the three dihedral system views. The LT is a line formed by a large segment alternate to two small and so on.
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