Mechanical drawings using a basic perspective grid.
Step-by-step lesson in how to map out a 2-pt perspective drawing from plan & elevation views.
All Tutorial Text & Images - Copyright © 2011 KHI, Inc.
In this step-by-step lesson we are going to create a simple "2 Point Perspective" view drawing of our test subject example, working from both plan (overhead) and elevation view (side view or profile) reference Fig 1. This type of illustration angle is referred to as a "3/4 Perspective" or an "Angular Perspective" view. The green dots in all of the following perspective grid diagrams identify the lines to be drawn as shown in each visual example. This type of perspective grid is best done using vector drawing software such as Adobe Illustrator, where you can easily drag a single anchor-point on each line drawn, rotating it from the other fixed anchor-point to create a "projection line" from the fixed point.
The first line to draw will be the horizontal Picture Plane line shown in Fig. 2. By placing the vertical line (green dot) off-center (to the right) between the two vanishing points we will ultimately see more of the left side of the subject than the right side. Typically, you want about the same amount showing on both the left and right side of the object if it is roughly square (like a laser printer), and a little more showing on the long side of a rectangular object such as a car or ship.
We will place the lower right corner of our Plan View diagram on the horizontal Picture Plane line and rotate it clockwise Fig. 3 while keeping it in contact with the picture plane. The choice of a 30 degree angle for our plan-view diagram is totally arbitrary, but this positioning provides a good final angle for a typical 3/4 view drawing.
The ultimate angle chosen, and the wide-angle or narrow (telephoto) angle of view should balance factors such as the best aesthetics for the subject matter being illustrated, and the necessary technical information (highlighted features) to be conveyed. The subject always dictates the best observing angle chosen. In
In Fig. 4 we will locate the Station Point which will be located directly below to leading edge (lower corner) of the diagonal plan-view. Measure the horizontal width of our Plan View (X) and double it. Extend a vertical line from the corner that touches the Picture Plane downward. At two times "X" we will locate the Station Point.
Draw lines for the Horizon and Ground Line Fig. 5. The location of these lines are infinitely variable, but their location will ultimately determine how high or low the viewer is in relation to the subject. The location of the Ground Line in relation to the Horizon Line will determine how far above or below "eye level" the object will be viewed. The lower the ground line, the higher the viewer is in relation to the subject.
If the ground line was located directly on top of the horizon line the viewer (or camera) would literally be at ground level. The location of the Horizon Line will depend on whether you want to view the object from above eye-level or below eye-level.
Draw 2 lines from the Station Point (SP) that are parallel to the bottom edges of the Plan View Fig 6. The lines should intersect with the Picture Plane (points a & b). Next draw vertical lines from points a & b to the Horizon Line. The point where these vertical lines intersect the Horizon Line is where the left and right vanishing points (LVP & RVP) will be located. The location of the vanishing points will determine how sever the perspective is. The further away they are in relation to the subject, the more "telephoto" the view will be. If the vanishing points are closer to the subject the view will be more like a wide-angle lens.
The last part of our preliminary layout will be to place the Side Elevation view from Fig. 1 onto the Ground Line, with the furthest left edge aligning with the left vanishing point. Project a horizontal line (orange dashed line b) from the top of the Elevation View to the vertical Line of Sight (LS) Fig. 7, below.
We are now ready to start projecting our blue lines to and from the left and right (LVP & RVP) vanishing points. Referring to Fig. 8, draw lines from both vanishing points to the top (uppermost surface) and bottom (lowest, ground level surface) reference points of our subject (points a & b).
To locate each of the vertical lines on our subject, draw lines upward beginning at the Station Point and intersecting with the left and right corners (a & b) on the plan view diagram Fig. 9. At the point where these vertical lines intersect the Picture Plane (c & d), draw vertical lines downward (orange dashed lines) to intersect with the left and right vanishing point's blue projection lines (green dots).
Using the same procedure as shown in Fig. 9, start constructing all of the smaller features on the subject as shown in both the Plan View and the Elevation View (a & c) in Fig. 10. Once located, project these horizontally towards the left and right vanishing points using our blue projection lines. Then connect each parallel and/or perpendicular intersecting point with a vertical line to complete the vertical shape. Continue repeating this process through Fig. 11 until all vertical and horizontal surfaces have been completed.
The last step is to darken the object's construction lines, remove all of the blue projection lines, and add weight ("stroke weight" in Adobe Illustrator) to all of the exterior and outside edge lines of the object, to increase the readability and visual appeal of the drawing Fig. 12.
In the line drawing examples below, the complex technical illustration shown in Fig. 14 was created using a very basic 2-point perspective grid (Fig. 13) as a starting point, then fleshing-out all of the machine's exterior details and constructing all of the internal mechanical information. The master 2-point perspective grid shown in Fig. 13 was used for all of the information shown in Fig. 14.
In this example, we used 2-point perspective because the machine was around 6 feet tall and the horizon line was just above the uppermost vertical point of the subject. By using this angle of view, all of the vertical lines are nearly perpendicular (90°) to the horizon. If the viewing location was any higher (looking down on the subject), or much lower (near ground level, looking upward towards the subject), we would utilize a 3-point perspective grid with a third (vertical) vanishing point above or below the subject.
By learning and following this basic set of fundamental principles you can create 3D perspective illustrations of any subject, regardless of complexity.
Continue to: 3 Point Perspective Drawing Tutorial
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