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CONVERGING PROJECTION SYSTEMS ORPERSPECTIVE

Perspective is vital with any technical drawing.Perspective establishes a viewer’s cone ofvision and a context for objects containedwithin it. For example, a representationconstructed on a picture plane has anestablished ground and horizon upon whichobjects can be placed in relation to it.Perspective is distinct from the other drawingsystems we have been looking at in that itcreates an illusory yet real impression of spacewhich employs an imaginary or observed viewcreated purely through our observation of asubject. These two systems employ the samerules, although they arise from different

creative roots and needs. The constructedperspective drawing is dominated by puretheory; the observed perspective drawing isfrom one view point. Perspective is a system ofdrawing that shows the illusion of three-dimensional objects in a picture space. Toproduce a good perspective drawing one has toabide by a certain set of rules. To break theserules is to undo the illusion.

There are two common uses for perspective.One is a perspective drawing constructed fromour imagination and creative thoughts; theother is constructed from an understanding ofplanal recession and form.

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Part One – THE PENCIL

ONE-POINT PERSPECTIVE

These are the basic rules that govern a one-point perspective drawing, and it is worthremembering that all lines that do notappertain to the horizontal or the vertical axiswill go back to or terminate at the perspectivalpoint that as been set up in this drawing.

1/ Draw a square on your piece of paper justto the left or the right of the centre of yourpiece of paper. Make sure that this square runsparallel to the edges of the paper.

2/ Now draw a horizontal line across the pieceof paper that travels through the square. Thiswill be referred to as the horizon line, and indrawings from observation it can be referredto as your eye level.

3/ Put a dot on the horizon line that sits on theother side of the paper to the square you havejust drawn. This is now known as the vanishingpoint.

4/ From the nearest top and bottom side ofthe square draw two straight lines thatconverge to the vanishing point. It isimportant that extreme accuracy be observedin drawings of this type, as any slight mistakescan lead to distortion in the drawings.Therefore, I would advise that beginners use aruler for this part of the operation.

Now do the same from the top and bottomof the far end of the square. You will now havea drawing that resembles the example at thebottom of the page.

5/ The next step is to place the back end of thebox in. Do this by drawing in a verticalbetween the set of converging lines that weestablished in step 4. You need to place theline purely visually to make the illusion of thebox. Place the line too far away and youproduce an oblong lying down, and place theline to close and you produce an oblong

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standing up. So try to place the line so it makesthe illusion of a cube.

6/ Now draw two horizontal lines from the topand the bottom of this vertical line that you haveestablished as the back of the box so as they joinup with the two converging lines that run fromthe other side of the box to the vanishing point.

7/ Now draw your final vertical line to establishthe complete box in a one-point perspective.

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Other examplesof one-pointperspective.

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Part One – THE PENCIL

TWO-POINT PERSPECTIVE

1/ In two-point perspective the drawingtheory is very much the same. The differenceis that the box or cube is set in a differentorientation to the picture plane – instead ofdrawing a square in a facing position orrunning parallel to the picture plane, as wedid in step one for the one point perspectivedrawing. We instead draw a vertical line justto the left or right of centre.

2/ Now put in the horizon line that, for thesake of this example, makes this line cutthrough the vertical line just above half way,and it should travel from one end of thepaper to the other. For other practiceexamples, you can be diverse as to where

you put the horizon line to experience thedynamics of perspective space.3/ Place two vanishing points on this line oneat one edge of the paper and the other at theother edge of the paper.

4/ As with step four of the one pointperspective now draw a line from the topand the bottom of the vertical to thevanishing points on both sides. Againaccuracy is paramount in this type ofdrawing.

5/ You need now to visually place the backends of the box in. Do this by placing avertical line on one side of the originalvertical so as it fits between the converging

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lines and it gives the appearance of beingbox shaped. Then repeat the process on theother side of the original vertical. You willnow have created a box in a twistedorientation using two-point perspective.

6/ As with the one-point perspective we needto create the illusion of the back of the box.To do this draw two lines from the far lefthand vertical to the vanishing point on theright-hand side this is shown as a dotted linein the example.

7/ Now do the same from the vertical line onthe right hand side. Draw two lines from thetop and bottom of this vertical that willextend back to the vanishing point on theleft hand side.

8/ Finally, to finish off this drawing, all youneed to do is to draw a vertical line betweenthe two points at which they cross at theback of the box.

It is possible, using the same process butchanging the vanishing points, to createmany boxes in different orientations on thesame picture. This process described herehas also been used in the observedperspective drawing, but the vanishingpoints and horizon line or eye level is foundthrough calculation from our observation.

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Part One – THE PENCIL

OBSERVED PERSPECTIVE

When drawing perspective from observationyou must be able to accurately measure theangles. To start the drawing first establish yourcomposition through your window mount.Once you are happy with your position,establish the first major vertical in thecomposition. From this we can establish thehorizon line or your eye level. It is importantthat you keep this view constant while you areengaged in the drawing, otherwise you willexperience distortion.

1/ Start your drawing by assessing where youthink your primary vertical is situated.Establish it first, as you will be making yourmajor perspectival assessments from it. In thefirst example you can see that the corner ofthe building in the row of houses is our mainpoint of departure. So draw the vertical inposition accurately first. In our drawing, wehave now established where the corner of thehouse is and its height.

2/ From that corner we can now begin toconstruct the perspective structure, andestablish our eye level in the drawing. To dothis we need to begin to assess the angles fromthe top and the bottom of the verticals. We cando this as we did for the posture lines, holdingthe pencil on the angle of the building andthen transporting this angle to both the topand bottom of the vertical line. If you find thisprocess particularly difficult, you can use a

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form of geometry to establish the angles. Aswith the example of the isometric drawing, Ihave established the 30° angle from using a 90°right angle. You can place a right angle to thevertical and then make an approximation as tothe angle of your observation. When you feelconfident that the angles of the lines you areabout to draw are right, use a ruler to drawthem to the point where they converge. At thispoint you will have established for thatbuilding or object one of its vanishing points.It is on this point also that the horizon line, orthe eye level, is established. Now you can drawin the eye level line by simply making ahorizontal line across your paper. There is asimple rule to remember for perspective. Allthe perspective lines that are above eye levelwill converge downward to a particularvanishing point on the horizon line. The sameis true for those perspective lines that liebelow the eye level, only they will convergeupwards to the horizon line to a particularvanishing point. The accuracy of thesemeasured angles is vital to the success of thedrawing. Once you have the two converginglines from your first vertical, you can use themas guides to draw the rest of the building.

3/ Decide how long the front face of thebuilding is by looking back at the compositionthrough the window mount. Put in a verticalline to denote the end of the building. This will

fit exactly between the two converging lines togive us the correct perspective. One can nowdo the same to the other side of the building,using the same process. However, you willnotice that the perspective point on thisoccasion goes off the other side of the picture.Do not worry about this – it happens in mostperspective drawings. In this detail we haveextended the drawing perspectivally forwardto draw the row of houses in the foreground.This has been achieved by extending theperspective lines that come from thevanishing point on the horizon line, and thenplacing the vertical line in to denote the edgeof the building.

4/ Add the roof and the chimney pots so thebuilding now has its basic structure.

5/ Architectural information such as doors,windows and pavements are now put in.

6/ We have now established the perspectivalbasis of the composition. At this stage yourdrawing will lack expression or character. Inthis final stage we need to put in the elementsthat make the drawing more real, such as thevan, the telegraph poles, the curving side ofthe road, and the other houses in thebackground. Finally, it all needs to be broughtto life by working over the top of theperspective with free, gestural lines.

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Part One – THE PENCIL

Observed perspective

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