Perspective made easy

Perspective sounds like geometry class, like rulers and exact angles. For urban sketching you only need a small, practical slice of it. This lesson shows you the rules of thumb that make your streets and buildings look right, without ever reaching for a ruler.

The horizon line: your starting point

Every perspective begins with your eye level, also called the horizon line. Imagine an invisible, horizontal line running across the picture exactly at the height of your eyes. Everything above this line – a tall roof, for example – slopes slightly downwards towards the horizon line in your drawing. Everything below it, such as the bottom edge of a front door, rises slightly upwards towards the horizon line. Only what sits exactly at eye level stays a true horizontal.

Establish the horizon line first of all, before you draw a single contour. If you're sitting, it lies lower in the picture; if you're standing, higher. If you're sitting on a first-floor terrace looking down at the street, it even lies above the buildings in front of you. Feel free to sketch the horizon line very lightly in pencil – it will disappear under the paint later.

One vanishing point for the street

A straight street leading away from you into the distance follows the simplest form of perspective: a single vanishing point. All the lines that run parallel to the street in reality – kerbs, facade lines, tram tracks – converge on a single point on the horizon line in your drawing. The further an edge is from the viewer, the closer it moves towards this vanishing point.

For a sketch you don't need to mark the vanishing point precisely. It's enough to imagine roughly where it lies and to aim all the street lines loosely towards it. Only the direction matters: lines running away from the viewer never get steeper, they get flatter the further they move from the eye.

Two vanishing points for a building corner

If you're standing at an angle to the corner of a building, you see two sides of the facade at once – and that means you need two vanishing points, one to the left and one to the right on the horizon line, often far beyond the edge of your paper. The vertical edge of the building corner does stay vertical, and it's your only fixed anchor. From there the facade lines run off to the left towards one vanishing point and to the right towards the other.

Here too, a feel for the direction is enough. Draw the vertical corner edge first, then feel your way towards both facades with gently sloping lines. Windows and doors on both sides follow the same slope as the facade line they belong to, otherwise they look warped.

Measuring with your pencil

To estimate proportions without calculating, stretch out your arm and hold the pencil vertically in front of your subject. Close one eye. Use your thumb to measure how many pencil lengths a window height or a building width takes up, and compare that size with other elements in the picture. That's how you find out, for example, that a door is about two and a half window heights tall, or that a tower is three times as high as the house next to it. You then transfer these comparative values straight onto the paper without ever knowing a single measurement in centimetres.

Typical mistakes and how to avoid them

The most common mistake is roofs that are too steep: beginners often draw gabled roofs far more pointed than they really are, because the eye overestimates slopes. Deliberately look twice and compare the roof angle with an imaginary horizontal before you commit to it. A second classic is windows that don't follow the vanishing line within the facade and therefore seem to tip out of the wall. Consciously align every window element with the slope of the facade line it sits on. And third: a wrongly placed horizon line makes the whole scene wobbly, even if every single line is correct in itself. So really do establish it first.

Exercise

Find a street outdoors or from your window with a visible vanishing line, or a building corner that you see at an angle. First draw the horizon line very lightly at eye level. Then use your outstretched pencil to determine two or three size relationships, such as window height to building height. Draw the scene with your fineliner, consciously aligning every line towards the imagined vanishing point. Give yourself 15 to 20 minutes for this.

Key points

Establish the horizon line at eye level first of all; everything else is aligned to it. Parallel lines receding into the distance converge on one vanishing point, at a building corner there are two. Measure with an outstretched pencil instead of guessing proportions, and pay particular attention to roof angles.