2 Methods for Correct Proportions: Sight Size and Comparative Measurement
In realistic drawing, one of the most important factors for a credible depiction is achieving correct proportions. Certain measuring techniques can be very helpful for both beginners and advanced artists. Two essential methods to distinguish are: the so-called "Sight Size" and "Comparative Measurement".
What is it?
What is it?
"Sight Size" is a measuring method where the observed subject is drawn directly on paper at the same size it appears to the artist's eye. Hence the name: "Sight Size" literally means size as seen.
The drawing is created on a 1:1 scale compared to what is seen.
How does "Sight Size" work? Step-by-Step
1. Position your drawing board as straight as possible (90 degrees).
Ensure you and your board are positioned so you see your subject in a format that fits on your paper (or other drawing surface). Depending on which hand you draw with, you should look along the opposite side of the board while drawing and measuring (e.g., as a right-hander, look left). Maintain at least an arm's length distance from your board.
Stand directly in front of your board, with your body centered between your subject and the board. For example, when drawing figures, it may be helpful to overlap the edge of the board with the outermost point of the figure.
Mark your position with tape.
Find a central vertical line through your subject with one eye closed and draw this on your paper. A plumb line can help achieve this straight line.
Now you can measure the important heights of your subject as follows: Stand upright in your position, extend your arms straight in front of you (if using a plumb line as a measuring tool), and close one eye. Align the plumb line with the point whose height you want to transfer and make a mark where the plumb line intersects the vertical line on your paper.
You can do this with each height, but it's helpful to start with the highest and lowest points of your subject and then work through the heights in order of importance.
Check (multiple times) your heights depending on your highest and lowest points.
To measure the most important widths, take the same position and pose as when measuring the heights, close one eye, and determine the distance between the desired point and the imaginary central line of your subject. You can use a measuring tool here: if using a plumb line, use both thumbs to hold the exact distance; if using a stable object (like a pencil, ruler, etc.), use one thumb and the end of the object. Transfer the width by overlapping your measurement over your paper and overlapping one side (either the thumb or the other end) with the vertical line.
You can do this with each width, but it's helpful to start with the widest point of your subject and then work through the widths in order of importance.
Check (multiple times) your widths depending on your widest point.
It is up to you whether to measure all the important heights first and then all the important widths, or to measure them alternately, so that you transfer one point (height and width) after another.
Comparative Measurement, on the other hand, is used when something is seen larger or smaller than it appears in the drawing. This is the case when the subject is very close or very far from the artist. For example, the spatial environment can influence the choice of measuring method - in a small space, you may not be able to move far enough away from the subject to achieve the desired format.
In Comparative, the drawing is always made in a scale of 1:X to what is seen (for mathematicians with X≠1).
How does Comparative Measurement work? Step-by-Step
You can set up your drawing board at a 90-degree angle, but the Comparative method can also be used if, for example, you have your paper lying flat on the table or hold a block on your knees.
Although you may not be able to position yourself and your board to see your subject in a format that fits on your paper, you should still make sure to have a good view of your subject. If you use an upright board, you should look along the opposite side of the board while drawing and measuring (e.g., as a right-hander, look left). You should have about an arm's length distance from your board. A little space behind you can be helpful later for a better comparison of the overall impression when stepping back.
Stand directly in front of your board, with your body centered between your subject and your board.
Mark your position with tape.
Find a central vertical line through your subject with one eye closed and draw this on your paper. A plumb line can help achieve this straight line.
Usually, you start a drawing in Comparative Measurement by determining the highest and lowest points of the subject on the paper. For this, simply choose two points on the paper that fit the desired format of your drawing. These points then serve as the basis for all your further measurements.
Next, determine the most important heights of your subject: Similar to Sight Size, you need to stand in your position, extend your arms with your "measuring tool" in front of you, and close one eye. You then determine the height of the selected point by comparing its distance from the highest and lowest points (distances can be held as with Sight Size or with your thumb). This gives you a length ratio (e.g., 2/3), which you can then transfer to your paper.
Check (multiple times) your length ratio and the resulting mark.
To measure the important widths, take the same position you used for the heights and close one eye. Then you need to find a distance that you have already determined with the heights (e.g., in a portrait: the distance from the highest point to the hairline, from the eyebrows to the tip of the nose, from the nose to the mouth, etc.) to use this as a unit of measurement. Once you have decided on such a unit, you can measure the distance from the imaginary central line of your subject to the point whose width you want to determine (e.g., this could be the width of the cheekbone, 2 eyebrow-to-hairline units). You can then transfer this length ratio to your paper.
You can do this with each width, but it's helpful to start with the widest point of your subject and then work through the widths in order of importance.
Check (multiple times) your length ratio and the resulting mark.
Just like Sight Size, it's basically up to you whether to measure all the important heights first and then all the important widths, or to measure them alternately, so that you transfer one point (height and width) after another, but you should start with the highest and lowest points, as well as an additional height, that can then serve as a unit of measurement for the widths.
Helpful "measuring tools" can include "plumb lines" (lead cords or ropes), as well as wooden skewers, knitting needles or similar thin, stable objects, but also rulers. With such aids, exact or comparative dimensions can be easily taken with the (or the) thumb.
What are these measuring methods used for?
Both measuring methods are used - also depending on the preference of the artist and of course depending on the local conditions - whenever something true to scale and proportionally exact is to be depicted. This is the case in classical art with drawings that are directly based on the real model, such as figure drawings, portraits, or still lifes. But they can also be helpful for "newer" directions such as Urban Sketching (drawings of architecture and environments).
How do I learn these methods?
Since both methods are relatively simple and quickly explained, it is not difficult to teach yourself these methods. In addition, numerous tutorials can be found online that explain the processes in detail and vividly. However, these tutorials cannot provide feedback on whether you are doing everything correctly, so you should pay close attention to following details.
However, if you want feedback, you should find a teacher who is proficient in these methods and can point out any errors in transferring or properly instruct you. Such teachers can be found in private lessons or workshops, but of course also at schools such as the Academy of Fine Art Germany, which teach these fundamentals to their students right at the beginning of their studies.