A layout sketch is the process of faintly outlining the key elements of an image on to paper (or canvas). The aim should be to get each component the correct size and in the right position before moving forward. However, this first stage is where most amateur artworks go wrong!
In a portrait for example, the layout sketch would merely ensure that the outline of the eyes (nose, mouth, etc) are the precise shape, correct size, accurately aligned and the right distance apart. The layout sketch requires no further detail, but get this wrong, and your artwork will be doomed to failure, no matter how good your painting or drawing technique is.
It is possible with a great deal of practise and care, to complete a layout sketch by eye alone, but is that how professional artists work? No they don’t! Time is money and professional artists use techniques and tools to get precise layout work done quickly.
Here are the most common tools and techniques for working from a photograph.
The simplest tool is use of a pencil as a ruler and protractor. For example, when drawing a face, the pencil can be used to measure the relative size of an eye, the distance between the ear lobe and the corner of an eye, or the angle of the nose. This works best when copying from a large photograph, and reproducing an image at the same size.
The technique is simple: lay the pencil flat on the photograph. Place the point of the pencil where you want to measure from, and grasp the other end of the pencil at the exact point you wish to measure to. Without changing your grip, move the pencil to the paper and make a mark on the paper at the tip and point of your grasp.
Similarly, angles can be duplicated by laying the pencil on the photograph, say a roof line in a landscape, and carefully moving the pencil to the paper while retaining that angle. An easier method is to place you reference photo over your paper, so that the pencil can be rolled from one surface to the other without altering its angle significantly.
A slightly easier method is to use a ruler, and take absolute measurements. If you need to re-scale an image, the use of a ruler is preferable. For example, when scaling up to twice the size, you simply double the measurement (etc). But, this technique has become outdated.
Alternatively, it is possible to buy dividers that achieve the same measuring effect. Some even have a limited re-scaling function.
Most people now have access to a PC with peripherals, so it is easier to scan and re-print a photograph at the same size you want to draw or painting, rather than re-scale as you go.
The use of a pencil (or anything else) as a ruler is best employed for checking minor detail dimensions and angles.
Another slightly outdated but effective method of laying-out is the grid. Briefly, you need to draw a grid over the reference image, and a grid on your paper. The layout is achieved by separately copying the contents of each box of the grid. In effect, your layout will comprise lots of tiny drawings that all fit together to make the whole.
Using a grid limits the potential for error, and the smaller your grid boxes, the more accurate your copy will be. If your grid is say 1cm squares, then your layout lines can never be inaccurate by more than 1cm (unless your grid is inaccurate, or you draw something in the wrong square), but the chances are your sketch will be pretty close to millimetre perfect.
You can use grids of different sizes for the reference photograph and the artwork. In this way, re-scaling (if you need to) is easy. For example, to double the size of your drawing, use a 1cm grid on the photo, and a 2cm grid on the drawing paper. However, for the system to work, both parts must have the same number of grid boxes.
Grids take a good deal of effort to use. The other down side is that the reference photograph must be expendable (you need to be able to draw lines all over it), and you need to remove the grid lines on your art paper when you have finished the layout. Grids are good for oil paintings, since they can be painted over.
Many professional artists use tracing paper. It is a really accurate way of completing a layout. I recently read an instructional article on the use of tracing paper, published on a major UK artist site. My recommended method of use is very different.
The first thing is to lay the tracing paper over the image to be copied, and mark its position. This is so that you can place the tracing paper over the image time and time again, and always in exactly the same place.
Although tracing paper is very transparent, it can be hard to see detail in darker tones. The best way to use it is with back illumination; do your tracing on against a windowpane (in the day time!), rather than on a desk or table.
Draw carefully around the key elements with a sharp pencil (step 1). Reverse the tracing paper and draw accurately over your pencil lines, to create a mirror image on the backside (step 2). Use a sharp soft pencil for this, and remember that an outline with be transferred to whatever your tracing paper is resting on (so use some scrap paper). Now place the tracing paper right side up on your art paper. Mark its position, so you can put it back in exactly the same place if you need to. Draw over your pencil lines again to transfer the image (step 3). At no point should you scribble. Use the minimum pressure on your pencil marks; the aim is to transfer a light (temporary) pencil mark, not engrave an outline into your art paper.
It takes some time, but you should end up with faint, but very accurate layout lines. Obviously, you cannot re-scale an image using tracing paper. Tracing paper works best on a smooth surface. You may struggle to achieve a transfer on watercolour paper, and toothed pastel papers, so aim to transfer the minimum detail you need for a layout.
When working with darker papers, a white pencil at step 2 gives better results. A white pencil also often gives better results with coloured pastel papers.
Tracedown paper is a form of carbon paper for artists. I have never personally used it, but it works like tracing paper with steps 1 and 3 being performed simultaneously, and step 2 omitted completely. Briefly, you place the transfer down paper on your art paper, the photograph on top, and you draw around the key elements directly on to the photo. The pressure of your pencil makes a faint line on your art paper.
As with tracing paper, re-scaling is impossible, and I imagine the reference photo takes a bit of a battering.
There are a number of specialist projectors that can be purchased. Briefly, this tool projects an image on to art paper, and allows layout lines to be drawn directly on to the paper (or canvas), using the projected image as a guide. They are fast, and designed to accommodate re-scaling, but they are expensive and aimed at professional artists. The projector is a modern take on a system of layout transfer used by the old Masters.
Finally: trying to do everything by eye alone is foolish and unprofessional. Get an accurate layout down using any technique or device available to you.