Cross contour lines are drawn lines which travel, as the name suggests, across the form.
Cross contours may be horizontal or vertical, as on the right side of the example, or both.
Often, in more complex forms, cross-contours will be drawn at varying angles.
In this rather lumpy example, the grid of cross-contours looks a bit like the gridlines on a globe or a diagram of a black hole in space.
Often cross-contours look like the contour lines on a map of rough terrain – they help us visualize the topography of a surface.
Usually, we don’t draw them this mechanically, but use the understanding of cross-contours to help us describe the form with more subtle line or shading.
They help us understand the three-dimensional form and describe it on a two-dimensional surface.
Contours wrap around a form and obey linear perspective.
In this example, the basic contour drawing is developed with some hints of cross-contour to suggest the form.
The brain needs surprisingly little information to create a three-dimensional image from a simple drawing.
Cross contours don’t have to be obvious – they just indicate the direction and the imagination fills in the rest of the information.
Cross-contours don’t need to be mechanical unless you are drawing a topographic map.
You can use your understanding of the cross contour to create expressive marks which add energy to the drawing.
This interpretation of the subject using contour and cross-contour is more free and expressive, using a relaxed line but still paying attention to the observed form.
Cross-contours are often used when hatching.
The cross contour lines may be carried all the way around the form, or used in small sections, curved, or straight, as in this example.
The angle of the hatching as it moves around the form changes according to perspective.
Even if you are using shading and attempting to create a smooth surface, being aware of the flow of cross-contours as you draw can help you create a shaded surface that follows and enhances the three-dimensional form, rather than fighting against it.