Lesson 2: Contour Lines, Texture and Construction

Here we're going to tackle contour lines, a technique that you will carry with you for a long time to come both as a constructional technique to help you better understand how the forms you draw sit in 3D space, and how their surfaces curve and distort, as well as a technique to help convey those concepts to your audience in your final designs and illustrations.

To start, the sausage forms we'll be drawing in this exercise adhere to some very specific characteristics. Specifically, they have ends that are spherical and equal in size, and the midsection maintains a consistent width. You can imagine them as being the combination of two spheres and a bendy cylinder.

While it'll get easier with practice to nail these characteristics consistently, right now we're mainly looking for intent. That is to say, you should be consciously aiming to achieve the characteristics mentioned above, and consciously avoiding the following:

• Ends that are of dramatically different sizes

• Ends that are not spherical (so stretched or flattened)

• Midsections that get narrower or wider

Doing our best to keep to the characteristics explained above, draw a sausage shape on the page. Again, you will probably find this difficult, and it is something you will get better at with practice - so don't expect to be nailing it in the initial homework assignment, it will require additional mileage as part of your warmups.

Draw a line through the center of this form. Try your best to keep it centered, but even if you miss it, that's okay. This line will represent the minor axis of the contour ellipses we're going to add next, though you can think of it like this form's spine.

Even when it's off (as the one in the example image is), it will still tell us a lot about where the line would have been if it were correct, and will help us when aligning our contour lines later, despite its imperfections.

This exercise comes in two flavours - one where we draw complete ellipses going all the way around the sausage form's surface (drawing "through the form" similarly to how we draw through boxes as though we have x-ray vision), and one where we draw only the visible portion of those contour lines, resulting in contour curves. We'll look at contour ellipses first.

The degree of our contour ellipses isn't going to remain the same throughout our sausage. Each contour line represents a cross-sectional slice of the form, and similarly to the cylinders we discussed back in Lesson 1's ellipses section, even before we factor in the bending of the sausage, there will already be a natural trend of the ellipses getting wider the further away from the viewer they are along the length of the sausage. So further = wider is a good basic rule of thumb to follow.

As the sausage bends however, this will also impact the degree of our contour lines, as they will also turn in space. Remember - an ellipse represents a circle in 3D space, and the degree of that ellipse tells us how it is oriented in space, and whether it is turned more towards the viewer (in the case of a wider degree), or more to face across our field of view (in the case of a narrower degree).

This is a lot to think about, so first make sure you're starting with a baseline of your contour lines getting wider the further back they are. If you're not comfortable factoring in the impact of bending right away (during the initial homework assignment), then that's totally okay.

Our work for this exercise (at least in the original homework assignment) is going to be divided up by page, with a page being dedicated either to contour ellipses or contour curves.

When drawing contour curves, all of the same considerations that applied to the contour ellipses apply here as well - the priorities of confidence over accuracy, drawing them a little smaller over a little larger, and the shifting degree along the length of the form.

As noted before, contour curves are not really different from contour ellipses - it's just that we've got our "x-ray vision" turned off, and can only see the visible portion of the contour lines.

This change however, only drawing the visible portion instead of the whole ellipse, does add one issue: it can be difficult at first to achieve the right curvature when only drawing the visible portion of the curve. The surface of this rounded sausage, as we reach the silhouette's edge, turns away from the viewer, and so to convey this the contour line has to accelerate in its curvature as it reaches that edge.

Ellipses do this naturally, and so there we get the accelerating curvature without having to really think about it. That is not so when drawing partial curves, and so it's very easy to end up drawing contour lines that flatten out the form unintentionally.

We can combat this by intentionally overshooting our curves slightly - that is, having them continue along the other side of the sausage instead of stopping right at the edge. Feel free to use this approach when practicing this exercise, especially during the initial homework assignment. When working on it in your warmups, you can pull back on this little by little, although honestly continuing to do this through the entire course is entirely fine.

As the contour line illusion is based around the idea that these lines run along the surface of a given form, it's pretty important that you strive to keep these contour ellipses and curves snugly pinched between the edges of the organic form. This won't always be easy, but there's definitely a visible difference between someone making an attempt to achieve that, and someone for whom it is not a significant priority. Be the former.

As mentioned in the instructions for the exercise, give your ellipses a bit of a shift in their degree as you run through the length of the form.

The reason for this is explained in the little exaggerated red doodle. When you have an object held in front of you and you take three parallel slices of it, your viewing angle for each slice is going to be different. If it's dead center in front of you, you're not going to be able to see any of its face, just its edge. If it's off to the side, you'll see a little more of it.

Now because the size of sausage form is actually quite small, the shift isn't going to be that significant (unless the form itself is bending, which it may well be). All the same, you're not going to end up in a situation where the degrees are all the same.

... At least not unless it's bending backwards in just the perfect amount but we're not going to get into that.

In the instructions for the lesson, I mention that when drawing contour curves, you should try to overshoot them just a little bit. That doesn't mean have them fall outside of the form, but rather that you should let them continue along onto "the other side of the form".

A lot of students find that when they don't do this, even if their contour ellipses are great, they run into this problem where their contour curves end up being too shallow. Learning to accelerate the curvature of the line as it reaches the edge is important, and the overshooting method definitely helps.

Similar to having your ellipses floating around, it's not necessarily easy to nail the alignment of your ellipses each and every time. It is however obvious when a student is making an attempt to achieve that goal, and when a student is clearly not aware of that as a requirement.

Each ellipse should be aligned to your spine line as its minor axis - or in the case that it wasn't centered properly, where that spine line ought to have been. You want it to cut each ellipse into two equal, symmetrical halves down its narrower dimension, just like we did in lesson 1's funnel exercise.

As mentioned in lesson 1, every ellipse you draw for these lessons should apply this technique of drawing through the shape two full times before lifting your pen. This is meant to help you maintain a certain degree of confidence so as to keep things smooth and even.