What are opposing curves?

I have been reading a book about figure drawing and it states that opposing curves are an important concept for drawing figures and other forms in nature. Could anyone explain in a simple way what the opposing curves concept is about?

• Which book were you reading?
– user24
Aug 27, 2018 at 16:06

It is a concept used in creating (drawing, painting, sculpting) organic forms.

Opposing Curves is no more complex an idea than that curves in nature are rarely if ever related to one another as are parentheses ( ), but that rather they are always offset from / or opposed to one another like the curves in the double helix of a strand of DNA. - from CGSociety

The most simple way to explain this is to say that, when drawing, painting or sculpting organic form, we should never use curves that make the form look symmetrical. Beings are not symmetrical. Objects are. So, to achieve organic form, we should not use curves that make being look symmetrical like the objects are. That is why parentheses are used as an example.

() - symmetrical

(( - Opposing Curves - not symmetrical

)) - Opposing Curves - not symmetrical

If you draw a continuous line with opposing curves, you will notice really nice and smooth flow moving down that line.

If we look at the human body (or any organic form), we can see many curves but those curves are made of smaller curves.

Curves also never curve inward ~ curves are always convex, and never concave. Artists, particularly when they are starting out, draw curves which scoop inward, toward the interior of the form - when in fact, form is created by a series of (sometimes minute) convex curves. - from CGSociety

So, to draw an organic form, lets say a human, we should not use Parentheses () curves to depict the form.

Example:

I hope I explained it well.

If you would like to know more, you can read this nicely written article I found (link is NSFW, due to artistic nudity presented): http://www.cgsociety.org/index.php/CGSFeatures/CGSFeatureSpecial/opposing_curves

• I feel that this lacks some of the guidelines on what opposing curves are, such as their purpose in indicating movement, flow, and constructing composition, and focuses a little too much on some aspects like symmetry, which I feel are slightly erroneous. I'm not sure the first Google result for "opposing curves" and "drawing" is necessarily the best reference in this case.
– user24
Aug 27, 2018 at 17:21
• Sadly, I could not provide better answer considering how the question was asked. CGSociety came up as the first result, however, the page itself is really good and it is worth a read. You should definitely share your knowledge. Aug 28, 2018 at 8:49
• I really want to, but I'm unfortunately strapped for time lately! :(
– user24
Aug 28, 2018 at 16:33