How Shading a Line Drawing Reminded Me of Graphics Algorithms

Someone I know drew this cute frontal portrait:


They didn’t know how to shade it, so they asked me to do so.  I used Procreate for iPad and a stylus.  A half hour later:


This got me thinking about graphics algorithms!  (I loved my college course in graphics algorithms, back in the day.  We used OpenGL and C++ to do some pretty neat stuff.  The projects were challenging but rewarding.)

I’m thinking that it shouldn’t be too difficult to write an algorithm that takes an unshaded frontal portrait and uses some heuristics about relative angles and lengths to transform it into a believable three-dimensional face.  Then, it can generate a light source from a prespecified location and “shade” the face automatically.  I don’t know if this has been done, but it seems fairly straightforward, so it probably has!

How to Draw Trees, Hair, and Other Very Complex Things

A large tree can hold millions of leaves and at least thousands of branches (if you count the twigs).  A human head can have more than a hundred thousand hairs on it.  You’d be a fool for trying to draw a tree or human hair photorealistically, right?  Well, yes and no.

A couple years ago, inspired by the majestic trees I saw while hiking in Yosemite National Park,  I tried to draw a photorealistic tree.  This is the result:

Unfinished pencil drawing of a Jeffrey pine seen near Glacier Point, Yosemite National Park
Unfinished pencil drawing (4B graphite on Bristol board) of a Jeffrey pine seen near Glacier Point, Yosemite National Park. Circa April, 2012.

Yep, I gave up.  Although I was still learning to draw at the time and this was good practice for me, it was too painful to continue!  In retrospect, I was going about it the wrong way.

I was trying to draw every single detail as I saw it.  How painful is that?!  Let’s just say that I’ll never do that again.

You can draw trees or hair or anything else photorealistically in a freehand way (instead of tracing)*, but you’d be foolish to try to draw complex details exactly as you see them instead of drawing the general pattern that you see.

Drawing the general pattern is the key to drawing hair and foliage photorealistically without driving yourself nuts.

Don’t get me wrong:  it’s not easy to draw anything that has a lot of detail.  Photorealistic pieces are very time-intensive.  For example, Paul Lung, an artist who uses a mechanical pencil to create photorealistic drawings of cats, supposedly takes 40-60 hours per piece.

However, it simplifies things and speeds you up, if, instead of drawing exactly what you see when you look at something extremely complex, you draw the general pattern.  The result will still be photorealistic.  (Note:  this might not work for portraits, because our brains are designed to pick up on very subtle facial differences.  This is one reason that drawing portraits is harder than drawing other things.)

If you simply want to give the impression of something complex, like a tree, hair, or fur, then you should give only as much detail as necessary and leave the rest up to the viewer’s imagination.  Unless your aim is photorealism, you should stop when you’ve suggested enough to the viewer that they can identify your subject.  As Betty Edwards says, you shouldn’t overdraw.

Respect for negative space is important when drawing trees, as is remembering a few key heuristics:

1. Branches should get thinner as they extend farther from the trunk.

2. Any branch must be thinner than the branch or trunk it’s growing from.  (Otherwise, it will not look realistic).

3. Vary hue, value (very important), and chroma when painting leaves.

4. Depending on the type of tree you’re drawing, branches will grow out at different angles at different heights along the trunk.  Usually, though, this angle is more acute higher up and closer to horizontal lower down.  Don’t forget to draw in branches that face toward and away from the viewer!

5. If painting in watercolor, consider using a natural sponge to quickly paint foliage.

Here’s a quick sketch I made (with a Pentel Pocket ink brush pen and black ink) of a pine tree at a nearby park, back in January:


Here are a couple imaginary trees I sketched by following the above heuristics:



Here’s a digital painting of oak trees (initially posted here):


When drawing human hair, focus on large masses of color and try not to get bogged down by drawing too many individual hairs.  Keep the outer edges of hair (where it meets the air) somewhat blurry, except where hair meets the face, which can be drawn in some detail.

After some practice, it all becomes easier and more natural!  Artistic skill (or any skill, really) is all about quantity of practice!

*Many photorealists avoid drawing freehand and instead use grids or projection techniques to trivialize the transfer of correct perspective.  Personally, I’ve always drawn freehand because I enjoy the challenge!

Drawing a Devil’s Claw in Charcoal and Graphite

Drawing of a devil’s claw in charcoal and graphite on 11″ x 14″ Bristol board

“What is that?!”

That’s the usual reaction I get to the dried fruit of the Proboscidea (plant, not the order of megafauna with trunks).  It’s also known as the unicorn plant.

Here’s the same drawing in different lighting:

Drawing of a devil's claw seed pod in charcoal and graphite on 11" x 14" Bristol board
Drawing of a devil’s claw in charcoal and graphite on 11″ x 14″ Bristol board

This is the actual devil’s claw:




The devil’s claw/unicorn plant is considered a holdover from the Ice Age, back when giants last roamed the Americas.  The dried fruit has large burs with which it used to hitch rides on the fur of Ice Age megafauna.  It can also hitch a ride on your shoe or, if you’re not careful, inflict a pretty bad puncture wound.

My particular seed pod was a gift from a friend who found it at a farmers’ market in Wisconsin.  In return, I gave him my drawing.

The drawing was one of my first charcoals.  It was difficult to use charcoal on a smooth surface! Bristol board, being very smooth, is best used for pen, marker, and fine pencil drawings.  Also, I had some trouble using charcoal with graphite.  Charcoal has a matte finish, while graphite is glossy, so it can be tricky to use them in combination.  Many people think that charcoal and graphite shouldn’t be used together at all.  However, this hyper-realist disagrees.  (His book is excellent, by the way.  If you’re at all interested in realistic representational drawings in graphite and charcoal, you should check it out.)

Since then, I’ve used Strathmore 400 Series drawing paper.  Although commonly available in the US, it took me a while to discover that it’s excellent for charcoal, pencil, or other dry media, and is pretty much the consensus paper to use for practice drawings.  It’s acid-free but not archival-quality; according to Hillberry, it might yellow over time.  He recommends using 100% rag paper for final drawings. Dedicated charcoal paper exists, and some artists use pastel paper, but I haven’t yet used either.