Wednesday, April 30, 2008

Art By Committee: Blue Robe Results

The other day someone asked me, “Is that sketch game on Wednesdays just for professionals? Are they all your friends? Does someone have to be a member of an exclusive club to participate?"

A lot of sketch games are set up that way, but not this one. Everyone is eligible; you don’t have to join a club; and I post every submission, not just the cream of the crop. It just happens to be a great crop! Many of the contributors are professionals, but a lot are students or people who do art just for fun.
For those new to Art By Committee, your mission is to illustrate an authentic excerpt from a science fiction novel. This week’s quote brought out everyone’s best, as you can see below:
Dave Harshberger

Jenn Morris

Rob Hummer

Michelle L.

Roberta Baird
Jen Zeller

Art Keegan

Tyler Davis

Jess Ellwood

Rose Dawson

Susan Adsett

And, from the original sketchbook, the one by me, my wife Jeanette, and James Warhola.

Now, here’s next week’s challenge: “...selection, so that evolution had leaped. Somehow all that other people noticed about her particular subspecies was its supposed simian characteristic.”

Please scale your JPG to around 700 pixels across. Title it with your name, send it to: jgurneyart(at), subject line ABC, and let me know in your email if you want me to link to your blog or website. Please have your entries in by next Tuesday at noon.

Previous Art By Committees, Link.

Tomorrow: Last Dino Art Workshop

Tuesday, April 29, 2008

Edge Induction

It was twilight in Tannersville, New York. A light rain had been coming down steadily all day. I set up my easel under a store awning because I stupidly forgot an umbrella. The aroma of French onion soup beckoned from the restaurant across the street.

The sun must have set by now because the light was failing. The light from the sky seemed to have bluish cast in contrast to the warm lights that were coming on. But I wasn't sure. I could practically feel the cones in my eyes shutting down. Honestly I could hardly see what colors I was mixing on the palette, because I forgot a flashlight, too.

As I studied the scene I realized that I could easily see the sharply defined contours of the utility pole and the roofline against the bright sky. But I couldn’t make out the clapboards or the signs; in fact I really couldn’t see the windows or doors at all—except on the bright white building in the center of the picture. So I tried to paint the scene as I saw it: blurry and tentative.

This illustrates a principle called “edge induction.” When a subject is poorly lit or in shadow, some of the edges will be below the threshold where our eyes can discern a contour. A camera might be able to pick up all the edges in these dim zones, but not the human eye.

It's not just a matter of what the rods and cones can respond to. What happens without you knowing it is that your brain takes over where your eyes leave off. In dim conditions your visual cortex starts interpolating or inventing contours based on the few edges that you truly can see and on your prior knowledge of how things should look.

The brain wants to confirm the contours first, and then it quickly fills them in with textures, tones, and colors—almost like a coloring book. This happens instantly at an unconscious level, as was demonstrated in a study published last summer by researchers at Vanderbilt University.

The visual cortex is always busy constructing a detailed fabrication of the world, whether it has all the information or not, and it tricks you into thinking you’re seeing edges that really aren’t visible.

Painters shouldn’t seek out edges that aren’t there; in fact poetry often springs from deliberately placing edges into obscurity, as Meissonier did in this portrait of Dumas.

Let edges and details go out of focus in sub-threshold or shadow areas, as Gerome did with the shadow-side eye in this portrait of a peasant. If you like a painterly handling, here’s the place to use sketchy, soft brushstrokes. It’s perfectly OK to deny the viewer the chance to scrutinize the details too much.

For more about that Vanderbilt University study and the phenomenon of edge induction, link.
The last three images came from Art Renewal Center, link.

Tomorrow is the Art by Committee sketch challenge. Please get your sketches in by Tuesday at 6:00 pm. Eastern Time, USA. To read about the challenge, link, and then scroll down.

Monday, April 28, 2008

Cockpit View

I suppose the world has changed a bit since the day twelve years ago when I sketched this inflight view of an open airline cockpit. It wasn’t too long ago that taxi cabs didn’t have partitions and that you could walk right into an elementary school—or the nation’s capitol.

Sunday, April 27, 2008

Sky Blue

Most people know why the sky is blue: small particles in the atmosphere scatter the shorter (blue and violet) wavelengths from the white sunlight so that the blue light bounces around in all directions, covering the black void of space with a veil of sapphire.

As artists, we need to know a little more than that. How does the sky color change as we look in different directions? Where is the blue darkest or most chromatically saturated?

Here are two photos that were both taken at 4:10 in the afternoon of April 12 in Germantown, New York. The one on the left was taken facing the sun, and the one on the right was taken seconds later facing away from the sun.

The clouds are completely different. Near the sun, clouds have dark centers and light edges. With the sun shining directly on them at right, they are lightest at the tops or centers and they get darker at the sides and bases. Smaller clouds are not as white because they have a lesser mass of vapor to reflect back the light.

The color of the sky is different, too. Around the sun is a region of warm glare which weakens the chroma of the blue, making it more of a dull grey-green. Looking away from the sun, the blue is more saturated, tending a bit more toward violet.

How do we know the camera isn’t deceiving us? Is there another way to check these observations?

I went to my local hardware store and picked up a bunch of blue paint swatches. Here’s how the sky looks compared to the paint swatches while facing away from the sun. One of the blue swatches (A) is a close match to the adjacent area of the sky.

I wanted to photograph the swatches while facing toward the sun, but I had a problem. There was no way to angle them so that the sun could shine directly on them. So I set up a mirror on the windshield of my car to bounce the light back onto the swatches.

But we can’t trust this comparison, because those color swatches are lit by the warm light bouncing up from the ground and from my t-shirt. That’s why the swatches look a little warmer than they should.

Here’s another experiment to demonstrate how the sky gets lighter near the sun. I took a single paint swatch, cut it in half, and taped the symmetrical halves on a mirror to make a device that we can call a "cyanometer." None of the swatches matches the sky exactly. The hue and chroma are different, but the values come close in a couple places.

Clearly the value of the sky darkens as we shift our gaze horizontally away from the sun. The left arrow, nearer the sun, matches the value of the lightest swatch, while the right arrow, just a little bit farther from the sun, matches a swatch that’s two steps darker. The mirror is reflecting another section of the sky, which also gets darker from left to right.

The sky color shifts in value from zenith to horizon, too, as we can see when the cyanometer is arrayed vertically. At (A) there’s a close match of value between the darkest swatch and the distant sky, even though the chroma is different. Higher in the sky at (B), the same swatch looks much lighter than the sky surrounding it.

The mirror reflection shows an instant comparison of what’s going on behind us in a region nearer the sun. This area of the sky is much brighter in value, as well as being duller in chroma, confirming the first pair of photos in this post. The swatches at (C) and (D) show us that the sky in the region of the sun stays about the same value as it goes up from the horizon, because the increasing solar glare offsets the effect of lightening near the horizon.

Let’s draw some general conclusions from these observations.

  • First, there are two separate but overlapping systems of color gradations in a daytime sky. One system, "solar glare," is governed by the proximity to the sun. The other, "horizon glow," depends on the angle above the horizon.
  • In each of these two systems the sky color gradates in value, hue, and chroma. These two systems interact with each other so that that every patch of sky gradates in two different directions at once. This means that the painter in opaque colors needs to mix at least four separate starting colors to paint any given segment of clear blue sky.
  • As we move from the zenith to the horizon, the sky generally tends to get lighter, because we’re looking through more atmosphere. A poet might say we’re peering through more veils drawn across the void of heaven. Near the horizon, depending on the time of day and the direction of view, the sky color can range from a pale cerulean to a warm grey to a dull orange, but usually it’s a whitening.
  • As we approach the sun, the color gets lighter and warmer because a great volume of white light is scattered at shallow angles by large particles in the atmosphere. You can see this best by standing near the edge of the shadow of a building with the sun just hidden behind the roofline. A weaker but noticeable lightening also occurs at the “antisolar point,” 180 degrees opposite the sun.
  • The point of the darkest, deepest blue, which I call the “well of the sky,” is at the zenith only at sunset and sunrise. To be precise, the well of the sky is actually 95 degrees away from the setting sun across the top of the sky. At other times in the day, the well of the sky is about 65 degrees away from the sun.

Notes and recommended reading

Why is the sky blue? Link.
Some ideas in this post are based on Light and Color in the Atmosphere by M. Minnaert (1954) in Dover edition, link
Minnaert and scientists as early as Humboldt built instruments
that they called cyanometers for observing sky colors, but they were of a different design, link.
Photos were taken without polarizing filters.

Saturday, April 26, 2008

Fresh Out of Mummies

Maybe it’s just as well that some traditional pigments are no longer made from their original sources.

Sepia brown was once made from the ink sac of the cuttlefish. There’s a chemical substitute now, thank goodness for the little cephalopods.

Indian yellow *allegedly came from the concentrated urine of cows fed on mango leaves. It was outlawed in 1908, because it was hard on the cows.

And mummy brown derived from the ground-up remains of Egyptian mummies. They stopped in the twentieth century when the supply of mummies ran out.

*More on the Indian yellow mystery, link and link.
Tomorrow: Sky Blue

Friday, April 25, 2008

Vignetting: Part 3

Let’s conclude our look at the ten kinds of vignette compositions.

The Sketchy Edge Vignette
A painting can dissolve into sketchy lines, giving us the feeling of an informal sketchbook page. Dutch illustrator Rien Poortvliet often used a sepia penline to establish his vignette illustrations, in this case from the book “In My Grandfather’s House.”

And Dean Cornwell lets his preliminary brush-drawn lines hang out, finishing the figures above the sketchy edge.

The Cutback Vignette

The silhouette shapes of JC Leyendecker’s figures are painted first on a toned canvas. Then he cuts back with white paint, using long strokes and a slippery medium. This is just a study, but it shows his method in action.

This more finished cover is done in the same way, leaving a few spaces between strokes where the toned canvas can be seen.

The Wraparound Vignette
A wraparound vignette sets up the detail around the outside edge of the design, leaving the white of the page open for type. Jon Whitcomb establishes a feeling of firelight and moonlight.

The blacksmith shop of Volcaneum in the first Dinotopia book was conceived in the same way, with the white space used for text.

Breakaway VignetteIn this last vignette strategy, the form pops out of the rectangular panel. It's perfect for explosive action, but it calls attention to itself, so it should be used sparingly. This one appears in Dinotopia: The World Beneath.

I used a similar idea in an unused sketch for National Geographic, where I wanted to convey the sense of speed and danger of a chariot race.

To recap, the ten types of vignettes are soft blur, torn paper, fadeaway, form-link, real white, spillover, sketchy edge, cutback, wraparound, and breakaway.

Read the whole series:
Vignetting, Part 1
Vignetting, Part 2
Vignetting, Part 3
More on vignetting in my book: Imaginative Realism: How to Paint What Doesn't Exist

Thanks to the following this week:
John Flesk, link.

Roger Reed of Illustration House, link.
Leif Peng’s Flickr sets, link.
Jim Vadeboncoeur’s illustrated books, link.
100 Years of Illustration, link.
Armando Cabrera, link.
Illustration Art, link.

Tomorrow: Fresh Out of Mummies

Thursday, April 24, 2008

Dino Art Tips 4: Environment

To paint a convincing scene of dinosaur life, you need to think about the setting as much as the dinosaur itself. In this fourth installment of my paleoart workshop, here are five tips to help you paint realistic environments for your creatures. To see the full dino art workshop, check out the current issue of ImagineFX magazine, which should still be on the newsstands in the U.S.A.

Avoid the “dry lake bed” look
I’m guilty of this one as much as anyone else. We’re all tempted to stage dinosaur scenes on featureless dry lake beds. Why? Because it’s easier than dealing with foliage. But nature rarely looks like that. Usually every available piece of ground is covered with plant life. Unless you’re actually setting the scene on a flat landscape, make the terrain uneven. Toss in a fallen log or some boulders. Give the dinosaur something to step over or to squeeze underneath. By giving your dinosaur something in the scene to interact with, you can convey tremendous realism.

Grab environment photos
Whenever you travel to places with Mesozoic plant types, take photos for future reference. Florida has palmettos and cypress swamps that look a lot like what you would have seen 100 million years ago. In other locales you can find ginkgo, redwoods, low ferns, tree ferns, and Araucaria. Take a variety of angles: closeups of branches, tree bases, rotting trunks, and swampy edges.

Add dino damage
Large animals in Africa are hard on plants, and dinosaurs would be no different. Look at photos of plants in Africa, where animals break off low branches, trample small plants, rub against the bark, or nip off all but the highest leaves. If you add dino damage on the plants and trees, you’ll add a level of storytelling that will add naturalism to the whole scene.

Overlap the foreground
Overlap parts of the dinosaur’s figure with foreground detail. This almost always happens in real life. The detail might be a branch, a rock, a clump of ferns, or another dinosaur. Don’t show the whole pose in crisp detail. Throw parts of it out of focus. If the foreground element is close to the viewer, blur it a bit.

Add dappled light
If your scene is set underneath tall trees, most of the subject will be in shadow, with spots of dappled light filtering down from the canopy. You can use this effect to your artistic advantage by featuring the center of interest in strong light, and disguising the less important parts of the pose with dappled illumination. Remember that the size and blurriness of the dots of light increases as the ray of light travels farther from the source of the cast shadow.
Previous dino art workshop posts: Part 1, Part 2, Part 3
Previous GJ post on dappled light, link.
ImagineFX Magazine, link.
Cassowary image from Picasaweb, link.
Elephant damage, link.

Tomorrow: The last installment on vignetting

Wednesday, April 23, 2008

Art By Committee: “Tinted Orange”

On Wednesdays we've been playing a group sketch game called "Art By Committee." I share an actual excerpt from a science fiction novel and you come up with a sketch to illustrate it.

This week our quote was: “….protested. He too was tinted orange with anticipation.” I know, it’s a little weird, but I had a feeling you would come up with really creative solutions--and you did! Nice work, everybody.

At the end of the post is next week’s quote, so if you missed this one, scroll down and put on your thinking caps for next week.

Arthur Keegan

Rob Hummer

Susan Adsett

Jen Zeller

Gally Mathias

And the group effort from the original Committee sketchbook.

Here’s the challenge for next week, and this one should spark a lot of fun ideas. Please have your sketches in to me at jgurneyart (at) by noon this coming Tuesday. Title your JPG file with your name, let me know your preferred link, and have fun!

Tomorrow: Five More Dino Art Tips