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Gurney Journey

This daily weblog by Dinotopia creator James Gurney is for illustrators, plein-air painters, sketchers, comic artists, animators, art students, and writers. You'll find practical studio tips, insights into the making of the Dinotopia books, and first-hand reports from art schools and museums.

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Albino Frogs & Occlusion Shadows

Here’s a study from life of a giant albino bullfrog from an aquarium. The creature was the size of a plucked chicken, and about the same color. He held still for twenty minutes while I did this study.

Albino Frogs & Occlusion ShadowsI drew him in pencil on gray mat board, and then laid a milky wash of opaque watercolor over his whole body, saving the brightest whites for the accents and highlights. When the overall light wash was dry, I added the dark accents in pencil. These include the pupil of the eye and the places where forms push together in the folds and wrinkles.

Lighting specialists in the 3-D CG animation field call these dark places “occlusion shadows.”

Albino Frogs & Occlusion ShadowsWherever two forms touch each other, or a form touches a floor, a dark line or accent results. You can see the effect by pressing your fingers together and looking at the little dark line where they touch. Not much light makes it to that point of contact. You’ll also notice it gets darker in the inside corner of a room where the walls meet.

Computer lighting programs don’t create this dark accent automatically. Until recently it had to be added by hand. But software pioneers have recently made lighting tools that can anticipate when the light will be occluded and such an accent will appear.

As a traditional oil painter, I'm fascinated by such new terminology and visual analysis developed my brother artists in the CG arena. I wonder if one of you who is familiar with 3-D CG lighting might be willing to comment on the challenges presented by occlusion shadows.

Texture in the Halflight

One of the most common mistakes in painting dinosaurs is to make the skin texture equally prominent throughout the form.

In digital work, the appearance of overall equal texture can happen when a bumpy 2-D pattern is mapped equally over a form. The texture is rendered essentially the same way in the shadow as it is in the light, but in a reduced value or tone. Traditional painters are tempted to do the same. That way of doing texture doesn’t look real because it’s not how the eye sees it.

In fact, the textural relief is not equally apparent in the light and shadow. Texture is very difficult to see at all in the shadow region, and it’s only slightly more visible in the fully lit areas. The place to see texture is in the halflight.

Texture in the Halflight
Texture in the HalflightThe halflight is sometimes called the halftone or demi-teinte. This is the area where the form transitions from light into shadow. Astronomers looking at photos of the moon call this region the terminator. It’s the area where the raking light brings out the detail of the craters.

Texture in the HalflightOn this photo of a dinosaur model, I’ve marked the fully-lit areas with an L, the shadow with an S, and the halflight with an H.

Texture in the HalflightHere’s another detail of a painting from Journey to Chandara, showing the halflight in comparison to the light and shadow. Note that the texture in the reflected light (RL) should also be downplayed compared to the halflight. With traditional opaque painting media, you can suggest halflight texture by dragging pigments over bumpy impastos, or in this case, canvas texture.

Texture in the HalflightIn more transparent media you can suggest halflight texture with a drybrush handling. This painting was also done in oil, but the paint is used more thinly.

Happy Thanksgiving. And remember, when you're eating a turkey, you're really eating an "avian dinosaur."

Skybax Model

This painting from the Dinotopia: Journey to Chandara shows Will Denison flying through the mists of Waterfall City on his giant pterosaur Cirrus. I wanted to give the painting a feeling of lightness and airiness, so I stuck to pale tones in the distance, and a warm palette of color overall. It’s another example of the weird principle of reverse atmospheric perspective brought on by edge lighting in a moisture laden environment.

Skybax Model
To figure out how the edge lighting would appear on the architecture and the flying figures, I put my maquettes to work in real sunlight. Here’s a little model of Will flying on Cirrus that I've used many times before. The pterosaur model is made from a variety of materials: Sculpey, wood, pipe cleaners, and cardboard. It has poseable wings, which are made from a pair of old stockings that have been painted with latex to give them a membranous surface.

Skybax Model
With the model set up in the real sunlight you can see clearly how the top side of the near wing picks up the cool of the sky, while the far wing is warm from the transmitted light shining through it.

Studio Lighting: Part III: Edge Lighting

A couple of posts ago the topic was lighting equipment and the basic relationship of the two basic sources of light: key and fill. The third light source, entirely optional, comes from behind.

Often called an edge light, it lights up the fringes of the form, separating it from the background. It’s also called a “rim” or “kicker” in the TV business, and it usually requires a source that’s stronger than either of the others. The form has more snap if the edge light doesn’t overlap too much with the key light, leaving the dark turning of the form (sometimes called the “core” or the “hump” of the shadow) intact.

Studio Lighting: Part III: Edge Lighting
This oil study from the model has the key and rim lights placed just far enough apart so that you can see the core of the shadow on the forehead.

If you want to introduce an edge light source, it should be a different color from the key. By applying contrasting gels to the key and edge lights, you can generate some interesting effects with skin tones. On this portrait I used a warm key light and a cool edge light.

Studio Lighting: Part III: Edge Lighting
On a future post I’ll suggest some painting methods to make it possible to do these quick oil studies in the standard 20 or 30 minute poses that you get in most sketch groups.

Studio Lighting II: Key and Fill

Before there was light, utter darkness moved upon the face of the world.

That might sound sort of biblical, but it’s the best way to think about lighting. Everything starts out as black as night until the light comes into the scene.

It’s easy enough to see how the main light source illuminates the form. But it would be a mistake to think of the shadow side as the absence of light. There’s light filling the shadow, too, but it’s just another kind of light from a weaker source.

Studio Lighting II: Key and FillHere’s an example. I’m posing here with a kaffiyeh as a reference for a painting of Arthur Denison on page 119 of Dinotopia: Journey to Chandara. The main light, from the baby spot, is coming from above and to the right. The shadow side is getting weak, cool light coming from the skylight and the north window at left. The shadow side of the form wouldn’t be anywhere near black unless I was in a windowless room with black velvet wallpaper.

Studio Lighting II: Key and FillHere’s an oil study of a model lit from a low light coming from the left. Photographers call this main light the “key” light. The shadow is getting greenish light bouncing back from a cloth that was behind the model. This light that enters the shadow is called the “fill” light. In TV and movie lighting, a second, weaker electric light usually provides the fill light. But most often we painters use natural reflected light for the fill.

Studio Lighting II: Key and FillThis head in profile has the key light coming from the left, shining directly in the face of the model. The fill light is much weaker, making an extreme “lighting ratio” of key to fill light. The greater the ratio, the more low-key or dramatic the form will appear.

Note that I placed the light in the direction of the subject’s gaze. I think we all have a basic instinct to look toward the light of a window or a doorway, and to me it is satisfying in some deep way to look at a face that is oriented toward the light. Next time you’re sitting absent-mindedly in a dark room, take note of the fact that you instinctively rest your gaze on the lightest area of the scene.

Studio Lighting II: Key and FillOn this half-hour oil sketch from life, I used the baby spot with an orange gel for the key light coming from the right. I set up a second fill light with a contrasting blue-green gel. The brightness of the fill light almost equals the key light, leading to a close or “high key” lighting ratio. It looks unnatural and weird simply because such a relationship could not happen under natural conditions.

Only a few places on the face are not touched by either the key or fill lights: the side of the nose, the edge of the eye, the lower cheek, and the neck. As a result those areas are quite a bit darker.

Check back in a couple of days for the last in the studio lighting series: edge lighting.

Studio Lighting, Part 1: Equipment

When you’re setting up a model to paint from life, it helps to use a strong light source, placed well away from the model. If the light is set too close, you get a variation in light intensity: a hotspot on the top half of the figure, and the feet lit dimly from a different angle. Painting is hard enough! We don’t need obstacles like that.

The standard clamp-on reflector lights from the hardware store don’t cut it. Their light is just too weak. But they’re used all the time, even in art schools, which should know better.

Studio Lighting, Part 1: Equipment
It’s well worth investing in a professional light designed for use on the stage or movie set. Here’s a Mole Richardson Baby spotlight, a good solid workhorse for a small to medium-sized studio. It attaches to an adjustable tripod that lets you lift the light up to 14 feet in the air.

It will easily take a 600 watt bulb (about $30 each), which shines through a fresnel lens. If you want a lower intensity, you can use a smaller bulb. You can place the baby spot 20 feet away from a model and twirl a knob to zoom in the light just where you want it.

The baby spot also has adjustable “barn doors” to control how much light spills to the sides, and a rack for hanging the plastic gels or color filters in front of the light. The gels are made to withstand heat, but with a really hot light, you might want to clip the gels to the barn doors, farther from the heat of the bulb. In the photo I’m putting a blue gel in the rack.

It’s shining on a plaster cast of Abe Lincoln and a plastic chrome hemisphere. I mentioned the mirror ball on a previous post. It’s useful for recording the source and character of the light influences in a given scene.

Art supply catalogs don’t usually carry these lights, instead stocking wimpier equipment that isn’t worth investing in. I don’t want to sound like I’m giving anyone a commercial plug, so I’ll leave it to you to hunt down sources and brands. Try googling “stage or theater lighting supply” or search Ebay. The retail stores also sell C-stands, mentioned in an earlier post.

Studio Lighting, Part 1: Equipment
This 30-minute oil study of a model was painted using the baby spot set right up behind and above me for a fairly simple frontal lighting.

In tomorrow's post, (Studio Lighting II: Key, Fill and Edge) we'll take a look at strategies for placing the lights.

Contre-Jour Lighting

Contre-jour lighting is a type of backlighting where you place the subject right in front of a bright, sunny sky. In French the phrase literally means “against the day,” a poetic way to express this mysterious and powerful effect.

The term is still in common use among photographers. But cameras can’t deliver this effect as powerfully as painters can, because cameras are unable to respond to a wide enough range of intensities, and the silhouettes tend to go to black.

Contre-Jour LightingArtists of the 19th Century did wonders with contre jour. You’ll find it with Royal Academicians like Atkinson Grimshaw (upper left), Barbizon painters like Constant Troyon (the other images here), and American landscapists like Frederick Church.

Contre-Jour Lighting
Troyon’s student Leon Belly used this effect to capture a feeling of dazzling, intoxicating illumination in several of his Orientalist paintings, like this one of water buffalo in a desert oasis. I learned about contre-jour lighting from art historian Kristian Davies, who discusses it in his brilliant book The Orientalists (Laynfaroh, 2005).

Contre-Jour Lighting
When a form is placed contre-jour, it goes into silhouette. The colors weaken. Shadows stretch forward. Details disappear as the glare of the light spills over the edges of the form. The sun itself often shines from inside the frame of the picture, making the viewer’s eyes squint involuntarily.

Contre-Jour Lighting
I’ve been fascinated by the idea of contre-jour since starting work on Dinotopia: Journey to Chandara, and it crops up in quite a few of the paintings in the new book, like the one above, where Arthur and Bix are approaching the Imperial Palace.

Today I visit Rhode Island School of Design. Stay tuned in a couple of days for the report.

Transmitted Light

When sunlight travels through a semi-transparent material, the light becomes richly colored. Light that just bounces off the surface is fairly dull by comparison.

This “stained-glass-window effect" is called transmitted light, and you often see it when the sun shines through the green or yellow leaves of a tree. You might also see transmitted light when the sun backlights colored balloons, a sailboat’s spinnaker, or a translucent nylon awning.

Transmitted LightThis on-the-spot oil painting of a skunk cabbage plant is a study of transmitted light. The bright yellow-green area is much more intense than the other greens.

Here’s the picture again, with numbers superimposed in each area of the foliage to analyze what’s going on with the light and color:

Transmitted Light
1. Transmitted light, with intense chroma or saturation in the yellow-green range.
2. The leaf in shadow, facing downward. This is the darkest green, and would be even darker if it wasn't picking up reflected light from the adjacent leaf seen edge-on.
3. The leaf in shadow, facing upward. These ‘up-facing planes’ are blue-green, because they are picking up the blue light from the sky.
4. Sunlight reflecting off the top surface of the leaf. This is the highest tone or value, and the most textural, especially where it transitions to shadow. But the chroma is not very intense, because most of the light bounces off the waxy cuticle of the leaf.

When you are painting a faraway tree backlit by sunlight, it’s good to keep in mind these four conditions: transmitted, downfacing shadow, upfacing shadow and sunlit. These colors, visible in the skunk cabbage up close on a micro scale, are present here, too, mixed together like tiny pixels even if you can’t really see the component leaves.

Transmitted Light
The distant foliage is a composite of all four color elements, blended with the atmospheric effects. As you can see in this faraway view of autumn maples, there are more leaves shining with transmitted light at the lower left margin of the tree. The leaves in the central area are darker and duller because they’re lit by the cool skylight.
Albino Frogs & Occlusion ShadowsTexture in the HalflightSkybax ModelStudio Lighting: Part III: Edge LightingStudio Lighting II: Key and FillStudio Lighting, Part 1: EquipmentContre-Jour LightingTransmitted Light

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