Dappled Light

Light coming through trees results in the spotted light we know as dappled light. The painting below is by Ivan Shishkin.


The circular spots of light shining on the ground vary in size depending on how high the canopy is above the ground. A high tree canopy leads to larger circles with softer edges. Below, in this early Albert Bierstadt painting called “Sunlight and Shadow” the effects of dappled light are worked out extremely convincingly.


When bundles of light pass through small spaces between the leaves, each of those spaces act like a pinhole camera. The parcels of light are essentially like conical shapes of illumination radiating from each pinhole in the foliage.


The circles of light touching the ground are actually projections of the disk of the sun. In fact on days with a partial eclipse of the sun, the circles of light will appear as half circles. In the 8x10 inch oil study above, the circles of light on the roof of the shed are about a foot in diameter.

When each cone of light intersects a sloping surface like a wall, it results in an elliptical shape. On a vertical surface parallel to the picture plane, the long axis of that ellipse will always angle back toward the source of the light.

In the detail above from Dinotopia: Journey to Chandara, the light is coming from the right. The circles become ellipses as the form of the ship's red hull curves away on the left side.

Therefore, ellipses of light projected on a wall in front of us will slope upward to the right only if the sun is also coming from the right, as it is in this photo also.

Apparently N.C. Wyeth was unaware of this principle when he designed this otherwise fine illustration of Ben Franklin’s arrival in Philadelphia. The result is an error in lighting. According to the cast shadows from Franklin’s leg and from the tree branch at the bottom of the picture, the light is coming from above and to the right. But the ellipses of light on the wall point impossibly to a light source above and to the left.

Further discussion of dappled light, with photographic examples, on Edward Tufte's website, link.

Tomorrow: Business Cards, Illustrated

Still Playing with Dinosaurs!

Happy St. Patrick's Day, everyone. Above, from a recent school visit.

Thanks to DaniDraws.com for mentioning me in today's post "75 Artist's You Must Know and How to Find Them." I'm really excited to be listed with so many artists I admire, and I appreciate the work it takes to gather a compendium of so many links.

Charley Parker of the blog Lines and Colors talks a bit more about DaniDraws in his post today.

Transparency of Water

When light rays angle down toward the surface of still water, some of the rays bounce off the surface (reflection) and some travel down into it (refraction). Thanks to refracted light, we’re able to see the bottom, and the water looks transparent.

This painting by the Russian landscapist Zhukovsky shows both reflections and transparency. (The image is from Agni Art, a good source for inexpensive prints of Russian paintings.)


Above, the water is almost entirely transparent, with just a few slithery slashes of blue sky reflections to suggest the moving stream. (From the John Singer Sargent Virtual Gallery, a website that catalogs all his works.)

In three previous posts: (Part 1, Part 2, Part 3) we looked at water reflections, but this time, let’s also consider transparency.
The relative amounts of reflected and refracted light depends on the angle that the rays touch the water surface. For this reason, when you look steeply down into water, it looks more transparent, and when you look straight out across the water, all you see are reflections.


In the lower right of this study, you can see the streambed because you’re looking steeply downward, but higher up in the scene, the blue reflections of the sky take over.

Same thing in the study below. There’s mostly sky reflection at (1) and there’s more transparency at (2). In the area marked (3), the tones of the riverbottom are darker because the reflected skylight is interrupted by the mass of the rock. Polarized sunglasses will also selectively remove some of the glare of reflected skylight, allowing you to see more of the transparency (or refracted) rays.


In (4) you can see the edge of the last high tide. The tide was coming in as I painted this, covering the rocks one by one, and darkening them as it did so. Because blue light is scattered away and subtracted from the light illuminating subsurface rocks, they look darker and warmer than the rocks above the surface.

Gorilla Portraits

If you want to draw portraits of great apes, you have to approach them in the proper way. You can’t just march up to a great ape enclosure and start staring at them, or they’ll get all shy and disgusted and turn their back on you, because staring is a threat to them.

Yesterday we went to the North Carolina Zoo, the third largest zoo in the U.S.A. We got there early in the day when the gorillas were just waking up.

I remembered something I learned in my primate social behavior class. I approached the glass with a submissive posture, looking down at the ground and backing up with my hand out.

The gorilla loved it. She had never seen a human act like a polite ape before. She came right up to the glass and posed for me while I did this half-hour portrait from just two feet away. It was like sketching someone on a subway. I tried to just glance at her discreetly out of the corner of my eye.

I tried the same approach on the chimpanzee, an wild-born 33-year-old male named “H.N.”

He watched me draw with tremendous interest.


Every ten minutes or so he wanted me to show him how I was coming along on the sketch.

Traffic Cones

No urban painter is properly equipped without traffic cones.

Before you begin painting a street scene, place two cones in the street in front of you to secure the view. If you don’t, a 12-foot high delivery truck will park right in front of you.

No one will question the authority of traffic cones, especially if you stencil them with official-looking markings.

They also come in handy as distinctive apparel to wear to gallery openings.

Automotive Zeitgeist

What do the faces on cars tell us about the evolution of our zeitgeist?

Backlit Branches

I did this quick 3.5 x 5 inch watercolor a few days ago in Cambridge, Massachusetts. What interested me was the area where the trees are in front of the shadow side of the building.

The sunlight is coming toward us from the right side. The end of the building is in shadow. This sets up a perfect backdrop for showing the light gray mass of branches catching the morning sunshine. The stripes of rooftiles can just be discerned through the branches.

As often happens in plein air studies, the amount of detail in the scene is almost infinitely complex. You can’t possibly capture every tiny branch and detail, especially at this scale, so the challenge becomes how best to suggest more than you actually define.

I splayed out the tip of the watercolor brush and drybrushed around the light branches, and also drybrushed the branches that were darker than the sky. After everything was dry, I scratched out a few more branches with the tip of a folding knife.


It’s interesting (and a little embarrassing) to compare the photo after the fact. The drawing errors in scale and perspective become obvious right away. I missed a lot of color that was going on in the shadow. But I’m surprised that the photo seems to have completely missed the quality I liked best about the scene—the backlit bare branches.

Politics, Prose and Painting

Yesterday at Politics and Prose bookstore in Washington, DC, 110 fourth-graders from three different schools attended my PowerPoint and Magic Marker presentation.

Afterwards I met up with my artist friends Patrick O’Brien (left) and Armand Cabrera (right).

Armand and I set up our pochade boxes to paint the Chinese restaurant across the street from the bookstore. Jeanette stood, holding her watercolor sketchbook. There was a steady stream of curious spectators on the busy sidewalk behind us.

Two guys stopped on their way to delivering beer to a pub called Buck’s Hunting and Fishing. They wondered if we were having a painting contest. (photo courtesy Patrick O’Brien).

Here are the Three Stooges deep in concentration.

An old man stopped beside me. He folded a newspaper and put it under his arm. “Something you might want to know about that building,” he said. “The guy who owned it in the 1940s baked German pastries for President Roosevelt. He baked them right there in that building.”

“Didn’t someone have to taste the food to make sure it wasn’t poisoned?” I asked. He just laughed. “It was different in those days.”

One by one the chefs from the restaurant ran across Connecticut Avenue to see what we were doing. They commented among themselves in Chinese. After they returned, a big cloud of garlic smoke billowed out from the exhaust vent.

A little kid came by, dragging his mom. “That’s AWESOME,” he said.


A woman with a shiny purse said, “Why are you painting that place? It is the ugliest building around here.” Then she looked at my picture. “But you made it look beautiful.” I told her that I tried to paint it just the way it was without changing anything.


Here’s my painting in two different stages. Some of the construction lines, drawn in umber with a bristle brush, still appear in the block-in at left. At right was how it looked when I quit.

The painting wasn’t really finished, just abandoned after about two and a half hours. Near the end of the afternoon, the sun popped out from behind the clouds, bleaching out the pink and green colors of the awning.

Tomorrow: Backlit Bare Branches

Art By Committee Results

We've been playing an occasional group sketch game called "Art By Committee," where I share an an actual excerpt taken out of context from a science fiction manuscript and we see how a few of us mad illustrators put a picture to it. Below is another example taken from the original sketchbook.


What follows are the zany, witty, and wonderful sketches that you all came up with for the line: "I never understood why you were with him in the first place," followed by the one that originally appeared in my book. Thanks again for contributing. Let's take a break for a week because I'm on the road, but I'll toss out another line in the future.

Austin Madison

Arthur Keegan
Topher Sipes

Sarah Stevenson

Michael Dambold
Matthew Kalamidas


Jen Zeller

Davis Ottoson
Dan Pinto

...and the Coffeeshop Clan--Jeanette, Me, and James Warhola

Tomorrow: Politics, Prose, and Painting

Skyholes

A tree presents a complex silhouette against the sky, but the silhouette is almost never completely solid. A few “skyholes” puncture the shape of the tree and let you see through to the light beyond.


In this detail of a Claude Lorrain, there are fewer than ten skyholes painted in the lower third of the main tree. I’ve noticed that the early landscapists were sparing with skyholes.


This detail by Corot shows skyholes nearer the top margin of the trees. Some appear as fairly active circular shapes, which draws attention to them.


Constant Troyon, as seen in this detail, painted skyholes of various sizes, and gave them a ragged character, to suggest that they were fringed with leaves.

One question that every painter in opaque media like oil, gouache, or acrylic faces: Should you paint a skyhole with the same exact color as the sky beyond?


If you compare a photograph to the paintings we’ve seen, it appears much more complex and full of infinite variety. In the center of the photo I’ve placed the number 1 next to a prominent skyhole, and the number 2 surrounded by a group of smaller skyholes.


An enlargement reveals that while the larger skyhole does present an uninterrupted view of the sky, the smaller skyholes contain a network of fine branches and tiny leaves that weren't apparent from a distance.

These tiny interruptions lessen the amount of light passing through from the sky. As a result, these skyholes should really be painted a little darker than the actual sky color beyond.

Images from ARC, Link.

Tomorrow: Your Art-by-Committee Sketches