Friday, December 28, 2007

Water Reflections, Part 1

When a scene is reflected in water, it appears almost like an inverted mirror image.

Almost. But the reflection is different in a few important ways. First off, the light tones that you see in the scene above the water will appear a little darker in the reflection. These light tones might be clouds in the sky, a white house, or light-colored leaves on riverside plants.

The reason these light tones appear a little darker in the reflection is that some of the light penetrates into the water, rather than bouncing off the surface. This light is the very same light that you would see if you were snorkeling under the surface. If water were a perfect mirror, fish would live in pitch darkness! Because each parcel of light is reduced by the amount of light that is diverted into the water, the amount of light reflected is also reduced.


Note how the colors of both the blue sky and the orange bush darken when they're reflected in this wintry stream.

Water approaches the reflectivity of a perfect mirror only when you’re looking straight across it at a very shallow angle. As the steepness of the angle of reflection increases, the percentage of light entering the water also increases. If you are looking steeply down onto the surface of the water, not much light from the sky will be reflected. Think how dark the water in a lake or ocean appears when you look straight down into it from the side of a boat.


This light-eating phenomenon (called refraction, as opposed to reflection) came into play in this painting of a white resort perched above a lake. I was looking downward on the water, and was surprised how poorly the water reflected the white rocks along the lake's edge and the light stones on the building. I painted it the way I saw it, but it still looks strange to me.

As a reality check, here's a photo of the same place, shot with a steep downward angle. It shows the same effect, with most of the light tones disappearing into the water, rather than reflecting off its surface.

7 comments:

Anonymous said...

Right : refraction of light happens when light cross the air and then, something else, as water, also TRANSPARENT. The direction of the movinglight changes. As a consequence also the angle size you explain.

Sylvia
arimathee.blogspot.com

Dan G. said...

Interesting post. I'm glad, for fish, that water isn't a perfect mirror!

Now I understand more clearly why I always had trouble with children's stories where characters look down into a pond or a stream and clearly see their reflection, as if they were peering into a mirror.

It can't happen that way!

When you down into water, the light is being absorbed, so very little reflection would occur. Plus, the light in such a situation would emanate from the sky above; the reflection would be a silhouette of the head, not a lighted face. The face would be on the dark, shaded side of the head.

I love your blog. It's kind of like opening a present under the tree every morning.

Tom Scholes said...

Thanks for another tasty and educational morsel!

Marc said...

Great post! The only thing I would add is that choppy water will scatter the light more and thus look much less reflective from afar. This might be obvious to experienced painters, but not so apparent for beginners.

I have admired your work for a while but just recently discovered your blog. It is fascinating to see your painting and thinking process. Thanks so much for sharing this.

Maria Arnt said...

I've noticed this phenomenon in the past, where an object lighter than the sky reflects darker than the sky in the water. At the time I thought it was because the sky is sort of a dim ambient light, and the "reflection" of the object was a little more like a "sky-shadow" meaning that it blocked out that ambient, slightly glowy light. I don't have any science to back that up though. Does it make sense to you?

James Gurney said...

Maria, I'm glad you mentioned that because I've noticed it too, and always wondered about it. Your explanation sounds very good. Let me ponder it a bit, too, and see what I can come up with.

Wayne said...

I thought I'd throw my 2c in regarding the dark reflection of light objects, specifically the white buildings reflecting dark.

I'm guessing the sky in this scene was overcast or mostly overcast hence the soft flat light on the buildings. This means a very bright sky relative to the building IF you were down at the water surface looking up at the building which would appear much darker against a fairly bright background. Allow for light absorption into the water which makes the reflection slightly darker again.

If you were to photograph a light valued building against a bright sky and expose the image in such a way as to mimic the luminosity of water reflection ie under expose the photo, you will most likely get close to that reflection.

Carlson talks about the four planes, uprights being the darkest, (I know he was talking about trees but the theory holds) and that the lightest part of the scene, regardless of what the light is falling upon, will always be brightest in the sky, as it is the source of light. Any light reflecting off upright surfaces will be minimal COMPARED to the light source.

I think this is what is happening at least!