Upcoming Deadlines

Homework #11 – Building a Scene in MayaDue Tuesday, May 1st 20 points (10 points if late)

Homework #12 –Cameras and Lights in MayaDue Tuesday, May 8th 20 points (10 points if late)

For full schedule, visit course website:ArtPhysics123.pbworks.com

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Second Term Paper

The following persons did not turn in their second term paper in on time:

6495047 57605217687693 5862857

The term papers will be graded over the next two weeks, hopefully even sooner.

Homework #11

For this assignment you will create a simple scene using Autodesk Maya, a popular software application used in animation.

You can download a 30-day trial version of Maya from the Autodesk website.

You will also use Maya in Homework #12 where you will try to recreate the camera and lighting for a simple composition.

Homework #11

The scene that you create in this assignment consists of a floor, a single wall in the background, and some objects in the foreground.

Those objects need to be arranged so that they create the shape of the initials of your name.

Position the two letters so that they rest on the floor or on each other; do not have themtouching the vertical wall.

Homework #11

This scene was created by Tom McKee.

Homework #11

Post your rendered image on blog in an entry entitled “Building a Scene in Maya.”

Due by 8am on Tuesday, May 1st 20 points (if late, 10 points)

Extra Credit (10 points):Create images of your scene lit using one-point, two-point, and three-point lighting.

Homework #11

One-pointLighting

Three-pointLighting

Two-pointLighting

Survey QuestionWhat grade do you expect to get in this course?

A) A (400 points or more)

B) B (300 points or more)

C) C (200 points or more)

D) D or below (Below 200 points)

E) Have no idea

Review Question

Which of these is not a mechanism for heat transfer?

A) ConductionB) RadiationC) ReductionD) Convection

Heat Transfer

C) Reduction

Conduction

Convection

Radiation

Review Question

Flowing electrons strike atoms in a conductor, heating the material.

This type of heating is named after:

A)André-Marie Ampère

B)Nicola Tesla

C)Thomas Edison

D)Georg Ohm

E)Alessandro Volta

Toaster

Ohmic HeatingGeorg Simon Ohm (1789 –1854) was a German physicist. As a high school teacher, Ohm began his research with the recently invented electrochemical cell, invented by Italian Count Alessandro Volta.

Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current – now known as Ohm's law.

Ohmic heating is also called Joule heating, first studied by James Prescott Joule in 1841

Georg Ohm

Review Question

Electrocution (death by electric shock) is usually due to ohmic heating of the internal organs of the body.

True or False

Electrocution

False

It is due to the disruption of the nervous system, especially that which controls the heart beat.

Nervous System

Nervous systems in animals use electrical currents to signal the contraction and relaxation of muscles.

The most important electrical signal in our body is the periodic signal that contracts and relaxes our heart muscle to pump blood.

Without a constant flow of blood the brain can suffer permanent damage.

SA

AV

Optics & Lighting I: Lights and Shadows

Lighting

Lighting is important in all the visual arts, from painting to cinematography.

The Orrery, Joseph Wright (1766) Humphrey Bogart in The Maltese Falcon (1941)

Up (2009)

Let’s look at how lighting in used in a scene from Pixar’s Up.

Up (2009)

Up (2009)

Up (2009)

Key Lighting (One-Point)

Simplest type of lighting is with a single dominant light source, called the key.

Traditionally, this light source is located on the left side of the scene.

Utah Teapot

The Utah teapot or Newell teapot is a 3D computer model which has become a standard reference object (and an in-joke) in the computer graphics community.

It is a mathematical model of an ordinary teapot of fairly simple shape, which appears solid, cylindrical and partially convex.

The teapot model was created in 1975 by early computer graphics researcher Martin Newell at the University of Utah.

Cast Shadows & Form Shadows

Form ShadowCast Shadow

Cast Shadows

Size and sharpness of a cast shadow depends on:• Size of the light source• Distance from light to object• Distance from light to wall

Cast Shadow for Directional Light

UMBRA

Object

Wa

ll

A directional light has parallel light rays so the cast shadow is simple to trace on the wall.Dark shadow called the umbra.

Shadow is sharp (not fuzzy).

Creating Directional Light

Light sources, such as bulbs, send light in all directions; directional lighting is created with mirrors or lenses to form the light into a beam.

“Barn doors”

Cast Shadow for Point Light Source

UMBRA

Light source(Point)

Object

Wa

ll

Shadow is sharp (not fuzzy).

Size of shadow depends on:* Distance from the light to object* Distance from object to wall

Light rays spread out from a point light source, such as a bright light bulb or a candle.

Film Noir Shadows

Shadow Of A Doubt (1943)

M (1931)

Film noir makes extensive use of cast shadows, manipulating their size for dramatic effect.

I Confess (1953)

Cast Shadow for Area Lights

UMBRA

Penumbra

PenumbraLight source

Object

Wa

ll

Rays from a large light source to wall to map out location of deep shadow (umbra) and fuzzy shadow (penumbra).

The larger the light source, the smaller the umbra.

Umbra and Penumbra

An ant on the ground standing in the penumbra could see part of the sun.

Standing in the umbra part of the shadow, the ant wouldn’t see the sun at all.

No Shadow

Penumbra

Umbra

Penumbra Size

Notice how the size of the shadows’ penumbra increases as the shadow gets farther from the base of the tree.

Very far from the base the penumbras on each side meet and there’s no more umbra.

Solar Shadows

UMBRA

Penumbra

Sun

Object

The width of the penumbra for a shadow cast by the Sun equals about 1% of the distance from the object to its shadow.

Floor

Angle = ½ degree

()

Distance

Diagram is not to scale

LIGHT

Example: If an object is 9 feet (108 inches) from the ground, the penumbra is a little more than 1 inch wide.

Size of the Sun and Moon

In the sky, the sun and the moon are about the size of a dime viewed from a distance of six feet.

The Starry Night, van Gogh (29 in × 36¼ in)

Paintings with the sun or the moon rarely show it at the correct size for the distance at which the painting is normally viewed.

Moonrise Illusionhttp://antwrp.gsfc.nasa.gov/apod/ap020130.html

Is the Moon larger when near the horizon? No, the Moon is very nearly the same size no matter its location on the sky. In this time-lapse sequence, the Moon was re-imaged every 2.5 minutes, with the last exposure of longer duration to show the panorama of Seattle.

The illusion occurs because foreground objects make a horizon Moon seem to be farther in the distance. The mind interprets more distant objects as wider; furthermore the distance illusion may make the eye focus differently.

Sun Rays

See rays because part of the light is blocked by clouds

Fog ShadowsShadow seen due to scattering by fog of the non-shadowed light rays.

Fog shadow of TransAmerica building.

Sun Rays & Perspective

Light from the sun is nearly parallel so we see spreading ray pattern due to perspective.

Sun Rays & Perspective

This is what you think you see

This is what the sun’s rays are actually doing

Sun Rays & Perspective

Compare reality with perception

Sun Rays & Perspective

Shadows & Perspective

Mt. Teide, Canary Islands

Mauna Kea, Hawai'i

These photos show the long shadows cast by tall mountains at sunset, with the moon rising near the horizon.

Notice the shadows’ sharper peaks, due to convergence of lines by perspective.

Lighting and Dimension

Intensity of light striking a surface varies with angle so the gradient created by a key light is a strong visual cue of an object’s curvature and shape.

Light Intensity & Distance

The intensity of light decreases as we get farther from the light source.

For a point light the intensity decreases quadratically, that is, at twice the distance you have a four times less intensity.

The light gets weaker because it is spread over a larger area.

Demo: Perspective Cards

Hold large card at arm’s length.

Close one eye then hold small card at a distance such that it is same size as large card.

That distance will be half way between your eye and large card.

1

1 2

3 4

Arm’s length

Half

Area & Distance

These four figures are equally spaced indistance and, in perspective,you are standing that distance from the first.

At twice the distance,the face is ¼ the size.

At four times the distance face is 16th the size.

Light Intensity & Angle

As angle between the light and a surface increases, the intensity of the light on the surface decreases because it is spread over a larger area.

7 light rays hit surface

5 light rays hit surface

Summertime

It’s hotter in the summertime because in July the Earth is closer to the sun.

TrueorFalse

Seasons of the Year

False. Northern Hemisphere is warm in July because Earth is tilted towards the Sun.

Southern Hemisphere is cold in July since it’s tilted way from the Sun.

Equator

January in Brazil

Form Shadow for Point Light Source

Light source(Point)

Object

The form shadow is completely dark if point source is the only light source (i.e., no ambient or reflected light).

Object is brightest where the rays hit head-on and dims going up to the terminator.

Terminator

Form Shadow for Area Light Source

Light source(Area)

A B C

View from A View from B View from C

Terminator widens into a penumbra for an area light.

Ambient Light

Direct

Direct

DirectAmbient Ambient

Ambient

Most lighting is indirect, coming not from a light source but from reflections off of other surfaces.

Fill Lighting

Key

Fill

Key+Fill

With two-point lighting the fill light softens the contrast by adding ambient light.

Rim Lighting

Key+Fill

Rim

Key+Fill+Rim

Adding a rim light shining from behind distinguishes the foreground objects from the dark background.

Three-point Lighting

Key+Fill+Rim

Three-point lighting (Key, Fill, and Rim) is a formula that Hollywood has used for years.

From Casablanca (1942)

Three-point lighting usually looks good but sometimes too good, that is, it seems fake.

Next LectureShading & Reflection

Homework #11 (Building a Scene in Maya)Due on Tuesday of Next Week

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