Upcoming Deadlines

Homework #13 – Creating Stereoscopic 3D ImagesDue Tuesday, May 15th (Last day of classes)20 points (10 points if late)

Final Exam - Tuesday, May 22nd from 1215 to 1430 in this room.

All assignments and extra credit due on May 22nd

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

Pick up a clicker, find the right channel, and enter Student ID

Homework #13

Creating stereoscopic 3D images.

For this assignment you will create at least three different stereoscopic images from photographs.

At least one of the images should have you appearing in the photo and at least one of the images should be a recognizable location on campus.

You will be graded on the composition so plan your scenes to make them interesting (especially for 3D).

Stereo 3D Photos with Photoshop

Steps for creating stereo 3D photos in Photoshop:

1)Snap a photo, move 3 inches to the right, take a second photo. Avoid having objects closer than a yard away from the camera and no moving objects!2)Open both images in Photoshop. Hold the shift key and drag the right eye image on to left eye image.3)Rename the layers “Right Eye” and “Left Eye”; make sure the Right Eye layer is on top.4)Double click the Right Eye thumbnail to open the Blending Window. In Advanced Blending uncheck the Red Channel for Red/Cyan glasses (or Green Channel for Green/Magenta glasses).

Stereo 3D Photos with PhotoShop

Uncheck the Red Channel

Select Right Eye Layer

Homework #13

Course website has details and tips on making 3D photos.

Upload your photos to your blog in an entry entitled “Creating Stereoscopic 3D Images”

Extra Credit: You can also create a pair of stereo-ready images in Autodesk Maya by rendering a scene for one image, then shifting the camera position and rendering the second image.

Extra Credit: Create a 3D animated short, either by stop motion or in Maya. Ten bonus points for a good animation; twenty bonus points for a great one.

Student Evaluation

Need a volunteer to distribute and collect student evaluations.

Volunteer should deposit the packet of completed forms in the mailbox at front door of the building (exit to Tower Hall).

Evaluations

When finished, find me in Room 242

Survey Question

This course has four parts; which part was the least interesting for you:

A) Basic Animation (Falling, etc.)

B) Character Animation (Walks, etc.)

C) Effect Animation (Waves, etc.)

D) Lighting (Shadows, Color, etc.)

E) About the same for all four

Review Question

Red Cone

Green Cone

Blue Cone

What color do you see when your eye receives both red and blue photons?

A) YellowB) GreenC) MagentaD) CyanE) White

Review Question

C) Magenta

This is nicely demonstrated with the spinning Maxwell disk.

Review Question

The ear hears sound waves and senses the wavelength of the sound as the pitch.

The eye sees light waves and senses the wavelength of the light as color.

The ear doesn’t have a “lens” so it can’t form an image but otherwise the ear and the eye are very similar. True or False

The Ear vs. The Eye

AE D

How the ear senses sound waves is distinct from how the eye senses light waves.

Hearing an E and a D together does not sound like an A.

Seeing green and red together does look like yellow light.

Review QuestionIf you stare at a red cross for a few seconds and then look at a white wall, the after-image you see is cyan. What color is the after-image if the cross is blue?

A)RedB)YellowC)GreenD)MagentaE)Orange

Red cross

After-image

Blue cross

Negative After-image

Stare, unfocused, at the red cross for 10 seconds then look at white wall

Negative After-image

Yellow

Additive Complements

After-image of blue cross is yellow since blue cone gets tired so when white light excites all three cones, red & green cone signals are stronger than blue cone.

Yellow = White - Blue

R

GB

Making Color

Spectrum & Color

Wavelength

Brig

htne

ss

The color you see depends on the spectrum of the light waves reaching your eye.

X Y Z

Tristimulus Values

There’s a complicated mathematical formula to get the tristimulus values from the spectrum curve.

WavelengthB

righ

tne

ss

X = 0.2Y = 0.7Z = 0.1

Creating Colored Light

Two basic ways of creating colored light:

Light source produces colored light.

Absorb some of the light’s wavelengths.

Filter

Thermal Light Sources

When objects glow with heat they emit light in a broad spectrum, called the blackbody spectrum.

The peak of that spectrum shifts from red to blue as the temperature increases.

Thermal Light Sources

Notice that the color of thermal light sources goes from red (2000K) to blue (12000K) but it is never green.

Spectrum is broad around 6000K so we see it as white.

CIE “Color Wheel”

Solar Spectrum

UV Visible Infrared

Brig

htne

ss

Spectrum of the Sun is brightest in the range of wavelengths that are visible to us (adapted by evolution).

Sun is so bright at all visible wavelengths that it’s seen as white or unsaturated yellow.

Spectral Lines

Some light sources produce spectra with lines, indicating wavelengths for which the atoms have resonant oscillations.

Neon lamp

% Red Cone

% G

ree

n C

on

e

Neon lamps produce a well-saturated red, but not as pure as sodium lamp’s yellow

Spectral Reflectance Curves

                                                      

When white light shines on a colored object, some photons are absorbed, others are reflected by the object’s surface.

RedW

hite

Printing InksPrinting inks use only three bright pigments:

• Yellow• Magenta• Cyan

Yellow

Cyan

Magenta

Red

Green

Blue(also use black ink, which is cheaper than mixing for black)

Mixing Yellow & Cyan Inks

Bright Yellow

BrightCyan

BLUE GREEN RE

&

Green

Subtractive ColorFind mixture color by simple color “arithmetic.”

Yellow = Red+GreenCyan = Blue+GreenMagenta = Blue+Red

So mixing:Yellow & Cyan = Green

Yellow

Red

R

Y

B G

M

C

Yellow

Cyan

Magenta

Red

Green

Blue

Four Color PrintingMagenta Yellow Cyan Black

Magenta+ Yellow+ Cyan

All Four

Green balloon printed with mix of yellow and cyan inks

Paint Pigments

Paints are suspensions of pigment particles.

Different types of paint (watercolor, acrylic, oil, gouache, etc.) are just different binding solutions for holding pigment.

Name That Pigment

Titanium White

Cadmium Red

Burnt Sienna

BLUE GREEN RED

0%

100%BLUE GREEN RED BLUE GREEN RED

Re

flect

an

ce P

erce

nta

ge

Name That Pigment

Phthalocyanine Green

Cadmium Yellow

Cobalt Blue

BLUE GREEN RED

0%

100%BLUE GREEN RED BLUE GREEN RED

Re

flect

an

ce P

erce

nta

ge

Artist’s Handbook

These spectral reflectance curves and those of many other standard pigments are found in Mayer’s book.

Color Subtraction

% Red Cone

% G

ree

n C

on

e

Combining pigments is more complicated and the resulting

color is difficult to predict.Learn by practice Green

paint

Red paint

Dark Brown

Mixing Yellow & Blue Paint

% Red Cone

% G

ree

n C

on

e

Mixtures of yellow and blue paint often mix to green

Bluepaint

Yellowpaint

Green

By contrast, adding yellow and blue lights

gives white light

Mixing Yellow & Blue

Bright Yellow

Blue

&

Bluish Green

Yellow absorbs much of the Blue

Blue absorbs much of the Red

Ref

lect

ance

%

Mixing Red & Blue

Blue

&

Crap

Red

Reflectance curves for pigments and their mixture

Effect of the Light Source

                                                      

The color of an object depends on both the spectral reflectance curve and on the spectrum of the light shining on the object.

White

RedGreen ?

Magenta ?

Same “red” object in different lights

Pigment Value & Light Source

Yellow pigment under blue light is dark gray.

Cadmium Yellow

BLUE GREEN RED

Put paint swatch in this area

Pigment Value & Light Source

Yellow pigment under red light is bright red

Cadmium Yellow

BLUE GREEN RED

Put paint swatch in this area

Demo: AlexandriteThe color change from red to green is due to strong absorption of light in a narrow yellow portion of the spectrum, while allowing large bands of blue-greener and red wavelengths to be transmitted. Typically, alexandrite has an emerald-green color in daylight (relatively blue illumination of high color temperature) but exhibits a raspberry-red color in incandescent light (relatively yellow illumination).

Sunlight or FlorescentIncandescent light

Demo: Sodium Lamp

Sodium lamps produce a true, spectral yellow light

Pile of toy balloons

Demo: Sodium Lamp

Sodium light

Florescent light

Light Source, Value, Saturation

                                                      

The value and saturation of an object’s color also depend on the spectrum and the intensity of the light shining on the object.

DimRed

Same “red” object in different lights

Bright Pink

Saturation & Value

High Value andLow Saturation

Low Value andHigh Saturation

As lighting conditions change, value and saturation usually vary together.

Valu

e

Saturation

Valu

e

Saturation

Black, White, Gray

% Red Cone

% G

ree

n C

on

e

33 %

33%

33%

Black, white, and gray are all the same hue, just different

values (brightness)

Experiment

Photographed black felt and white flannel tablecloths

Black or White?

Black or White?

Black or White?

Black Paint

Black paint reflects more light (has higher value) than you may think.

Compare the value of the matte black paint with that of the holes.

True Black

The closest you can get to true black is a hole that lets light in but not back out.

Surprisingly, even the lunch box painted white inside doesn’t reflect much light out the hole.

White in the shadow is darker than black in the light.

Last LectureStereoscopic (3D) Films*Bring Your 3D Glasses*

Homework 13 (Creating 3D Images) due Tuesday, May 15th (Last day of Class)

Please turn off and return the clickers!