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Pick up a clicker, find the right channel, and enter Student ID. Upcoming Deadlines. Homework #12 –Cameras and Lights in Maya Due Tuesday, May 8 th (Next week) 20 points (10 points if late) Homework #13 – Creating Stereoscopic 3D Images Due Tuesday, May 15 th (Last day of classes) - PowerPoint PPT Presentation

Transcript of Upcoming Deadlines

  • Upcoming DeadlinesHomework #12 Cameras and Lights in MayaDue Tuesday, May 8th (Next week)20 points (10 points if late)

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

    For full schedule, visit course website:ArtPhysics123.pbworks.comPick up a clicker, find the right channel, and enter Student ID

  • Homework #12For this assignment you are given a photograph of a real object and you will try to match the camera and the lighting.

    Each person will have a choice of four photos; for the assignment match any one of these photos (for extra credit, do more than one).

    To find the photographs assigned to you, go to:


  • Photo

  • Homework #12The Maya model for this "widget" object has been created for you and may be downloaded here:


    Open the object in Maya, create a surface for it to sit on, position the camera, add some lights, and adjust everything until your rendered Maya image looks as closely as possible to the photograph.

    Try to match any colors, for the object and the lights, as well as the details of the shadows (e.g., penumbra angles, ambient light, drop-off).

  • Maya Render

  • Homework #12To finish, move the position of your camera to view the scene from another direction (suggest that you turn the camera roughly 45 degrees to either side). Render #1Render #2

  • Homework #12Finally, upload the photo you chose to use and the two Maya rendered images into a posting entitled "Recreating Cameras and Lights in Maya."

    Note that this is a new assignment this year so there are no examples from previous semesters; contact me if you have any questions.

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

  • Homework #12Non-Maya Alternative: One of the four photographs is a pair of soup cans. Recreate the camera and lighting in that photograph as accurately as possible then take your own photos of the scene.

    Finish by taking a second photograph with the camera at about 45 degrees to either side of its original position.

    Upload both of your photographs as well as the photograph that you're matching.

    Note that it will not be easy to duplicate the lighting conditions using common house lamps; only do this alternative if you find it absolutely impossible to work with Maya.

  • Final ExamFinal exam is on Tuesday, May 22nd from 1215 to 1430 in this classroom.

    Final Exam will have of 10 short essay questions on material covered in lecture.Final exam counts for 50 points.

    You may bring one page of notes double-sided (or two pages single-sided) to the exam.

  • Final ExamVisit the course website for more info on your final exam (including sample).

    Note that the final exam is optional. All Assignments and Extra Credit must be turned in by 5pm on May 22nd

  • Special EventPIXAR presentation on "Brave" in Washington Square Room 109 at 3:30pm today.

    Go immediately after class if you hope to get a seat!

  • Survey QuestionFrom which of these assignments did you learn the most:

    Term papersHomeworks using TrackerStop-motion animation homeworksHomeworks using MayaReverse video reference

  • Review QuestionWhich path does light ray take after entering the water?

    Path A Path B Path C Path DDCBA

  • Law of RefractionC) Path C

    Angle is smaller in the denser material.

    The light ray bends but does not cross the normal (line perpendicular to the surface)

  • Review QuestionWhat looks like a pool of water in this photo is actually a mirage image of the sky created due to the desert heat.Mirages are produced by:


  • MiragesHot AirCool AirA) RefractionMirages are caused by the refraction of air because hot air has lower optical density than cold air.

  • Review QuestionNatural lighting underwater is primarily from overhead because sunlight cannot enter the water at more than about a 45 degree angle.True or False?

  • Total Internal ReflectionTrue.

    For the same reason you can only see the sky from underwater when looking up at more than about a 45 degree angle. See skyMirror

  • Optics & LightingPart IV: Scattering

  • Elements of OpticsLight SourceRefractionScatteringEye-BrainReflection

  • DW Consulting ExampleDisco lights for Intel commercial

  • Basic ScatteringSome sunlight is scattered, making the fog visible.

  • Scattering Out & Scattering InTo this viewer, the fog has scattered out some of the light so the sun isnt as brightTo this viewer, the fog has scattered in some light so the fog is visible.

  • 40%10%For example, if 40% of the light is scattered and 10% is absorbed then 50% directly reaches viewer. 100%50%Scattering vs. AbsorptionScattering is a deflection of the light.Absorption is an elimination of light.

  • 40%10%Extinction is 50% in both cases.100%50%ExtinctionExtinction defined as absorption plus scattering.10%40%100%50%40% scattered 10% absorbed10% scattered 40% absorbed

  • Demo: Scattering vs. AbsorptionBeakers filled with water placed on overhead projector.Beaker has drop of white ink, the other has a drop of black ink.What is seen on the screen??

  • Demo: Scattering vs. AbsorptionGlass dishes filled with water placed on overhead projector.One dish has drop of milk, the other has a drop of black ink.Projected image has two dark spots.Black ink absorbs light.White ink scatters light.

  • Particle Sizes & ScatteringTiny Particles (Rayleigh Scattering)Small Particles (Mie Scattering)Large Particles (Reflection/ Refraction)AirCloudBirds

  • Particle Sizes & ColorTiny Particles Scatter blue light the most, red the least; white light scattered with a hue shift to blue.Air moleculesGas fumesFine smokeParticles smaller than wavelength of visible light.Rayleigh Scattering

  • Rayleigh Scattering by Color0 200 nm 400 nmScattering StrengthParticle SizeFor tiny particles (under 400 nm) scattering is strongest for blue light and weakest for red light.Blue light: 440 nmGreen light: 550 nmRed light: 660 nm

  • Tyndall ScatteringTyndall scattering is very similar to Rayleigh scattering since both are the scattering of light (especially blue light) by very small particles.Opalescent glassBlue iris

  • Demo: Aerogel OpalescenceAerogel is ultralight, hard foam made from SuperGlue.

    Scattering makes aerogel look blue while the transmitted light is yellow.Flashlight shines white light on a piece of aerogel

  • Particle Sizes & ColorSmall Particles Scattering of hues varies with particle size, usually averaging out to white.CloudsWhite paintMilkParticles comparable to wavelength of visible light.Mie Scattering

  • Mie Scattering by Color400 nm 800 nm 1200 nm Scattering StrengthParticle SizeFor small particles Mie scattering strength varies greatly with the particle size.

    Since particles tend to be a mix of sizes, all hues are scattered equally resulting in white.Blue light: 440 nmGreen light: 550 nmRed light: 660 nm

  • Particle Sizes & ColorLarge Particles Reflect light off the surface or, if transparent, refract and transmit light.RainSandConfettiParticles much larger than the wavelength of visible light.

  • Suspended ParticlesA dust storm is seen from the reflection off the suspended dust particles rather than true scattering.Mie scattering by water droplets in clouds.

    Reflection from suspended particles.

  • Volumetric LightingVolumetric lighting is used to create the volume of scattered light, usually due to Mie scattering in dust or fog.

  • Scattering & AngleDirection of light scattering is not random.More lightLess lightForwardBackward

  • Mie Scattering & AngleMie scattering is strongest in the forward and weakest backward directions.Fog

  • Mie Forward ScatteringFogDrier VentSun is behind the fog in this photoCameraSunMie scattering from drier fog

  • Mie Backward ScatteringFogDrier VentSun is behind the camera in this photoCameraSunMie scattering from drier fog

  • Sun RaysTo cameraTo cameraIntensity of sun rays varies with the angle between sun and viewer.Notice that the light on the ground is bright even though the rays intensity appears to taper off along the sun ray.Mie scattering by fog mist

  • Rayleigh Scattering & AngleRayleigh scattering is strongest in the forward and backward directions.It is weakest to the sides (90 degrees).Gas fumes

  • Brightness of the SkyThe darkest part of the sky tends to be about 90 degrees from the direction of the sun.Rayleigh scattering by air moleculesFrom Sun

  • Single vs. Multiple ScatteringLight rays may scatter multiple times, if the scattering medium is dense.Light FogHeavy Fog

  • Demo: Scattering in a Fish TankSingle versus multiple scattering is nicely shown by shining a flashlight into an aquarium filled with clean water then adding more and more milk.

  • Single Scattering in a Fish TankFlashlightSingle scattering produces a narrow beam of light.Mie scattering by very dilute water/milk mix.

  • Single Scattering in a Fish TankFlashlightIntensity differences due to scattering angle (i.e., near the light we have more forward scattering).To cameraTo camera

  • Multiple Scattering in a Fish TankFlashlightMultiple scattering produces a diffuse beam of light.Hue shift from white (near flashlight) to orange-red on t