What_is_Perception

8/11/2019 What_is_Perception

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Perception: Color, Vision, How We See

LIGHT is To The Environmental Designer

creating an atmosphere

creating a sense ofspace, both physically

and experientially/psychologically

describing materialsand surfaces

meeting the needs ofuse of the space

The Architect and Interior Designer are interested in theenvironmental impact of light .


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Designing with Light.

.. Is Perception.. Is Perception

An awareness of objects and other data throughthe medium of the senses: visual perception = seeing

Insight or intuition as an abstract quality: visual perception = projecting meaning on what

we see


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Light Sources

Generators

Transmitters

Secondary Light Sources

Modifiers and Re-transmitters

Eyes

Receivers

Encoders

Brain

Decoder

Interpreter

Sun, Discharge lamps,fluorescent lamps.

Incandescent lamps,Open flames, etc.

Atmosphere, Air, Water, Planets, Lenses,Windows, Tress All natural or

manufactured objects which modify lightwaves before they reach the eye.

Cornea, Iris, Lens,Rods & Cones,Optic Nerves

Analysis,IdentificationAssociationPerception

Visual System


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Structure of the Eye

CorneaIris

Lens

Retina

Fovea


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Light Entering the eye is projected upside down!


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Find your Blind Spot

4 inches apart

1. On a scrape piece of paper draw an X and a dot .

2. Hold the paper with your right hand in front of your face about 4-6 inches away.

3. Cover your left eye with your left hand and focus on the X with your right eye.

4. Flip the paper around for the left eye.


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Eyes Field of VisionCentral field of vision:

~2 degrees above and below the direct line of sight

Visual acuity (ability to see detail) is best in this rangePeripheral area:

Horizontal area to the sides of the central visionVertical areas above and below the central field of vision

Brightness and motion best seen in peripheral vision

central field of vision


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Cones and RodsThe interior back wall of the eyewall is the Retina containing light

sensitive cells a photoreceptorsknown as Rods and Cones

Rods - 120 million

principle for peripheral vision

and low light levels (ScotopicVision)

Cones - 8 million

responsible for normal(Photopic vision) and forfocusing on finedetail..cones also containpigment and allow to seecolorbut they can differ orsensitive


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Processing of Visual InformationColor Perceptionthis visual process provides us details regarding the color of a surface or anobject

the cones detect color..a normal person is trichromaticwe see all colorsColor Deficiencies in the Visual System - color blindness


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Color Perception


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Color Vision TestsConfusion lines form the basisof many color vision tests suchPseudoisochromatic plates.

Pseudoisochromatic platetests are also commonly used inthe clinic to screen for colorvision deficiency. Colors arecarefully chosen based on the

confusion lines.

The most commonly used pseudoisochromatic plate in theclinic would be the IshiharaIsochromatic plates (for

screening red-green colorvision deficiency) and theTritan (F-2) plate.

pseudoisochromatic adj. Being apparently of the same color, as of certain charts used in testing colorblindness


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Color Vision Tests


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Photopic Day Vision (Cones vision)

The cones of the eye are of three different types.These are the primary colors (additive) in light,which are red, green, and blue.

Scotopic Night Vision (Rods vision)

The rod is responsible for night and peripheral

vision.

Mesopic - Dim Light Vision (Rod and Cone vision)

This occurs when the light levels are low butthere still is the ability to see color (between .01and 1 cd/m 2 adaptation luminance).

Day & Night Vision


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Measuring VisionVisual Acuity (20/20Vision)Snellen Eye Chart: the firstnumber is refers to the distancefrom the chart, the second is whata normal person can read thechart.20/20 is normalbut,20/60 says that person could read20 feet what normal person canread at 60 feet

Contrast Sensitivity

Contrast Detection


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Effects of AgingYellowing of thelensOpacity of the lensLess Elastic Lens

Amount of light

reaching theRetinaTime required forVisual Process

Visual Acuity andSensitivitydecrease

Common Defects:

Myopia: cant focus on far objects (Near-sighted)

Hyperopia: cant focus on near objects (Farsightedness)

Astigmati sm: d is to rt ion in the shape of the lens

Presbyopia: lens loses it elasticity .corrected with bifocals to read near


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Visibility and Visual PerformanceContrast

SizeBackground LuminousViewing Time


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Can you read this?ContrastBackground Luminous

SizeLighting Lighting Lighting

Viewing Time


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Processing of Visual InformationDepth Perceptionthis visual process provides us details regarding the distance to an object

Your eye determines distance by 3 methods (size, moving, stereo)

The size a known object has on your r etina - If you have knowledge of the size of an objectfrom previous experience, then your brain can gauge the distance based on the size of the objecton the retina.

Pictorial cues .sizes of objects that you are similar with.books, chairs.light andshadow provide clues..directional light.

Moving parallax - When you move your head from side to side, objects that are close to you moverapidly across your retina. However, objects that are far away move very little. In this way, yourbrain can tell roughly how far something is from you.

Stereo vision - Each eye receives a different image of an object on its retina because each eye isabout 2 inches apart. This is especially true when an object is close to your eyes. This is lessuseful when objects are far away because the images on the retina become more identical thefarther they are from your eyes.

Binocular Clues seeing on object with both eyes..more information isprovidedstereo vision..a one eyed person lack depth perception


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Depth Perception


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Depth Perception - Binocular CuesBinocular rivalry can bedemonstrated by placing

your pen between yourselfand the computer screen.

Keep your eye on the tip ofyour pen and notice the

two bars merge.

What do they form?

(You may need to slowly

move the pen from thescreen toward you.)


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Depth Perception - Monocular Cues

Interposition: Interposition cuesoccur when there is overlapping ofobjects. The overlapped object isconsidered further away.

Relative Size: Retinal image size allow us

to judge distance based on our past andpresent experience and familiarity withsimilar objects. As the car drives away, theretinal image becomes smaller and smaller.We interpret this as the car getting furtherand further away. This is referred to as size

constancy. A retinal image of a small car isalso interpreted as a distant car.

P i C l Vi i H W S


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Light And Shade: Highlights and shadowscan provide information about an object'sdimensions and depth. Because our visualsystem assumes the light comes from above,a totally different perception is obtained if theimage is viewed upside down.

P i C l Vi i H W S


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Linear Perspective: Parallel lines suchas railway lines converge with increasingdistance.

Aerial Perspective: Mountains in thedistance appear more blue.

P ti C l Vi i H W S


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Depth Perception

Perception: Color Vision How We See


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A) Radial dot flow generated from a straight-line path across a ground plane. The direction of motion can be determinedby finding the focus of expansion, the point in the flow field where there is no horizontal or vertical motion. This may notbe explicitly present, but can be extrapolated from the motion of other points in the image. B) Curvilinear dot flowgenerated from a curved path across a ground plane, also with a fixed gaze.



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Monster Illusion



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The balconies on this New York apartment block either appear to tilt upwards or downwards dependingon the angle they are viewed from. The higher you look the stronger the appearance of the tilt



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Brightness Perceptionthis visual process provides us detailsregarding the brightness of a surface or anobject



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e cept o : Co o , V s o , ow We See



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Processing of Visual InformationMotion Detectionthis visual process provides us details regarding the motion to an object

Different cells respond to different type of movementand can adapt light lightlevels

Moving or static perceived movement in all directions is perceived

Our visual system is capable of taking a series of stationary views and ..andappears to be a continuous moving scene(ie individual frames in astroboscopic manner, such as movies)

Lamps strobeup to 120 times a second.



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Visual PerceptionThe modern view of visual perception is one of dynamicprocesses that go beyond the simple replication of visualinformation provided to the retina.

For over 80 years Gestalt psychologists have argued thatthe act of perception creates a Gestalt, a figure or form thatis not a property of an object observed but represents the

organization of sensations by the brain.

This dynamism is thought to be crucial for the performanceof simple, everyday visual tasks such as the recognition ofan object that is partially occluded. Thus, the study of howthe brain is capable of filling in the missing pieces is animportant topic; one that has most often been carried outthrough the use of illusory contours and optical illusions.



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Hering illusion



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Ouchi Illusion



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Stare at the black dot in the center and watch the colored spots dissappear!



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I cdnuolt blveiee taht I cluod aulaclty uesdnatnrdwaht I was rdanieg The phaonmneal pweor of thehmuan mnid Aoccdrnig to rscheearch taem atCmabrigde Uinervtisy, it deosn't mttaer in wahtoredr the ltteers in a wrod are, the olny iprmoatnttihng is taht the frist and lsat ltteer be in the rghitpclae. The rset can be a taotl mses and you can sitll

raed it wouthit a porbelm. Tihs is bcuseae thehuamn mnid deos not raed ervey lteter by istlef, butthe wrod as a wlohe. Such a cdonition is arppoiatelycllaed Typoglycemia :)-

Amzanig huh? Yaeh and yuo awlyas thoughtslpeling was ipmorantt.


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