Craig, Understanding Augmented Reality (Chapter 2 – Augmented Reality Concepts)
In Chapter two,
Craig outlines concepts related to augmented reality. Specifically, he
discusses depth cues, defining them as “information used to determine how far
away things are from us and how we understand the three-dimensional world we
live in” (59). The information in this section sounded somewhat familiar, and I
connected the teachings to my experiences with optical illusions. I wondered:
How are these two concepts (augmented reality and optical illusions) related?
After all, they come from the same family, don’t they? — They’re visually perceived
images that add information to our physical world. Both seem to help (or
challenge) us to understand the three-dimensional world we live in, as Craig
describes.
He writes that “artists have used these ‘tricks’ for hundreds of years,” and I immediately thought of similar tricks as they are used to create illusions (59). I consulted Wikipedia for a quick refresher on optical illusions, and the language used to describe these artistic representations somewhat mimicked that used when describing AR. In following along with the characteristics of monoscopic image depth, I’ve provided pictures of optical illusions that might correspond with some of the cues:
Shading:
He writes that “artists have used these ‘tricks’ for hundreds of years,” and I immediately thought of similar tricks as they are used to create illusions (59). I consulted Wikipedia for a quick refresher on optical illusions, and the language used to describe these artistic representations somewhat mimicked that used when describing AR. In following along with the characteristics of monoscopic image depth, I’ve provided pictures of optical illusions that might correspond with some of the cues:
Shading:
Craig tells
readers “shadows give us clues as to where objects are in a three-dimensional
world” (60). This optical illusion uses shading to manipulate the design, providing
viewers with an altered perspective and perhaps inaccurate information about
the scene they are viewing. The scene depicts a checkerboard with light and
dark squares, and the illusion is that square A is actually the same color as
square B. See how it’s done.
Size:
Traditionally,
size allows us to note which of two objects is smaller and farther away. Craig
points out this too, noting “the size that objects appear to be gives us clues
as to their distance” (60). This optical illusion denotes this through tricks. In
this image, the corridor appears to look 3D, thus making both vertical lines
seem different in length. The illusion asks viewers to guess which line in
bigger (longer in length), when both lines are actually the same. 
Linear Perspective and Height
in the Visual Field:
In the outer two examples here, parallel lines
are used to portray size, length and height. While the lines appear to be
different, they are the same length. Take the example of the man and the boy:
Both figures are of equal height, but their association and placement in
relationship to one another makes the man appear taller. This placement, in
combination with the use of vertical lines and checkerboard pattern, allows the
viewer to make judgments based on what he appears himself to see. 
Brightness:
While similar to
the shading cue, brightness places an effect on optical illusions with the help
of color. This example uses a color gradient as a background to the image, thus
the horizontal bar appears to be changing in color.
I’d be interested in having a class discussion on this topic, as I think we would be able to uncover some cool concepts at play here that AR has to share. In looking around the web, I found the following video that showcases an augmented optical illusion. Check it out here.
Sources:
Craig, A. B.
(2013). Augmented Reality Concepts. Understanding
augmented reality: Concepts and applications (39-67). New York: Elsevier.Optical illusion. (n.d.). In Wikipedia. Retrieved September 13, 2013, from http://en.wikipedia.org/wiki/Optical_illusion
“Optical illusion: from Reality to Augmented.” 9 November 2010. YouTube. Accessed on 13 September 2013. Web.
Image Links:
http://en.wikipedia.org/wiki/Checker_shadow_illusion
http://www.moillusions.com/category/relative-sizes-optical-illusions
http://gibbysfrenchfryreport.blogspot.com/2010/10/foghorns-lesson-in-illusion.html
http://chestofbooks.com/business/psychology/Achievement/Chapter-III-Sensory-Illusions-And-Suggestions-For-Their-Use.html#.UjN4UbzFau4
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