Anaglyph 3-D
Complimentary Lesson Plan
Take a look at a 3-D comic book through 3-D glasses. What is happening? The bluish lenses filter covers the right eye and the red filter covers the left eye. The drawings and photographs are done in adjacent red and blue outlines. Where the red (or orangish) and blue overlap, there is brown. Through the 3-D glasses the red and blue drawings merge into one black drawing. Why?
· Close your left eye. What happens? (The black drawing shifts to the right)
· Close your right eye. What happens? (The black drawing shifts to the left.
· Look through the red lens at the red and blue drawings. What happens? (The red drawing disappears and the
Blue drawing turns black)
· Look through the blue lens at the red and blue drawings. What happens? (The blue drawing mostly disappears and the red drawing turns black)
Ask students to describe and explain what they see. Explain that the blue drawing looks black when viewed through the red filter because no blue or green gets through the red filter. Only red and orange pass through the red filter. Orange does pass through the red filter along with the red. The red and orange of the white paper also pass through the red filter. The orange drawing disappears because the red and orange of the white paper and of the orange drawing pass through the filter. The two look the same.
The orange drawing looks black when viewed through the blue filter because the blue filter does not transmit the orange and red of the orange drawing. Since orange and red cannot pass through the blue filter, the orange drawing looks black. The blue drawing seems to disappear (not completely) when viewed through the blue filter. The blue filter transmits blue and green light. The blue and green of the white paper and the blue and green of the comic drawing pass through the filter. *The two look the same through the filter. The blue seems to disappear through the blue filter.
Have students look about the room with red then the blue filter. Do they notice that reds and oranges look dark or black through the blue filter? Do they notice that blue and turquoise look dark through the red filter? Do they notice that red, orange, yellow and white all look the same through the red filter? (The red part of red, orange, yellow and white pass through the filter. That is why they all look the same. Shades of blue, turquoise and white look nearly the same through the blue filter. Green and blue from the white paper and from the blue drawing pass through the filter. They look the same. That is why the blue seems to disappear – mostly.
When the right eye looks at the 3-D drawing through the blue filter the orange portion of the picture turns black and the blue part disappears. When the left eye looks at the 3-D drawing through the red filter, the blue part of the drawing looks black and the orange part disappears. The right eye sees one black image. The left eye sees a different black image.
The two black images are in different locations on the retina of each eye. The brain brings the two images together to make a 3-D image. The secret to 3-D drawing is that each eye sees a different black image. The brain merges the two images.
Let children experiment with crayons and colored pencils two at a time (hold both colored crayons or pencils in the same hand as they draw). Have them look at their drawings through the 3-D glasses. Help students see that blue drawings look nearly black and red drawings disappear if viewed through a red or red-orange filter. Conversely orange drawings look black and blue drawings nearly disappear when viewed through a blue filter. Students usually settle on a light blue-green or pale blue crayon and an orange or red crayon (or colored pencils).
Should the blue drawing be to the left or the right of the orange (red) drawing? This will be the key to their success at 3-D drawing for perspective. Look at objects that look close up. Notice the distance between the blue on the right and the orange on the left. This gives considerable binocular disparity. The left eye looks far to the right and the right eye looks far to the left. The object looks close. Increase the distance between the two colors in the drawing and the object will look closer still. Observe the objects that look a middle distance away. The blue is to the right but very close to the orange. This is less binocular disparity. The object looks farther away. To further decrease binocular disparity, the blue moves to the left and the orange to the right. The right eye looks more directly at orange and the left eye looks more directly at blue. As the distance between the blue drawing (now on the left) and the orange drawing (on the right) increases, the binocular disparity decreases and the object looks farther and farther away.
Have students use this knowledge to create diagrams or drawings with depth.
(Courtesy of Chris Halle, LA Unified School District)
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