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Perspective

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fwk
1254686.  Wed Oct 11, 2017 10:12 am Reply with quote

A forced perspective is a technique that changes the perception of scale, distance and orientation for an observer in architecture, art, photography and filmmaking. For example, the scene has a larger film set, smaller props, and an actor standing closer to the camera than the others. This makes one character look larger than the actor otherwise would in real life. This technique was seen in the films from the Harry Potter and Lord of the Rings franchises.

A very popular forced perspective photograph is the 'giant' bracing the Tower of Pisa, or pushing it over. However, another way of using a forced perspective is to change the spectator's sense of orientation. For example, placing the camera on the ground and taking a picture of someone crawling as though they are climbing a cliff face. Props can also amplify this effect like the person might be wearing climbing gear or their belongings are on the top of the 'cliff'.

Video presents a much greater challenge as shadows, unexpected movement of objects, or actors making mistakes can break the illusion. Every camera movement, set design, and lighting needs to be calculated and meticulously fine tuned. One particularly difficult problem is parallax.

Look directly at an object in the distance. Point your finger at the sky and hold it one or two inches away from your nose. Look straight ahead and you should see your finger doubled. When you close your right eye, your finger will be on the right side of the object, and if you close your left eye, your finger will be on the left side of the object. Objects closer to a moving camera seems to move its apparent position more than objects further away. A way to mitigate this is rotating the camera about the no-parallax-point, the lens. This should minimise objects moving at different rates. For panning shots, the movement of the camera needs to be choreographed with parts of the set. This can be done practically or digitally.

Buildings have been designed with forced perspective techniques for centuries to look pleasing to the eye. Without it, there would be visual distortions. Straight lines could look bowed or bent and symmetrical features may look asymmetrical. The corner columns of the Parthenon, for example, are thicker than the pillars in the middle. They are spaced differently to give the perception of symmetry. Each column also bows out in the middle so that they look more robust, as a straight column, from a spectators perspective, would look more tapered and slender.

The Statue of Liberty was designed to be seen from the ground and the proportions were adjusted to be wider at the top to compensate for the visual distortion. This caused problems for the filming of the movie Ghostbusters 2, as replicas of the statue needed to undo the forced perspective scaling of the real statue to avoid looking top heavy. Disney theme parks, in contrast, have some buildings that get narrower with height, like the castles for example. Forced perspective design and smaller bricks used higher up the building makes it look taller and bigger.

A perspective-control lens, also known as a tilt-shift lens, is used to take photographs of buildings without distorting the angles. It allows the film or sensor to stay parallel to the wall of the building, minimising the tapering effect from pitching the camera up to get the whole building in frame. A tilt-shift lens can also be used to photograph an angled plane, like a sloping landscape, and keep all of the features in focus without reducing the aperture, which would dim the photograph. The lens can also be used to give a photograph a very shallow depth of field. This makes the subject look like miniatures, as though the scene was magnified using a macro lens.

Scientists have observed forced perspective techniques used in nature. Bower birds from Australia and New Guinea make an avenue from stones. Larger stones are placed near the courtyard or stage where the male performs and smaller stones are placed nearer to where a female would stand. The effect is that it makes the avenue look longer and it seems that the stronger the effect, the more successful the male will be. It is not currently known whether the birds are aware of the forced perspective effect or whether it is just trial and error.

https://en.wikipedia.org/wiki/Forced_perspective
https://fronteffects.wordpress.com/2014/06/24/forced-perspective-theory-and-practice/
https://en.m.wikipedia.org/wiki/Parallax
http://www.architecturerevived.com/how-greek-temples-correct-visual-distortion/
https://en.m.wikipedia.org/wiki/Tilt-shift_photography
http://www.cambridgeincolour.com/tutorials/tilt-shift-lenses1.htm
http://www.cambridgeincolour.com/tutorials/tilt-shift-lenses2.htm
http://www.cambridgeincolour.com/tutorials/macro-lenses.htm
http://blogs.discovermagazine.com/notrocketscience/2012/01/19/male-bowerbirds-use-forced-perspective-architecture-to-get-more-sex/

 
crissdee
1254721.  Wed Oct 11, 2017 11:54 am Reply with quote

fwk wrote:
Buildings have been designed with forced perspective techniques for centuries to look pleasing to the eye. Without it, there would be visual distortions. Straight lines could look bowed or bent and symmetrical features may look asymmetrical. The corner columns of the Parthenon, for example, are thicker than the pillars in the middle. They are spaced differently to give the perception of symmetry. Each column also bows out in the middle so that they look more robust, as a straight column, from a spectators perspective, would look more tapered and slender.


Rolls-Royce radiator grilles always used to be made in a similar fashion, making the grille bars thicker in the middle to make them look straight, and making the "flat" surfaces slightly convex to counteract the high polish which makes them look dished. Old ones have the name of the man who made them inside, so that if they are damaged they can go back to him for repair, as it is/was all done by hand with no measurements involved.

 
fwk
1254738.  Wed Oct 11, 2017 1:16 pm Reply with quote

This reminds me of the Apollo spacesuits. The suits needed to be airtight so the seamstresses needed to be careful not to leave any pins or needles in the suit as they were sewing. When they did find a pin:
Ellie Foraker, seamstress wrote:
"I showed her the pin and I said, "You see this? It just came out of that garment that you sewed. So I'm gonna show you what a pin will do" and I stuck her in the butt. And I said, "Do you think you will remember the next time you leave a straight pin in something?" She said, "Yes ma'am"."


http://backstory.blogs.cnn.com/2011/10/27/from-bras-to-spacesuits-the-untold-story-of-apollo-11/

 
'yorz
1254747.  Wed Oct 11, 2017 1:38 pm Reply with quote

Somebody had to post this.

 
Bondee
1254755.  Wed Oct 11, 2017 2:17 pm Reply with quote

fwk wrote:
For example, placing the camera on the ground and taking a picture of someone crawling as though they are climbing a cliff face.


Holy human flies!

A device that Kevin Smith put to good use in the animated series of Clerks...

Why are we walking like this?

 

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