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skytiger

What is shining?

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In this picture of the sun, which is "shining", you can see many "radial streaks"
What is the name of this phenomenon? What causes it?
I believe it (like lens flares) is created inside the eye / camera / lens
because if I am wearing glasses they are much larger ...
I can't find any mention of it on the Internet!

800px-The_sun1.jpg

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I've heard it referred to as "temporal glare" with respect to computer graphics, though I don't know if that is the proper term for the physical phenomena. The explanations I read said it was due to particles in the vitreous humour of the eye.

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The explanations I read said it was due to particles in the vitreous humour of the eye.


Particles in the vitreous humour, imperfections in the lens of the eye or the camera, basically anything which can distort the flow of light; the pattern depends on the imperfection.

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Lens Flare is actually a combination of several different optical phenomena that occur because of the way lenses work.

Typically its either stray light that's entered the light gathering device from an odd angle or bright light from the scene that has been reflected/refracted back and forth inside from the front or back surface of the lens(es). These reflections can be quite sensitive to imperfections in the lens geometry or dust and atmospheric factors, and produce the differences you're seeing. I'm guessing the streaks are caused by light hitting the extreme edges of the lens.

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The words "glare" / "bloom" / "flare" are often used to describe the same categories of effects -- ones that occur in the eye/lens rather than in the air.
However, "glare" is also sometimes used to describe a specular reflection...
Some useful terms might be: "bloom" / "lens flare" / "lens blur" / "shape blur" / "bokeh".

An easy way to tell if a phenomenon occurs in the air or in the eye/lens, is to simply place your hand between your eye and the light source. If the effect is still there when the light-source is occluded from your view, then the effect is ocuring in the atmosphere. If the effect disappears when the light-source is occluded, then the effect is ocuring in your eye.

e.g. haze or sun-dogs occur in the atmosphere, so hiding the sun behind your hand will not hide the "glowing effect", however the streaks and double-images in your first post are caused by imperfections in the lens system, so hiding the sun would also hide those effects.
To my human eye they are completely different, as I get streaks and not flares (when I squint at a torch)
That's because your eye is constructed differently than a camera lens, and doesn't contain the multiple layers of glass required to create inter-reflected flares wink.png
I've only skimmed that paper a few times, but I'd guess that you could use their method to simulate a human eye as well as the different types of camera lens that they demonstrate, provided you had enough information on the geometry and types of materials used in its construction.

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I've always found it hilarious that people find it necessary to implement lens flares in games, particularly FPS's. The implication being that in first person mode the eye of the player as represented in the game is an actual camera. 3rd person perspective or cut-scenes are a different matter though.

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