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pixeldpi

Why is the visual angle equals 0.0213°

It's been said that the Visual angle = object size / object distance.

Calculation
One pixel on a device with a pixel density of 96dpi and a distance from the reader of an arm's length. For a nominal arm's length of 28 inches, the visual angle is therefore about 0.0213 degrees.

(1/96/28) = 0.00037 ≠ 0.0213



Update

Text Explanation
It is recommended that the reference pixel be the visual angle of one pixel on a device with a pixel density of 96dpi and a distance from the reader of an arm's length. For a nominal arm's length of 28 inches, the visual angle is therefore about 0.0213 degrees.

Confusion 1
Shouldn't it be 0.0213 radians?


Graphical Explanation enter image description here

Confusion 2 Shouldn't it be like that, even though the described sector should look much narrower?

enter image description here

Solution

  • The angle is expressed in radians, not in degrees. You need to convert between the two.