If the character is standing vertically, there is no ambiguity as to these two tags. However, if the character is lying, or, more rarely, the character is upside-down, the usage of these tags is not clear to me.
Consider post #2183268. Relative to the ground, the imaginary camera is not facing up, but rather forth (even with a slight down-tilt), so then it shouldn't be tagged from_below, right? But, at the same time, relatively to the character, we are looking at them from their relative below. If we didn't have the clues to tell us that the character is lying on their back, it could be easy to assume that it's a case of from_below.
Consider, to illustrate the above, post #3868064. Is the character lying on their back? Or are they awkwardly floating/squatting above the viewer? There are no context clues to clarify this, so what do you think.
Another side of the problem are upside-down characters. Consider post #6883080. The character is upside down, and we are looking from above. Though, relative to their body, we are looking from below. So is this really a from_above? Also is this an upskirt, if we're not even looking up the skirt? Same question for poses like post #7077670.
And, lastly, there is ambiguity for cases where the character is technically horizontal, by the viewer angle is such that, relative to the character, we're looking at them from their relative "above". For example, post #4290146 - should it be a from_above, or not really?
To conclude this post, a quick disclaimer: I didn't post this as part of topic #12251, as the aim here is to make the meaning of from_above and from_below tags more specific, and consequently make a wiki edit, rather than figure out how to tag those specific images. The image posts provided here are just examples to illustrate my point, rather than specifically the main foal of the discussion. Thank you.
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