We keep on talking about "eye level" but what we really should be concerned with is the getting the most of the image to fall on the central (macular) region of the retina and that means we have to consider the orientation of our gaze. I, for one, do not sit erect when I am watching a movie (in the theater or at home) but recline so that my gaze is directed slightly upward. That means my central field of vision is, depending on the recline angle and the eye-to-screen distance, generally much higher than the height of my eyes as measured from the floor. The result is that we (and this is subjective and particular to my house) are most comfortable with the
bottom of the screen at physical eye-level.
Is there evidence for for your belief?
Hi Kal.
Oh boy, the number of times that graph was posted over at AVSforum as we'd chew over these issues!
You make a very good point.
However, in my post I was making the case for our eyes being centered with respect to the angle of the screen remaining. As I argued, the depth cues for any image are "correct" (as captured by the camera or created for display in VFX) only from that angle - an angle where the viewer is looking centrally at the image, at an angle parallel to the image. Once you start moving off-center to the image - sideways, above, below, you are introducing new geometrical cues (e.g. the elongating of someone's face, throwing off horizon line cues etc) that add distortion and provide further cue "I"m looking at a flat image from an angle, not a 3 dimensional image." Of course even when perfectly centered we have cues it's a two dimensional image (e.g. lack of Stereoscopy etc), but images with strong depth cues can invoke a sense of depth.
I have found that when I am adjusted so that I'm viewing a big image exactly in the center, there is a slight "click in" effect in the perception of depth and immersion. If this is the case, if you are leaning back while viewing but still filling your central macular region of sight, the last tweak would be to angle the display so it's parallel to your angle of vision. (Not that I'm suggesting it, just expressing the concept I'm talking about).
BTW, I discovered something cool about 2D images long ago when watching movies in the theaters. If I covered one eye and kept looking at the movie image, it would become more dimensional (say, over the course of 10 to 30 seconds), almost like slowly putting on 3D glasses! I can't say why for sure, but I infer that this is because the brain will take any cues it can to make sense of the reality you are seeing, so if you take away the stereoscopic cue your brain says "ok, what do I have to use to understand distance and depth here? Ah, look at all those depth, shading, horizan-line cues in front of me, THAT must be far away, this must be closer" and the 2D image starts to look more like the "normal 3D world."
I just used this trick while watching an interview on my iMac 5K computer. I noticed the image of the interviewer/interviewee was particularly sharp and dimensional in quality. It was very "realistic" except that it was a flat image. When I closed one eye the image no longer looked flat.
It became almost exactly like looking through a display at a real person talking in front of me. Uncanny!