From a link in an IMHO fantasy thread, this link was posted to a screen shot of a flight simulator.
The grey bit of the picture appears to be in motion, is this because of the deficiency of my monitor, or an optical illusion? And if the latter, what causes it?
It’s not moving for me, but probably what’s happening is that the grey section is actually a checker of black and grey (I think), and something about your monitor is making the individual lines appear to animate.
I find it emotionally moving: the greyness of the chequerboard apron, reflecting our (“the pilots’”) despair, yet it is somehow hopeful: this dull grey expanse holds the promise of a better life just over the horizon; the clever contrast between the vanishing-point perspective, and the uncompressed chequerboard - are we here, it asks, or are we really travelling away? Have we just arrived? In birth there is death; in death, rebirth, arrival/departure - or crash? A masterpiece.
Oh OK, in reality I have a flat panel monitor, and it is definitely wobbling around.
It’s a moire effect, because the pixels are a high contrast checkerboard pattern that don’t quite line up with your monitor resolution after having been resized.
I have a flat panel monitor and I can discern no apparent motion. I agree with Sage Rat - if an image like this - with a very fine checkerboard pattern used for shading - is displayed on a CRT monitor which uses interlaced scanning, it will appear to shimmer or move because different lines of dots are alternately being displayed and they happen to be close enough to the scan line height of the monitor to make it appear as though they’re not different lines of dots, but the same line, moved.
Dunno why it would happen on a flat panel monitor unless there’s some scaling going on (a 1024 x 768 graphics card output stretched to fit a larger resolution panel, or if the flat panel monitor is actually a TV and the signal is going through part of the transfer as an analogue signal - that can cause crawly images sometimes.
Used to happen with TV newsreaders and tweed jackets, back in the 70s.
Those of you who see it moving, do you have astigmatism? I do not see it moving but sometimes my astigmatism causes me to see strange motion where there are similar patterns. When I try to read letters that are far away, for instnance, they sometimes seem to “shimmer.”
The repetitive dot pattern interacts with saccadic eye movements.
I’m not finding a description of the precise effect online, but Wolfram has a nice description of the similar Ouchi Illusion.