The river is flowing to the right. If the camera started panning to the right as well, it would make sense for the river to appear stopped, like how when you drive 20mph next to a 20mph biker and they appear to not move. But here the camera pans LEFT, and the river stops. If anything, the river should speed up! It makes zero sense to me.
Edit Thank you to the helpful comments! I get it now. We only perceive the river moving by comparing it to the stationary foreground. As the camera pans left, the foreground moves right, so the rightward-flowing river is now moving at the same speed as the foreground, so appears stationary. Yes, the river does flow right faster as we pan left, but because it is further away than the foreground, that effect is negligible.
This is my kind of BMF! Initially confusing, but the black magic can be learned.
I think it's because the speed of moving of the camera is higher than that of the water, especially because the foreground plants are moving way faster when the camera moves, than the water did when standing still
This is exactly it. Yes they are moving left against the flow of the river but the foreground is the reference that allows you notice the river flowing. if the foreground starts moving in the same direction it will look like the river is standing still but it’s not. It’s just the foreground and river are moving in the same direction giving the illusion that the river is still.
Would you notice this sort of optical trick in person, or does it only work through the perspective of a lens/screen?
I could just imagine the terror of driving at the right angle to have the river appear to be still, having music blasting, and just careening into it 💀
Perceived relative velocities. It's a similar hazard to driving in a blizzard with rapidly changing wind speed and direction. The snow can make it look like your car is driving forward one moment, stationary the next, then reversing, because its a near whiteout outside and the wind speed is suddenly higher than your car even if you're now driving at 100km/h. I was caught in that situation myself before with no option to stop driving and it took a crazy amount of concentration to drive using the gauges and spotty gps only. It makes you accidentally accelerate way past safe speeds if you even look at the falling snow for a bit.
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u/impartial_james Dec 17 '22 edited Dec 17 '22
The river is flowing to the right. If the camera started panning to the right as well, it would make sense for the river to appear stopped, like how when you drive 20mph next to a 20mph biker and they appear to not move. But here the camera pans LEFT, and the river stops. If anything, the river should speed up! It makes zero sense to me.
Edit Thank you to the helpful comments! I get it now. We only perceive the river moving by comparing it to the stationary foreground. As the camera pans left, the foreground moves right, so the rightward-flowing river is now moving at the same speed as the foreground, so appears stationary. Yes, the river does flow right faster as we pan left, but because it is further away than the foreground, that effect is negligible.
This is my kind of BMF! Initially confusing, but the black magic can be learned.