WEBVTT
Kind: captions
Language: en

1
00:00:00.110 --> 00:00:02.010
This video is in 3D.

2
00:00:02.010 --> 00:00:03.429
Really, it is.

3
00:00:03.429 --> 00:00:08.060
If you get a pair of sunglasses and you just
cover your right eye,

4
00:00:08.060 --> 00:00:09.589
you should see a 3D effect.

5
00:00:09.589 --> 00:00:12.712
I mean, assuming both your eyes work, obviously,
sorry if they don't.

6
00:00:12.712 --> 00:00:16.330
The effect will work best
on a big, bright screen,

7
00:00:16.330 --> 00:00:18.720
in a bright room, wearing dark sunglasses,

8
00:00:18.720 --> 00:00:20.940
and if your device is playing this
at a high frame rate.

9
00:00:20.940 --> 00:00:26.270
If you're just kinda lying in bed squinting and
holding your phone out, it probably won't work.

10
00:00:26.270 --> 00:00:27.730
Also, you look ridiculous.

11
00:00:27.730 --> 00:00:32.029
Normal 3D video works by sending a different
picture to each eye:

12
00:00:32.029 --> 00:00:35.150
those two simultaneous images,
one for the left eye, one for the right,

13
00:00:35.150 --> 00:00:36.790
are called a stereo pair,

14
00:00:36.790 --> 00:00:40.210
and they simulate what you would see with
two eyes.

15
00:00:40.210 --> 00:00:44.200
So you display two images on the same screen
at the same time,

16
00:00:44.200 --> 00:00:46.820
and then you use filters to show only one
to each eye.

17
00:00:46.820 --> 00:00:50.020
And that might be using a red and blue image
and coloured filters,

18
00:00:50.020 --> 00:00:54.000
or weird tech-glasses where each lens goes
opaque 60 times a second,

19
00:00:54.000 --> 00:00:58.790
or in a modern cinema, glasses that filter
using polarised light.

20
00:00:58.790 --> 00:01:03.460
But because there have to be two separate
images on the same screen at the same time,

21
00:01:03.460 --> 00:01:07.470
for anyone not wearing those glasses, it's
a confusing mess.

22
00:01:07.470 --> 00:01:12.570
But this video here works as a
normal 2D video as well, at the same time,

23
00:01:12.570 --> 00:01:15.670
and the reason is something called
the Pulfrich effect,

24
00:01:15.670 --> 00:01:21.450
named after Carl Pulfrich, the German optometrist
who first documented it in the early 20th century.

25
00:01:21.450 --> 00:01:25.810
Your eyes and brain take a little bit longer
to process dark images than light ones.

26
00:01:25.810 --> 00:01:28.960
Now, exactly how long depends on the relative
brightness of the images,

27
00:01:28.960 --> 00:01:32.130
but it's usually roughly around the length
of one frame of video,

28
00:01:32.130 --> 00:01:37.210
which is pretty useful for something first
noted nearly a century ago.

29
00:01:37.210 --> 00:01:41.979
If you put dark sunglasses over your right eye,
then the image from that eye

30
00:01:41.979 --> 00:01:45.640
will get delayed by about one frame
on its way through your brain.

31
00:01:45.640 --> 00:01:51.950
So you end up seeing two different images,
one frame apart in time.

32
00:01:51.950 --> 00:01:54.400
But that's not enough to create a stereo pair
on its own.

33
00:01:54.400 --> 00:02:00.350
The other ingredient is the bizarre, nausea-inducing
moving camera.

34
00:02:00.350 --> 00:02:02.720
Because that camera has
constantly been in motion,

35
00:02:02.720 --> 00:02:06.300
your right eye has been lagging behind
by about one frame,

36
00:02:06.300 --> 00:02:10.060
just as if there was a second camera
just to the right of that one,

37
00:02:10.060 --> 00:02:12.840
giving a separate stereo image
to your right eye.

38
00:02:12.840 --> 00:02:13.970
Now that's a stereo pair.

39
00:02:13.970 --> 00:02:17.970
So if we stop the camera rotating, the effect
disappears,

40
00:02:17.970 --> 00:02:20.380
and everyone can take a breath.

41
00:02:20.380 --> 00:02:23.810
That also works by moving
the objects in the frame.

42
00:02:23.810 --> 00:02:27.670
That's why, earlier, the cutaways I used had
constantly moving backgrounds.

43
00:02:27.670 --> 00:02:30.340
And sure, it's not perfect 3D.

44
00:02:30.340 --> 00:02:32.379
But your brain fills in the gaps.

45
00:02:32.379 --> 00:02:35.800
The Pulfrich Effect works well enough that
it's been used for TV shows occasionally,

46
00:02:35.800 --> 00:02:37.020
and for a couple of video games.

47
00:02:37.020 --> 00:02:41.580
In the 90s, the BBC had a special
series of 3D shows for a charity telethon,

48
00:02:41.580 --> 00:02:44.200
including one of the worst
Doctor Who productions ever made.

49
00:02:44.200 --> 00:02:45.739
- "Who's that terrible woman?!"

50
00:02:45.739 --> 00:02:48.810
But if you look at it, in every shot,

51
00:02:48.810 --> 00:02:51.310
something in the foreground
moves left to right,

52
00:02:51.310 --> 00:02:54.330
and something in the background moves
right to left.

53
00:02:54.330 --> 00:02:55.330
Constantly.

54
00:02:55.330 --> 00:02:59.819
So because every camera shot has to be carefully
planned, and in constant motion,

55
00:02:59.819 --> 00:03:03.200
you won't see Pulfrich effect videos in the
cinema any time soon.

56
00:03:03.200 --> 00:03:08.030
It isn't practical for anything more than
quick, short gimmicks.

57
00:03:08.030 --> 00:03:10.569
Gimmicks like this video.

58
00:03:10.569 --> 00:03:12.180
You can take the sunglasses off now.

59
00:03:17.180 --> 00:03:19.540
One take!  One take!

60
00:03:26.700 --> 00:03:29.160
Wait, did I go the right way there?