What is it about 1570 movies that make it almost like being there? (and often, a lot more comfortably and safely than actually being there, as in a Proton rocket launch or at a Fire in Kuwait). There are many theories — here are some of my favorites:

Viewing Angles

Our Quest for Reality begins by trying to approximate the very wide viewing angles we use every single day in navigating about in the real world. The importance of peripheral vision is well known to psychologists and equipment designers alike. As you can see from the illustration, our eyes collect data over such a wide range of angles (over 120 degrees horizontal) that any movie system with small viewing angles is going to be less "immersive" than our wider 1570 experiences. Hence our decision to film and project with wide angle lenses, and to seat the audience relatively close to the screen. The wider viewing pyramid extending from the eyes to the screen is even more important in 3D. Seeing wide is perhaps the most important cue to that sense of "we are there — in the picture". The ability to look down as well as up is also important, and many theatres are now copying our style of stadium seating. To paraphrase my friend and film theorist/director Ben Shedd, we explode the frame and the frame is gone — frameless pictures. We look out of the screen filling almost the entire front wall of the theatre as if the theatre has been sliced open giving us an open window on the world! And in Imax dome or Imax dome 3D, there simply is no wall!

Resolution and format size

In this world of trying to stretch dimes into dollars, compress man-days of work into man-hours, and compress gigabytes of data on our hard drives into megabytes, it is still difficult to achieve the same sort of fine-grained visual reality we enjoy as we look out at the world about us. A reasonable figure of merit for human visual acuity of high contrast subjects is from 1 to 3 minutes of arc (1/60^th to 1/20^th of a degree). Hence in a 120 degree wide horizontal peripheral field of view we can resolve about 120 x (60 to 20) = 7200 to 2400 discrete points, in the real world, without even turning our head. Our large 1570 film format of 69.6 mm wide by 48.5 mm high can capture and present almost this full amount of information. I have shot 15/65 lens tests clearly resolving 44 line pairs per mm, which would yield 44 x 2 x 69.6 = 6,125 pixels horizontal — close but not quite equal to reality. Also we routinely film record CGI images at 4096 x 3002 pixel resolution , and with the new laser recorder will go even higher — up to 8K potentially. Even if you don’t like or follow my math, suffice it to say that higher resolution pictures simply give a closer approximation to reality. Even 15/70 is not yet eye-limited in resolution, but still limited by film and projection! Smaller formats have less information content, period, no matter how they cut, dice, stretch it or sell it — digital magic notwithstanding. It is format information content that matters most, not simply screen size.

Brightness and Contrast

While our 1570 movies are still a far, far cry from matching the typical brightness of real world scenes outside, our eyes are pretty adaptable to changes in brightness so they can function in hazy dusk as well as at high noon in glaring sunlight. We continue to work hard at improving brightness of movies, towards the current limit of how much light you can pump though a film emulsion without melting or fading the image. Obviously both brightness and image contrast are affected by screen and theatre design, and there are tradeoffs that are made between seating capacity and brightness which perhaps have been pushed too hard at times. Nevertheless, having a larger format with more image area means you can pump through more light without film damage, all other things being equal. And the darker black areas may appear more black than a smaller film area or electronic projector with lower contrast ratios than film. Good blacks are important to our sense of "being there", whether the images are shown from film or other sources.

Steadiness/Image stability

When we hold our heads and eyes still the real world doesn’t jump around too much, and neither should our movies jump or weave under similar conditions. A large 1570 film format perforation sitting on fixed registration pins has many times the steadiness of smaller format projectors registered on moving parts like sprocket teeth driven by cams or motors. Also, as you can well imagine, if two films have the same unsteadiness in the projector gate but one is magnified twice as much to fill the same size screen as 1570, the shake of the film will also be magnified proportionally. Big frames are easier and more forgiving — I like to say they have "head room" or tolerance to errors from Mr. Murphy. Focus stability is also easier to attain with a field flattener and vacuum holding the film (without breathing) than systems with film floating in the breeze so to speak. Pictures should stay in focus, just as our eyes lock in and focus on real objects.

Colour & Texture

How subtle and beautiful are the millions of colours our eyes can detect and differentiate in the real world — the shifts in shade of a sunset from azure to red or the richness of texture and pattern in the sheen of hair or foliage! I don’t know how to explain this effect exactly, but one of the biggest differences we see in testing and comparing film, video and digital formats, projectors or special effects blowups is their ability to capture subtleties of colour and texture. Taken to an extreme, a super 8 film blown up to 1570 may capture an underexposed wooden floor as more-or-less a single grainy mass of the same brown tone, or perhaps a few posterized tones. A 35mm blowup may have dozens or hundreds of clearly separated tones between the boards in the floor, from orange- brown to dark walnut tones. But a 1570 original neg with no blowup whatsoever has thousands of beautiful distinct tones and textures in each strand of the wood grain that simply were not visible at all in the smaller formats — more of that "headroom" I was talking about. The real world is almost infinitely textured, when seen at any viewing range (like fractals) and it excites a multitude of colour excitation responses in our eyes. Film can easily capture 14 bits linear, or 10 bits log per colour even though we often restrict output dynamic range for synthetic CGI shots. Better colour and finer textures give a better sense of "being there". Generally film still beats electronic displays here.

Bandwidth

How fast does information actually flow to our brain from our eyes as they gaze out on the real world, assuming we bypass for the moment philosophical discussions about what is "real"? Well, this is a lot tougher to calculate, because our eyes dart and look around building up our model of the outside world using the hi-res foveal area largely that is engaged as you read each letter on this page. But the rate at which this information flows is surely important, as anyone who has watched a low bandwidth internet movie or videoconference can attest. With a typical Imax 3D CGI movie running 24 frames per second, you are seeing 4096 x 3002 pixels x 24 bits colour/pixel or around 295,108,608 bits on every frame. With 8 bits per byte each 1570 frame is around 36.9 Megabytes. Now if we run both eyes (L&R) at 24 frames per second we are seeing around 36.9 x 24 x 2 = 1,771 Megabytes or roughly 1.8 Gigabytes per second! That sure fills up your hard drive quickly, doesn’t it? As nobody yet can honestly say watching an Imax movie is as smooth and sharp as watching the outside world, I postulate that our eyes at least can easily accept over 2 gigabytes per second of information. Now if only my old brain could read email that fast!…..

High fidelity sound

There are sonic analogies to all of the above visual factors that help us in our Quest for Reality in 1570 films shown in our theatres. I don’t have space to elaborate but I think it is self-evident that the latest innovations from Sonics and sound mixers approximate our experience of hearing in the real world very closely indeed, and elevate music and effects to a high art. PSE can create spatial effects of proximity that are stunningly realistic in effect (anyone here ever had the Sonic’s haircut?)

A dream

As you can see from the above our attempts to make the audience "be there" in space, on top of mount Everest or deep in the sea swimming with Howard Hall’s amazing swirling spheres of fish is far from over, and does not result from technical excellence alone. Obviously the artistic skills and talents of amazing filmmakers are what ultimately brings any illusion to life. In this collaborative art of film the closest technically I have seen to reality was a brief test we did together with the National Film Board of Canada of 48 fps 3D, viewed here in our R&D high bay several years ago. The information flow of those images easily exceeded 4 Gigabytes per second, and were stunningly smooth and realistic. I dream that someday a whole film might be made for such a system at an Expo or Special Event — even though it would be very difficult and expensive. From an engineering point of view at least — I can’t imagine getting much closer in our Quest for Reality.