Welcome back to the Full Dome Saga. For those of you just checking in, last week’s article can be found here Part 1.
So what is a 4k production? It’s a full dome movie that takes four Kyras to produce it, a 4K production…..
Jokes aside… 4k is short for 4,000 pixels.
Movies everywhere are made up of individual images called frames, played back at high speeds to simulate motion. The higher the frame rate, the smoother the motion and the higher perception of realism. Low frame rates cause motion to appear jerky and the picture to flicker. Think back on early films from the 1930s and 1940s, or funny internet GIFs of today.
When we go to a movie theater and they advertise that they are a 4k cinema, what they really mean is that their movie is 4,000 pixels wide and 2,000 pixels tall (roughly) because movies are rectangular (your HD tv at home is 1920×1080 pixels). So each frame is approximately 4,000 pixels across and 2,000 pixels tall.
Generally, movie theaters run at 24 frames per second. Peter Jackson made headlines when he offered The Hobbit at 48 frames per second (gasp!). Many still argue that high frame rates for live action films on flat screens produce too much realism for the audience to enjoy. Personally I enjoyed they hyper realism of The Hobbit at 48 fps, but that’s just me.
Movies like The Hobbit push the envelope for current technology. Capturing live action at high resolutions and high frame rates (then double this for two cameras if you’re making a 3D movie), require sophisticated and expensive camera equipment. The Red Epic (used to film The Hobbit and other recent blockbusters) is advertised as a 4k camera. I am often asked, why don’t you planetarians use that to get 4k live action footage for your dome? Not so fast son….
Here in the planetarium things are a bit different. Rather than a rectangular screen in front of you, there is a hemispherical screen that surrounds you. The movie is in front of you, next to you, above you, and behind you. 4k in the planetarium world means each frame is 4,000 by 4,000 pixels (a square rather than a rectangle) twice the number of pixels per frame.
Many digital planetaria run full dome movies at 30 frames per second, but producers are beginning to push the envelope. If you thought The Hobbit at 48fps was crazy, some digital planetaria offer full dome movies at 60 fps. The high frame rate applied to CG graphics creates that extra degree of smoothness and realism in the motion of objects on the dome. Stay tuned, as we have been dabbling in this a bit ourselves here at LASM!
The planetarium dome is a larger surface that surrounds the audience, unlike a traditional movie screen. Therefore motion is amplified on a dome screen. For this reason planetarium shows are edited with longer cuts than traditional movies and TV content, camera movement is slower, and objects move slower. Movement that is fast and somewhat jerky on a flat screen will look even more so on a domed screen. High frame rate smoothes the motion, resulting in a more realistic experience.
Why are most full dome movies CGI you ask? Come back next week for The Full Dome Saga PT3 where we will investigate the ins and outs of Live Action vs CGI production for the dome…..