3D used to be a technology of the future, and was once a novelty at the cinema. Now it has become common and is also available to be used in our own homes. The process behind 3D can be simple or complicated depending on who you talk to. We will try to give you the simple explanation.
We see objects in 3D every day. Our left eye captures one image, and our right eye captures another image. These images, although of the same thing, are slightly offset because of the distance between our eyes. Our brain then acknowledges the disparity between the two images, automatically fills in the difference and combines the information into one image, giving us the perception of three dimensions. In 1838, a man named Sir Charles Wheatstone named this process “Stereopsis”. It’s easy for us to know we are seeing objects in 3D in our daily life because we also have the ability to engage our sense of “touch”. Not only can we see objects in 3 dimensions, but we can move around and touch them. This satisfies our brain, confirming the fact.
The difficulty in “tricking” our brain into thinking it is seeing 3 dimensions, when staring at a flat 2 dimensional object such as a movie on a screen is where technology steps in. Technology has seen specialised rigs developed which synchronise two movie cameras precisely (often bolted) side by side filming the exact same scene. This provides the director and editor with two versions of each scene with zoom, movement, panning and everything else that match the camera beside it, yet with a slightly different position. Upon completion of the movie, the left camera’s images will be used to create a movie especially for your left eye, and the right camera for your right eye. During editing, these two films are overlayed yet remain separate from each other providing two polarised images. This is why when you’re watching a 3D movie at the cinema and you take your special glasses off you notice the film is totally burry and unwatchable.
Depending on your age, you may remember the days when 3D glasses consisted of a cardboard frame with one red and one blue lens. This now out-dated technology had one layer of film projected in red going to one eye, and the other in blue and projected to the other eye. Other colours were able to be projected also, however clarity was sacrificed and images did tend to bleed into each-other. Thankfully we’ve moved on from this.
When watching 3D at the cinema today, you will be viewing with “Polarised Glasses”. The lenses are designed to receive the left camera image in the left eye, and the right camera image in the right eye. Pretty clever hey!
The next step in 3D viewing is now 3D televisions and projectors for home use, as movies made in 3D are now being released on Blu-ray. Depending on your TV or projector you will either use “active” or “passive” glasses.
Active glasses are battery operated and controlled by a timing signal sent from your television via wireless, infrared, Bluetooth or wired cable. They work with a fast moving shutter system, which opens the left lens to send an image to your left eye, the closes it to send another signal to your right eye. This happens so rapidly that your brain merges both sides into a seamless 3 dimensional image.
Passive glasses display both pictures for both eyes at the same time. These are essentially the same type of polarised lens that you will use in the commercial cinemas. A much simpler pair of glasses, passive glasses, unlike active glasses, do not contain any electronics. Your 3D capable TV will filter the odd lines on the screen and make them visible to the left eye, and the even lines visible to the right. Without your glasses, the TV looks normal.
We can speculate about where the future of 3D viewing will go. Someday we will not need special glasses to view movies in 3D, because the televisions, projectors etc will do it all. We will probably even see personal video cameras which will allow us to create our own 3D movies. It will certainly be exciting to watch this space as it develops.
Selby stock a range of 3D capable projectors.
