Archive for the ‘How 3D Works’ Category

Challenges of Mastering for Both Cinema and Home Viewing

May 26th, 2010

Stereo separation is what creates the 3D effect in images.  Offsetting the image in the left and right eye simulates what happens with your vision.  Your eyes are about 2.5 inches apart and so they see things from slightly different angles.

The problem with mastering content once for both the 8 foot experience on a 46 inch screen and the 40 foot experience on a 500 inch screen is that the scale of the separation is very different.

When you watch a movie on a big screen you process the image as a large scene which you can change your focus on various objects in the scene.  Where as on a small screen you process the whole image at once.  This makes mastering the content very different.

If an object in the left eye’s image is an 2% of the image size left of where it is in the right eye on a big screen that may work for the people in the middle of the theater but those in the front may not be able to process that as a single object.  On a small screen 2% of the image size may not even be perceived as offset.image

If you are sitting in the front row of a movie theater with your glasses on you are likely 12 feet from the screen, which is 24 feet across.  2% of the 288 inches puts 6 inches of separation between the left and right eye. The perceived depth of this object will be twice that of someone sitting in the middle of the cinema 24 feet back.  On a 46 inch screen (about 34 inches wide) at 8 feet a users gets the same amount of depth as a cinema viewer at 68 feet. (most cinemas don’t let you sit this far back from a screen of that size)

Most home viewers don’t have a cinema style set up which fills their field of view, so they get even less perceived depth.  The result is that a movie has to have slightly muted 3D to be enjoyable from a large number of positions in the theater, and home viewing needs slightly expanded 3D to create perceivable depth during viewing.

To make the matter even more complicated, those end users who do have a cinema style set up with cinema like viewing angles are going to be happiest with the Cinema version of the 3D effect, not the "Home viewing" set up that the majority of consumers would have.

How 3D Works

Psycho Visual Modeling: The Beans Don’t Move, Your Brain Moves Them

May 20th, 2010

Our brain is designed for living outdoors in a 3D world.  Seeing things in two dimensions and extracting depth is actually a trick we learned over time.  As revolutionary as perspective was in painting, the ability to give the brain cues to interpret more depth from an image has never really been applied to video or film.  It was always assumed that to make good 3D you needed to have two camera’s, or sophisticated motion interpretation so that a computer could calculate the depth from parallax.  In much the same was as the beans below appear to move even though they are not, given the right visual cues your brain can make any 2D Image 3D, and because your brain is doing the work it very rarely will get it wrong.

Moving Beans Optical Illusion

How 3D Works