DIR Return Create A Forum - Home
       ---------------------------------------------------------
       BPCForum
  HTML https://bpc.createaforum.com
       ---------------------------------------------------------
       *****************************************************
   DIR Return to: 3D Workshop
       *****************************************************
       #Post#: 66--------------------------------------------------
       Understanding 3D or Stereo Images
   DIR By: Huffman
       Date: October 1, 2013, 1:47 pm
       ---------------------------------------------------------
       The reason we see “depth” is that our eyes see a given scene
       from two different viewpoints.  When our brain combines the
       scene as represented by our two eyes, it is capable of
       estimating the depth of nearly the entire field of view.
       Look at finger about 12” from your face using only one eye.
       Now switch eyes!  Watch my eyes as I “focus” on my finger.  The
       distance between my eyes and the angle allows my brain to
       accurately estimate the distance to my finger.   This is how
       “rangefinders” work as well—using simple trigonometry.
       Most of our depth perception is due to “binocular disparity”—the
       slight differences in a scene due to the two viewpoints.
       This brings up one important observation.  A 3D stereo image can
       have more or less “depth” depending on how the image was
       constructed, and on the inter-ocular distance of the viewer.
       There are other depth cues that go into a stereo image, for
       example focus and distance fading.
       There are numerous ways to present and see 3D images.   The
       easiest way for most casual users is the use of an anaglyph
       image.  The two images (left and right) are viewed through
       glasses with colored filters that block the left eye image from
       the right eye, and the right eye image from the left eye.
       Without the glasses the photo has red and green “ghosts”, but
       these are generally not visible if the colors of the print and
       the glasses are properly matched.
       A similar technique is to use polarizing glasses and two
       projections so that each eye sees only the correct image.
       Notice that with either anaglyph or polarizing techniques, the
       depth can be reversed by reversing the glasses.
       One of the best techniques is to use “shuttered” glasses that
       turn on or off the left and right images on the monitor while
       simultaneously blanking the left or right image with the
       glasses.
       Most people are familiar with the “Holmes” viewer.
       Note that all of the options mentions thus far assume “normal”
       vision.  Some 15% (according to some sources) of individuals in
       a study had difficulty seeing in 3D, even with what was
       considered normal vision.
       For this last group there is still one technique that can be
       used—a gif animation that rapidly switches from the left eye to
       the right eye.
       *****************************************************
       Page 1 of 1