Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Ray tracing, regarding Turner Whitted's original paper

  1. Dec 16, 2013 #1
    As many of you may know, ray tracing was first introduced by Turner Whitted in 1979 in a paper titled "An improved illumination model for shaded display" (can be found on ACM digital library).

    On the 2nd page, in part 2 (Improved Model) there are a number of fairly simple vector calculations, unfortunately I can't understand what is vector V' (please refer to the attached screenshot), and why is it scaled by | V . N | ... I would like to ask for your thoughts on this :)

    Thanks !

    P.S.: unfortunately I can't attach the paper to my post, it is copyrighted by ACM and I think it would be illegal to do so.

    EDIT: found a link to the paper from Drexel University here
     

    Attached Files:

  2. jcsd
  3. Dec 16, 2013 #2

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    The diagram shows you the vector (N + V'), as the "horizontal" dotted line ending at the top of the N vector.

    So V' is the third side of the triangle with the other two sides N and (N+V'). Ini other words, V' is the V vector scaled to be the same "vertical height" as N.

    Earller N was defined as the unit vector (i.e. its length=1) normal to the surface.

    So |V.N| is the length of V, times the cosine of the angle between V and N.
     
  4. Dec 16, 2013 #3
    Hi AlephZero,

    Thank you so much for your reply, I appreciate it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Ray tracing, regarding Turner Whitted's original paper
  1. Trace operator (Replies: 1)

  2. Trace and derivatives (Replies: 5)

  3. Rank and Trace (Replies: 3)

  4. Trace and endomorphism (Replies: 1)

  5. Determinant and trace (Replies: 2)

Loading...