.. title: CG Class 3, Wed 2019-09-04
.. slug: class03
.. date: 2019-09-04
.. tags: class
.. category: 
.. link: 
.. description: 
.. type: text

.. sectnum::
.. contents:: Table of contents


Yesterday's program demos
-------------------------

#. I ssh'ed from my linux laptop to rcs.rpi.edu, which is a linux machine.

#. My RCS copy of the textbook files is at ~frankwr/public_html/ECSE-4750 .

#. The URL is https://rpi.edu/~frankwr/ECSE-4750/ .   

#. square.html and square.js are from Chapter 3.



Accessing RCS files from non-RPI computer, ctd
----------------------------------------------

#. FileZilla for Windows
#. http://dotcio.rpi.edu/services/file-services/mapping-network-drive-using-secureftp
#. http://dotcio.rpi.edu/services/accounts-identity/rcs-accounts/connecting-your-rcs-home-directory
#.   http://dotcio.rpi.edu/services/file-services/mapping-network-drive-rcs-using-openafs-client

Today's material
----------------
     
#.   `Serpinski gasket programs <https://wrf.ecse.rpi.edu/Teaching/graphics/SEVENTH_EDITION/CODE/02/>`_ showing more complicated WebGL.
   
#. Extra material on colors

   #. Tetrachromacy

      Some women have 2 slightly different types of green cones in their
      retina.  They see 4 primary colors.

   #. Metamers

      Different colors (either emitted or reflected) with quite different
      spectral distributions can appear perceptually identical.  With reflected
      surfaces, this depends on what light is illuminating them.  Two surfaces
      might appear identical under noon sunlight but quite different under
      incandescent lighting.

   #. CIE chromaticity diagram

      This maps spectral colors into a human perceptual
      coordinate system.  Use it to determine what one color a
      mixture of colors will appear to be.  The curve of pure
      spectral colors was determined experimentally.

      #. More info: http://wikipedia.org/wiki/CIE_xyY .

      #. Purple is not a spectral color.

   #. Color video standards: NTSC, SECAM, etc

   #. My enrichment note on `NTSC And Other TV Formats <https://wrf.ecse.rpi.edu/pmwiki/Research/NTSCAndOtherTV Formats>`_.   NTSC, the American analog TV standard, is now getting obsolete.  However it was a beautiful example of engineering design.   First B&W TV was invented.   Then color  was added in a way that was upward compatible, downward compatible, and used no more bandwidth.

   #. Failed ideas:  mechanical color TV.   `<http://en.wikipedia.org/wiki/Mechanical_television>`_ (enrichment).

   #. Additive vs subtractive colors.

      #. http://www.physicsclassroom.com/Physics-Interactives/Light-and-Color/RGB-Color-Addition/RGB-Color-Addition-Interactive

   #. Sensitivity curves of the 3 types of cones vs wavelength.

      #. http://i.stack.imgur.com/5snTb.png

   #. Material reflectivity vs wavelength.

   #. Incoming light intensity vs wavelength.

   #. Retina is a neural net - Mach band effect.    When one cone is brightly lit, it inhibits its neighbors from firing so easily.   This acts like a high frequency filter, to emphasize small details in the scene.   *Note: the details of how this works are uncertain.*

   #. I'll do in class:

      Week 2, set 1, Models and architectures
 

Homeworks
---------

#. I'm using LMS only for submitting homework and recording
   grades.  The text of the assignments will be only on the
   course page.

   The reason is that LMS is really badly designed.  E.g.,
   entering a formula into its spreadsheet requires clicking on a
   menu (you cannot type the formula), and the formula cannot be
   edited.