visualpython-users

[Visualpython-users] redblue stereo

[Bruce S. <bas...@un...>]

Actually already in the new version there exist the options scene.stereo 
= 'redblue' (and also scene.stereo = 'redcyan'), intended to make stereo 
images viewable with simple red/blue glasses (red over the left eye). 
For redblue to work the scene has to be grayscale, not color, and 
therein lies a design issue, because there is more than one way to 
convert colors to grayscale, and the conversion depends somewhat on 
context. In order to enable lots of people to participate in the 
discussion of what conversion (or conversion options, plural) is/are 
appropriate, there is a grayscale conversion routine now available in 
the "Contributed programs" section of http://vpython.org.

You can run it directly (it has a test scene in it), or you can say

from visual import *
from grayscale import *

scene.stereo = 'redblue' # or 'redcyan'
# make a color scene
grayscale(scene)
# do animation, etc. in 3D using red-blue glasses

See the comments in the program for more about the issues. Or maybe Hugh 
Fisher or John Zelle will offer a tutorial here.

Bruce Sherwood

[Visualpython-users] redblue stereo

[Bruce S. <bas...@un...>]

As you know, John Zelle recently contributed code to support 'active' 
stereo (with shutter glasses) and 'passive' stereo (the two views are 
sent to two computer projectors which place polarized right-eye and 
left-eye views on a screen, to be viewed with polarized glasses). He 
also put hooks into the code to support 'redblue', the kind of stereo 
which one views with cheap red-blue glasses. However, the implementation 
was incomplete in that it required that you convert all object colors to 
grayscale for it to work. I've completed the implementation by doing the 
grayscale conversion automatically. If you print some object.color, you 
won't see any change; the conversion is done internally before 
displaying in red or blue.

So you can now say scene.stereo = 'redblue' (or 'redcyan' or 
'yellowblue') and get stereo with no special computer equipment. There 
is a new Windows installer available at http://vpython.org. Linux/Unix 
installer should follow in a day or two.

The grayscale conversion is this:

   s = ( .299 * r**GAMMA + .587 * g**GAMMA + .114 * b**GAMMA ) ** (1/GAMMA)
   color = (s,s,s)

This makes different colors show up as different grays, which is 
desirable. But notice that if the original colors were red or blue, the 
resulting gray will be rather dim. To get a brighter object in redblue 
stereo, use white as the original color.

I've just ordered some glasses from 
http://www.tedpella.com/photo_html/stereo.htm. A box of 10 red-blue 
glasses is $4.50.

Bruce Sherwood

Re: [Visualpython-users] redblue stereo

[P H B. <P.H...@bh...>]

> 
> I've just ordered some glasses from 
> http://www.tedpella.com/photo_html/stereo.htm. A box of 10 red-blue 
> glasses is $4.50.
> 
> Bruce Sherwood
> 

Some years ago I bought inexpensive red/blue glasses from Karran Products,
Lightwater, Surrey, England. 

see http://www.karran.co.uk/Frames/b3d.html#anchor273342 

-- 
Dr P H Borcherds	|<mailto:P.H...@bh...>
			|phone 	0044 (0)121 475 3029