P3D RE: Cheap entre' into 3-D video viewing

[Marcus Warrington <marcusw@xxxxxxxxx>]

On Friday 14 Aug 1998 Dana wrote ;

>Could anyone recommend an inexpensive system for 3-D video viewing?
>I'd like to move beyond the crappy anaglyph videos I have. How does it 
>work?

buy some VRex glasses (Classic Pack)  in the many closing out sales on
Ebay I've seen numerous packs going for round $30 !
I have a set myself that I bought from VRex directly (costing $90) and although
they have their failings (mainly the fact that they are uncomfortable to wear) they
are cheap and , to my mind, benefit from the wireless IR transmission..

The way it works is that a television picture is made of 50 frames a second PAL
or 60 frames a second NTSC, each frame is made up of two fields. One field
holds all the even scan lines and the other holds all the odd lines. When a frame
is displayed on the TV all even lines are displayed (field 1) then all odd lines are
displayed (field2). This means that each field refreshes 25 times a second (PAL)
and whole display refreshes 50 times a second. This process is called interlacing.
Field Sequential video utilises this dual refreshing by encoding one view (left) into
one field and the other view (right) in the other field. The LCS glasses then synch to
the vertical blank signal (the point between each field being displayed) and block the
view of the opposite eye. i.e. as field 1 (even lines) is displayed the glasses block
the view of the right eye (assuming even lines have the left view encoded in them),
then when field 2 is displayed the glasses flip and block the left eye. This technique
relies on the fact that the phosphor (that creates the image on the TV) only emits
light for a short time and then starts to decay, so once the second field is displayed 
the first field as decayed to such an extend that its hardly visible.

Unfortunately , although this provides compatibility with existing TV signals
and hardware it does half the effective refresh rate to 25th of a second per eye (PAL)
Obviously NTSC has the advantage here since its refresh rate is higher to start with,
on the other hand PAL has greater vertical resolution and its colour rendition is better.

>Are the results at all impressive?

I thought they were... although anything in 3D is impressive. :)
In all honesty I'd say for $30 they are well worth the investment, even for $90
I'm happy. They main problem is flicker... but if you think its bad spare a thought
for us PAL users :)

The VRex glasses come with a demo video so they seem to be the best way of
sampling field sequential video cheaply...

> How many polarized films have been converted to video? 

Don't know , but I'd also like know , and know of somewhere that sells them. 
Searching the Net for 3D movies brings up a few adult titles but I haven't found
anywhere selling anything else.... yet..

>Do many people here use those video splitters for regular camcorders? If 
>you do, how pleased are you pleased with the results?

Funny you should ask that.... I just got mine (from Dalia)
(I'm assuming your referring to the NuView adapter)
They quality is fine, and the effect is definitely 3D.  I've not had time to
really try it out yet (only had it 3 days) but I found it impressive and am looking
forward to learning to use it effectively. 

The only advice I'd give is to check out your camcorder first, the Sony range 
seem ideal because the unit is designed for a 37mm thread, and Sony's new 
XR range give greater horizontal resolution (just what we need in stereo), I also 
went for Hi8 for the same reason. The camera *NEEDS* to have a tripod mount
and a Video Out connector (for the adapter to synch to). This seems to pretty
much rule out the current range of dinky digital camcorders, but it MAY also 
impact on lo-band VHS-C camcorders since I'm unsure if all these have a Video 
Out connector (since the tape can be played back on a normal VHS VCR).

When I posted asking for views on the NuView the *ONLY* response I got was
from Harold Baize (who convinced me to buy one .. thanks Harold:)). In the last
week I've seen two more post asking about it.. so it looks like interest is  beginning to
grow. Time to start a new list folks.. VID-3D anyone ;^)

Marcus ?8^p
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