Film-Tech Cinema Systems
Film-Tech Forum ARCHIVE


  
my profile | my password | search | faq & rules | forum home
  next oldest topic   next newest topic
» Film-Tech Forum ARCHIVE   » Operations   » Digital Cinema Forum   » Definition of "dual digital"? (Page 1)

 
This topic comprises 2 pages: 1  2 
 
Author Topic: Definition of "dual digital"?
Mike Croaro
Master Film Handler

Posts: 394
From: Millbrae, CA
Registered: Apr 2005


 - posted 05-31-2009 12:02 AM      Profile for Mike Croaro   Email Mike Croaro   Send New Private Message       Edit/Delete Post 
Re: Up in 3D

What is the difference between "dual digital" and regular digital.

See the attached link to the Grand Lake Theatre is Oakland, CA which boasts on their webiste that they are the only theatre in Northern California with "dual digital".

http://renaissancerialto.com/

Mike

 |  IP: Logged

Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003


 - posted 05-31-2009 12:48 AM      Profile for Sam D. Chavez   Author's Homepage     Send New Private Message       Edit/Delete Post 
This was discussed in the thread below, cheap 3D.

I did this project and we used two Christie ZX projectors with passive Master Image Polarizing filters in front of each lens.

One projector is left eye, the other is right eye.

The glasses are the same as other Master Image systems.

There are a number of advantages, there is plenty of light and if 3D goes away, you have a second projector to use for D-Cinema in future.

 |  IP: Logged

Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 05-31-2009 01:10 AM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
They mean they are using two projectors instead of one. Imax, i.e., does it this way (with dual-projectors).

This could hold the following (practical) advantages over SOME single projector systems, specially when playing 3D titles:

-Potentially brighter picture, by using two projection lamps instead of one. This could also allow for a potentially larger screen as well, i.e.

-No "3D flicker" (no temporal disparities). This is a slight defect that occurs on single projectors when one eye is seeing one thing that is different in time from what the other eye "remembers". In short: it gives some people some eye fatigue/headaches/weird feelings sometimes. Dual projectors or Sony 3D single projector do NOT need to have this effect.

-Potentially higher quality picture, with double the color resolution (4:4:4 instead of 4:2:2) and larger color gamut (12 bits against 10 bits). Sony 3D single projection system also has this advantage.

-Potentially, a dual projection system could be made to have less ghosting (3D double-images) than some single projection systems. But some single projection systems, like Dolby, can be as good or even better in this department.

-For 2D applications, the screendoor "artifact" could be less visible. Sitting close to the screen, it may be apparent the black space between the pixels, called the "screendoor", on many projectors. By using two projectors together, their screen-door effect could be less apparent by "blurring" together.

But dual-projection can have its dissadvantages. I.e. if both projectors are not calibrated/adjusted perfectly, the images in 3D may appear assymetrical. They need to match in color, brightness (i.e. lamp aligment and output), etc. It's not possible to align the images 100.00% identically, so there is always some (very) minor keystone disparities between the images, etc.

Also, specially if placed side-by-side instead of one on top of the other, they could show assymetries in silver screens 'cos of the hotspots being (slightly) different for each image.

And, of course, it can cost twice as much as a single projection to buy and run (i.e. two lamps/double the electricity).

 |  IP: Logged

Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 05-31-2009 02:11 AM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
When using dual projectors, wouldn't any standard passive polarizaton filters work just fine? Why would you need to use Master Image polarizing filters and glasses, i.e., couldn't you use any circular polarization filters and glasses (or even the older horizontal/vertical polarization)?

PS -- can someone explain the meaning of 4:4:4 and 4:2:2 -- thanks.

 |  IP: Logged

Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 05-31-2009 09:52 AM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
Master Image also offers passive polarization filters:

http://masterimage.co.kr/new_eng/product/system_02.htm?pos=22

You could, indeed, use linear polarization instead of circular like it has been the preferred method in the past (i.e., Imax Prime [Razz] ). It would have a slight advantage in brightness, ghosting and cost over circular. With the drawback that is more sensitive to geometrical angle-dependant performance (i.e. patrons need to keep their heads perfectly leveled or ghosting starts to appear, worse for larger screens or steep projection angles, etc).

4:4:4 and 4:2:2 are terms used in the video industry to refer, in short, to how the video signal is sampled. The video signal usually travels in 3 components, like 3 signals, which could represent each primary color (i.e. Red Green Blue) or a multi component signal (i.e. luminance+2 channels of chrominance).

What it means, in short, is having X number of pixels in one channel, typically the luminance channel (Y or the "black and white image") and a relative number of pixels on the other two channels (i.e. the "color difference channels"). So for 4:2:2 it could mean, i.e., that for each 4 pixels on each scanning line in the first channel, there are 2 pixels in each one of the other 2 channels horizontally and another 2 in the next scanning line.

There are many variations of this and sometimes the notation is not all that ... there. But it's a way to talk about "stuff" in the image, like color, having more or less resolution than other "stuff" in the same image, like some other color channel or luminance, and how the (sub) samples are located in the image vertically and horizontally compared to the main (not sub-sampled) channel.

Here it's better explained:

http://en.wikipedia.org/wiki/Chroma_subsampling

 |  IP: Logged

Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 05-31-2009 08:45 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
Looks like SONY is on the 4:4:4: program well enough with their 4k units.

This might be the way to go for both 2d and 3d projection ...

For I'm one of them that can call tell that 4:2:2: 3d isn't really for me for I do experience slight effects (like mild eye strain for beginners) of the triple flash, alternating eye presentations...

 |  IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 05-31-2009 09:52 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Monte,

Dual projector 3-D is stuck at 4:2:2 for now because only one HDSI output on the server feeds each projector... limiting each proj. to 10 data bits. That of course could change and is a clear advantage to having two projector 3-D instead of just one.

Mark

 |  IP: Logged

Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 05-31-2009 09:58 PM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
Mark forgot to mention that the Qube server comes standard with dual-dual SDI connection (and thus, capable of 4:4:4 12bits 3D for dual-projectors) and that it's an option on other servers as well, such as GDC's, for example.

The Qube is capable of decoding two separates full quality 2K packages simultaneously and comes standard with quad-sdi, so I see no reason why they wouldn't decode a 3D 48fps at full quality feeding each dual-sdi output, unless Qube engineers were really lazy that day ...

 |  IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 06-01-2009 08:54 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
I didn't mention it because I'm not sure the dual outputs will fuinction in 3-D mode or not. They very definately will in 2-D.

Mark

 |  IP: Logged

Jack Theakston
Master Film Handler

Posts: 411
From: New York, USA
Registered: Sep 2007


 - posted 06-02-2009 01:40 PM      Profile for Jack Theakston   Email Jack Theakston   Send New Private Message       Edit/Delete Post 
quote:
-No "3D flicker" (no temporal disparities). This is a slight defect that occurs on single projectors when one eye is seeing one thing that is different in time from what the other eye "remembers". In short: it gives some people some eye fatigue/headaches/weird feelings sometimes. Dual projectors or Sony 3D single projector do NOT need to have this effect.
AKA "Out of phase".

quote: Frank Angel
When using dual projectors, wouldn't any standard passive polarizaton filters work just fine?
Yes, but you're paying for it, and the current circular polarizers have the advantage of no cross-talk when you move your head.

 |  IP: Logged

System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004


 - posted 02-27-2013 10:52 AM      Profile for System Notices         Edit/Delete Post 

It has been 1365 days since the last post.


 |  IP: Logged

Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 02-27-2013 10:52 AM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
Just curious:

Is dual-projector a "3D-Only" format, or are these setups ever installed/used for 2D?

If so, how is it possible to get the 2 images to perfectly overlay? I would expect two projectors -- even mounted over/under -- to have slightly different keystoning. No?

Also, what is the source of the signal to the 2nd projector?

 |  IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 02-27-2013 11:08 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Check out Christie's "Duo" system. It will indeed handle dual projector 2D...even on curved screens.

Christie Duo

 |  IP: Logged

Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 02-27-2013 12:10 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
quote: Manny Knowles
Is dual-projector a "3D-Only" format, or are these setups ever installed/used for 2D?
IMAX Digital runs both projectors on 2D shows. The intention is to hide the screen door effect and pixel grid. Both projectors seem to do that, but the end result is a somewhat soft looking image on a pretty big screen. IMAX Digital really needs to move up to at least a dual 4K projector solution. If they're working with 4K the imagery should be at least adequately sharp (provided the movie being shown was originated in 4K).

 |  IP: Logged

Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 02-27-2013 12:41 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
Next question: Do all dual systems use a beam splitter?

 |  IP: Logged



All times are Central (GMT -6:00)
This topic comprises 2 pages: 1  2 
 
   Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:



Powered by Infopop Corporation
UBB.classicTM 6.3.1.2

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.

© 1999-2020 Film-Tech Cinema Systems, LLC. All rights reserved.